diff --git a/CHANGELOG.md b/CHANGELOG.md
index 561fe41c2..2d5a9a91e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,8 @@ Released ...
 
 Summary: TODO
 
+- Added `color-to-alpha` `image-filter` to allow for applying alpha in proportion to color similiarity (#2023)
+
 - Added Async support to PostGIS plugin - https://github.com/mapnik/mapnik/wiki/PostGIS-Async
 
 - Fixed alpha handling bug with `comp-op:dst-over` (#1995)
@@ -307,9 +309,9 @@ Released Aug 23, 2012
 
 - Improved logging/debugging system with release logs and file redirection (https://github.com/mapnik/mapnik/wiki/Runtime-Logging) (#937 and partially #986, #467)
 
-- GDAL: allow setting nodata value on the fly (will override value if nodata is set in data) (#1161)
+- GDAL: allow setting `nodata` value on the fly (will override value if `nodata` is set in data) (#1161)
 
-- GDAL: respect nodata for paletted/colormapped images (#1160)
+- GDAL: respect `nodata` for paletted/colormapped images (#1160)
 
 - PostGIS: Added a new option called `autodetect_key_field` (by default false) that if true will
   trigger autodetection of the table primary key allowing for feature.id() to represent
@@ -446,7 +448,7 @@ Released September 26, 2011
   cannot possibly be projected into the map srs or the user wishes to control map bounds without
   modifying the extents of each layer.
 
-- Support for NODATA values with grey and rgb images in GDAL plugin (#727)
+- Support for `nodata` values with grey and rgb images in GDAL plugin (#727)
 
 - Print warning if invalid XML property names are used (#110)
 
diff --git a/include/mapnik/image_filter.hpp b/include/mapnik/image_filter.hpp
index 4d41ea4a6..b871f8c10 100644
--- a/include/mapnik/image_filter.hpp
+++ b/include/mapnik/image_filter.hpp
@@ -406,6 +406,77 @@ void apply_filter(Src & src, agg_stack_blur const& op)
     agg::stack_blur_rgba32(pixf,op.rx,op.ry);
 }
 
+inline double channel_delta(double source, double match)
+{
+    if (source > match) return (source - match) / (1.0 - match);
+    if (source < match) return (match - source) / match;
+    return (source - match);
+}
+
+inline uint8_t apply_alpha_shift(double source, double match, double alpha)
+{
+    source = (((source - match) / alpha) + match) * alpha;
+    return static_cast<uint8_t>(std::floor((source*255.0)+.5));
+}
+
+template <typename Src>
+void apply_filter(Src & src, color_to_alpha const& op)
+{
+    using namespace boost::gil;
+    rgba8_view_t src_view = rgba8_view(src);
+    double cr = static_cast<double>(op.color.red())/255.0;
+    double cg = static_cast<double>(op.color.green())/255.0;
+    double cb = static_cast<double>(op.color.blue())/255.0;
+    for (int y=0; y<src_view.height(); ++y)
+    {
+        rgba8_view_t::x_iterator src_it = src_view.row_begin(y);
+        for (int x=0; x<src_view.width(); ++x)
+        {
+            uint8_t & r = get_color(src_it[x], red_t());
+            uint8_t & g = get_color(src_it[x], green_t());
+            uint8_t & b = get_color(src_it[x], blue_t());
+            uint8_t & a = get_color(src_it[x], alpha_t());
+            double sr = static_cast<double>(r)/255.0;
+            double sg = static_cast<double>(g)/255.0;
+            double sb = static_cast<double>(b)/255.0;
+            double sa = static_cast<double>(a)/255.0;
+            // demultiply
+            if (sa <= 0.0)
+            {
+                r = g = b = 0;
+                continue;
+            }
+            else
+            {
+                sr /= sa;
+                sg /= sa;
+                sb /= sa;
+            }
+            // get that maximum color difference
+            double xa = std::max(channel_delta(sr,cr),std::max(channel_delta(sg,cg),channel_delta(sb,cb)));
+            if (xa > 0)
+            {
+                // apply difference to each channel, returning premultiplied
+                // TODO - experiment with difference in hsl color space
+                r = apply_alpha_shift(sr,cr,xa);
+                g = apply_alpha_shift(sg,cg,xa);
+                b = apply_alpha_shift(sb,cb,xa);
+                // combine new alpha with original
+                xa *= sa;
+                a = static_cast<uint8_t>(std::floor((xa*255.0)+.5));
+                // all color values must be <= alpha
+                if (r>a) r=a;
+                if (g>a) g=a;
+                if (b>a) b=a;
+            }
+            else
+            {
+                r = g = b = a = 0;
+            }
+        }
+    }
+}
+
 template <typename Src>
 void apply_filter(Src & src, colorize_alpha const& op)
 {
diff --git a/include/mapnik/image_filter_grammar.hpp b/include/mapnik/image_filter_grammar.hpp
index 26156fbf1..18aa765f4 100644
--- a/include/mapnik/image_filter_grammar.hpp
+++ b/include/mapnik/image_filter_grammar.hpp
@@ -75,6 +75,7 @@ struct image_filter_grammar :
     css_color_grammar<Iterator> css_color_;
     qi::rule<Iterator,void(mapnik::filter::color_stop &),qi::ascii::space_type> color_stop_offset;
     phoenix::function<percent_offset_impl> percent_offset;
+    qi::rule<Iterator, qi::locals<color>, void(ContType&), qi::ascii::space_type> color_to_alpha_filter;
 };
 
 }
diff --git a/include/mapnik/image_filter_types.hpp b/include/mapnik/image_filter_types.hpp
index c3f0d54e9..9ff5ab516 100644
--- a/include/mapnik/image_filter_types.hpp
+++ b/include/mapnik/image_filter_types.hpp
@@ -59,6 +59,13 @@ struct agg_stack_blur
     unsigned ry;
 };
 
+struct color_to_alpha
+{
+    color_to_alpha(mapnik::color const& c)
+        : color(c) {}
+    mapnik::color color;
+};
+
 struct scale_hsla
 {
     scale_hsla(double _h0, double _h1,
@@ -132,7 +139,8 @@ typedef boost::variant<filter::blur,
                        filter::y_gradient,
                        filter::invert,
                        filter::scale_hsla,
-                       filter::colorize_alpha> filter_type;
+                       filter::colorize_alpha,
+                       filter::color_to_alpha> filter_type;
 
 inline std::ostream& operator<< (std::ostream& os, blur)
 {
@@ -152,6 +160,12 @@ inline std::ostream& operator<< (std::ostream& os, agg_stack_blur const& filter)
     return os;
 }
 
+inline std::ostream& operator<< (std::ostream& os, color_to_alpha const& filter)
+{
+    os << "color-to-alpha(" << filter.color << ')';
+    return os;
+}
+
 inline std::ostream& operator<< (std::ostream& os, scale_hsla const& filter)
 {
     os << "hsla-transform(" << filter.h0 << 'x' << filter.h1 << ':'
diff --git a/src/image_filter_grammar.cpp b/src/image_filter_grammar.cpp
index a17191d14..033dc96d6 100644
--- a/src/image_filter_grammar.cpp
+++ b/src/image_filter_grammar.cpp
@@ -91,6 +91,8 @@ image_filter_grammar<Iterator,ContType>::image_filter_grammar()
         scale_hsla_filter(_val)
         |
         colorize_alpha_filter(_val)
+        |
+        color_to_alpha_filter(_val)
         ;
 
     agg_blur_filter = lit("agg-stack-blur")[_a = 1, _b = 1]
@@ -122,6 +124,14 @@ image_filter_grammar<Iterator,ContType>::image_filter_grammar()
         |
         double_[at_c<1>(_r1) = _1]
         ;
+
+    color_to_alpha_filter = lit("color-to-alpha")
+        >> lit('(')
+        >> css_color_[_a = _1]
+        >> lit(')')
+        [push_back(_r1,construct<mapnik::filter::color_to_alpha>(_a))]
+        ;
+
     no_args = -(lit('(') >> lit(')'));
 }
 
diff --git a/tests/visual_tests/grids/raster-color-to-alpha1-512-512-1.0-grid-reference.json b/tests/visual_tests/grids/raster-color-to-alpha1-512-512-1.0-grid-reference.json
new file mode 100644
index 000000000..53162f357
--- /dev/null
+++ b/tests/visual_tests/grids/raster-color-to-alpha1-512-512-1.0-grid-reference.json
@@ -0,0 +1,136 @@
+{
+ "keys": [
+  ""
+ ], 
+ "data": {}, 
+ "grid": [
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                "
+ ]
+}
\ No newline at end of file
diff --git a/tests/visual_tests/grids/raster-color-to-alpha2-512-512-1.0-grid-reference.json b/tests/visual_tests/grids/raster-color-to-alpha2-512-512-1.0-grid-reference.json
new file mode 100644
index 000000000..53162f357
--- /dev/null
+++ b/tests/visual_tests/grids/raster-color-to-alpha2-512-512-1.0-grid-reference.json
@@ -0,0 +1,136 @@
+{
+ "keys": [
+  ""
+ ], 
+ "data": {}, 
+ "grid": [
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
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+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                "
+ ]
+}
\ No newline at end of file
diff --git a/tests/visual_tests/grids/raster-color-to-alpha3-512-512-1.0-grid-reference.json b/tests/visual_tests/grids/raster-color-to-alpha3-512-512-1.0-grid-reference.json
new file mode 100644
index 000000000..53162f357
--- /dev/null
+++ b/tests/visual_tests/grids/raster-color-to-alpha3-512-512-1.0-grid-reference.json
@@ -0,0 +1,136 @@
+{
+ "keys": [
+  ""
+ ], 
+ "data": {}, 
+ "grid": [
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                "
+ ]
+}
\ No newline at end of file
diff --git a/tests/visual_tests/grids/raster-color-to-alpha4-512-512-1.0-grid-reference.json b/tests/visual_tests/grids/raster-color-to-alpha4-512-512-1.0-grid-reference.json
new file mode 100644
index 000000000..53162f357
--- /dev/null
+++ b/tests/visual_tests/grids/raster-color-to-alpha4-512-512-1.0-grid-reference.json
@@ -0,0 +1,136 @@
+{
+ "keys": [
+  ""
+ ], 
+ "data": {}, 
+ "grid": [
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                "
+ ]
+}
\ No newline at end of file
diff --git a/tests/visual_tests/grids/raster-color-to-alpha5-512-512-1.0-grid-reference.json b/tests/visual_tests/grids/raster-color-to-alpha5-512-512-1.0-grid-reference.json
new file mode 100644
index 000000000..53162f357
--- /dev/null
+++ b/tests/visual_tests/grids/raster-color-to-alpha5-512-512-1.0-grid-reference.json
@@ -0,0 +1,136 @@
+{
+ "keys": [
+  ""
+ ], 
+ "data": {}, 
+ "grid": [
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                ", 
+  "                                                                                                                                "
+ ]
+}
\ No newline at end of file
diff --git a/tests/visual_tests/images/raster-color-to-alpha1-512-512-1.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha1-512-512-1.0-agg-reference.png
new file mode 100644
index 000000000..1a0e0ac35
Binary files /dev/null and b/tests/visual_tests/images/raster-color-to-alpha1-512-512-1.0-agg-reference.png differ
diff --git a/tests/visual_tests/images/raster-color-to-alpha1-512-512-2.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha1-512-512-2.0-agg-reference.png
new file mode 100644
index 000000000..1a0e0ac35
Binary files /dev/null and b/tests/visual_tests/images/raster-color-to-alpha1-512-512-2.0-agg-reference.png differ
diff --git a/tests/visual_tests/images/raster-color-to-alpha2-512-512-1.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha2-512-512-1.0-agg-reference.png
new file mode 100644
index 000000000..c14a73108
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diff --git a/tests/visual_tests/images/raster-color-to-alpha2-512-512-2.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha2-512-512-2.0-agg-reference.png
new file mode 100644
index 000000000..c14a73108
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diff --git a/tests/visual_tests/images/raster-color-to-alpha3-512-512-1.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha3-512-512-1.0-agg-reference.png
new file mode 100644
index 000000000..c750b1f83
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new file mode 100644
index 000000000..c750b1f83
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diff --git a/tests/visual_tests/images/raster-color-to-alpha4-512-512-1.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha4-512-512-1.0-agg-reference.png
new file mode 100644
index 000000000..1ec158dbc
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diff --git a/tests/visual_tests/images/raster-color-to-alpha4-512-512-2.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha4-512-512-2.0-agg-reference.png
new file mode 100644
index 000000000..1ec158dbc
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diff --git a/tests/visual_tests/images/raster-color-to-alpha5-512-512-1.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha5-512-512-1.0-agg-reference.png
new file mode 100644
index 000000000..b75988967
Binary files /dev/null and b/tests/visual_tests/images/raster-color-to-alpha5-512-512-1.0-agg-reference.png differ
diff --git a/tests/visual_tests/images/raster-color-to-alpha5-512-512-2.0-agg-reference.png b/tests/visual_tests/images/raster-color-to-alpha5-512-512-2.0-agg-reference.png
new file mode 100644
index 000000000..b75988967
Binary files /dev/null and b/tests/visual_tests/images/raster-color-to-alpha5-512-512-2.0-agg-reference.png differ
diff --git a/tests/visual_tests/styles/raster-color-to-alpha1.xml b/tests/visual_tests/styles/raster-color-to-alpha1.xml
new file mode 100644
index 000000000..5a66751ef
--- /dev/null
+++ b/tests/visual_tests/styles/raster-color-to-alpha1.xml
@@ -0,0 +1,19 @@
+<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over"
+>
+
+<Style name="style" image-filters="color-to-alpha(#00BDFF)">
+  <Rule>
+    <RasterSymbolizer opacity="1"/>
+  </Rule>
+</Style>
+<Layer name="raster"
+  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
+    <StyleName>style</StyleName>
+    <Datasource>
+       <!-- https://github.com/mapnik/mapnik/issues/1471 -->
+       <Parameter name="file">../../data/raster/nodata-edge.tif</Parameter>
+       <Parameter name="type">gdal</Parameter>
+    </Datasource>
+  </Layer>
+
+</Map>
\ No newline at end of file
diff --git a/tests/visual_tests/styles/raster-color-to-alpha2.xml b/tests/visual_tests/styles/raster-color-to-alpha2.xml
new file mode 100644
index 000000000..cd0206ef4
--- /dev/null
+++ b/tests/visual_tests/styles/raster-color-to-alpha2.xml
@@ -0,0 +1,20 @@
+<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over"
+ background-color="steelblue"
+>
+
+<Style name="style" image-filters="color-to-alpha(#BCDAF5)">
+  <Rule>
+    <RasterSymbolizer opacity="1" scaling="quadric"/>
+  </Rule>
+</Style>
+<Layer name="raster"
+  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
+    <StyleName>style</StyleName>
+    <Datasource>
+       <!-- https://github.com/mapnik/mapnik/issues/1471 -->
+       <Parameter name="file">../../data/raster/river_merc.tiff</Parameter>
+       <Parameter name="type">gdal</Parameter>
+    </Datasource>
+  </Layer>
+
+</Map>
\ No newline at end of file
diff --git a/tests/visual_tests/styles/raster-color-to-alpha3.xml b/tests/visual_tests/styles/raster-color-to-alpha3.xml
new file mode 100644
index 000000000..393e50669
--- /dev/null
+++ b/tests/visual_tests/styles/raster-color-to-alpha3.xml
@@ -0,0 +1,20 @@
+<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over"
+ background-color="steelblue"
+>
+
+<Style name="style" image-filters="color-to-alpha(black)">
+  <Rule>
+    <RasterSymbolizer opacity="1" scaling="quadric"/>
+  </Rule>
+</Style>
+<Layer name="raster"
+  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
+    <StyleName>style</StyleName>
+    <Datasource>
+       <!-- https://github.com/mapnik/mapnik/issues/1471 -->
+       <Parameter name="file">../../data/raster/transp.tiff</Parameter>
+       <Parameter name="type">gdal</Parameter>
+    </Datasource>
+  </Layer>
+
+</Map>
\ No newline at end of file
diff --git a/tests/visual_tests/styles/raster-color-to-alpha4.xml b/tests/visual_tests/styles/raster-color-to-alpha4.xml
new file mode 100644
index 000000000..40fbdc08a
--- /dev/null
+++ b/tests/visual_tests/styles/raster-color-to-alpha4.xml
@@ -0,0 +1,27 @@
+<Map background-color="white" srs="+init=epsg:32630" minimum-version="0.7.2">
+
+  <Style name="DISCRETE RAINBOW" direct-image-filters="color-to-alpha(white)" image-filters="color-to-alpha(yellow),color-to-alpha(blue)">
+    <Rule>
+      <RasterSymbolizer>
+        <RasterColorizer default-mode="discrete" default-color="white">
+            <stop color="red" value="0"/>
+            <stop color="orange" value="5"/>
+            <stop color="yellow" value="10"/>
+            <stop color="green" value="15"/>
+            <stop color="blue" value="20"/>
+            <stop color="indigo" value="25"/>
+        </RasterColorizer>
+      </RasterSymbolizer>
+    </Rule>
+  </Style>
+
+  <Layer name="dataraster" srs="+init=epsg:32630">
+      <StyleName>DISCRETE RAINBOW</StyleName>
+      <Datasource>
+          <Parameter name="file">../../data/raster/dataraster.tif</Parameter>
+          <Parameter name="type">gdal</Parameter>
+          <Parameter name="band">1</Parameter>
+      </Datasource>
+  </Layer>
+
+</Map>
\ No newline at end of file
diff --git a/tests/visual_tests/styles/raster-color-to-alpha5.xml b/tests/visual_tests/styles/raster-color-to-alpha5.xml
new file mode 100644
index 000000000..6a2f4add6
--- /dev/null
+++ b/tests/visual_tests/styles/raster-color-to-alpha5.xml
@@ -0,0 +1,27 @@
+<Map background-color="white" srs="+init=epsg:32630" minimum-version="0.7.2">
+
+  <Style name="DISCRETE RAINBOW" image-filters="color-to-alpha(black)">
+    <Rule>
+      <RasterSymbolizer>
+        <RasterColorizer default-mode="discrete" default-color="white">
+            <stop color="red" value="0"/>
+            <stop color="orange" value="5"/>
+            <stop color="yellow" value="10"/>
+            <stop color="green" value="15"/>
+            <stop color="blue" value="20"/>
+            <stop color="indigo" value="25"/>
+        </RasterColorizer>
+      </RasterSymbolizer>
+    </Rule>
+  </Style>
+
+  <Layer name="dataraster" srs="+init=epsg:32630">
+      <StyleName>DISCRETE RAINBOW</StyleName>
+      <Datasource>
+          <Parameter name="file">../../data/raster/dataraster.tif</Parameter>
+          <Parameter name="type">gdal</Parameter>
+          <Parameter name="band">1</Parameter>
+      </Datasource>
+  </Layer>
+
+</Map>
\ No newline at end of file
diff --git a/tests/visual_tests/test.py b/tests/visual_tests/test.py
index 7140900d0..3346826fe 100755
--- a/tests/visual_tests/test.py
+++ b/tests/visual_tests/test.py
@@ -179,6 +179,11 @@ files = {
     'vrt_colortable':{'sizes':[(256,256)]},
     'raster_colorizer':{'sizes':[(512,512)]},
     'raster_symbolizer':{'sizes':[(512,512)]},
+    'raster-color-to-alpha1':{'sizes':[(512,512)]},
+    'raster-color-to-alpha2':{'sizes':[(512,512)]},
+    'raster-color-to-alpha3':{'sizes':[(512,512)]},
+    'raster-color-to-alpha4':{'sizes':[(512,512)]},
+    'raster-color-to-alpha5':{'sizes':[(512,512)]}
     }
 
 class Reporting: