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Updated Image IO (markdown)

Dane Springmeyer 2016-02-25 15:34:48 -08:00
parent 146ee74e72
commit 4b8f8391e3
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Image-IO.md

@ -83,7 +83,7 @@ And the key:value options can be controlled as follows:
| m | string, `o` or `h` | `h` | Applies to paletted png only. This is the quantization method: `o` stands for `octree` and `h` stands for `hextree`. The `octree` quantizer only supports limited alpha ranges and so for images with detailed alpha this may produce a poorer quality image. However the `octree` encoder is faster than the `hextree` encoder. The `hextree` encoder is default (as of >= Mapnik 2.3.x) because it produces the highest quality output - nearly visually identical to full color png. If your maps do no contain any alpha (e.g. they have a completely opaque background) then full color png or `png8:m=o` may produce smaller pngs at a faster rate, however we plan to optimize this pathway automatically [in the future](https://github.com/mapnik/mapnik/issues/2029). | | m | string, `o` or `h` | `h` | Applies to paletted png only. This is the quantization method: `o` stands for `octree` and `h` stands for `hextree`. The `octree` quantizer only supports limited alpha ranges and so for images with detailed alpha this may produce a poorer quality image. However the `octree` encoder is faster than the `hextree` encoder. The `hextree` encoder is default (as of >= Mapnik 2.3.x) because it produces the highest quality output - nearly visually identical to full color png. If your maps do no contain any alpha (e.g. they have a completely opaque background) then full color png or `png8:m=o` may produce smaller pngs at a faster rate, however we plan to optimize this pathway automatically [in the future](https://github.com/mapnik/mapnik/issues/2029). |
| g | float, 1.0 - 2.0 | 2.0 | Not likely that you need to change this option. It is the gamma correction for pixel arithmetic in hextree method. 1.0 means no gamma correction | | g | float, 1.0 - 2.0 | 2.0 | Not likely that you need to change this option. It is the gamma correction for pixel arithmetic in hextree method. 1.0 means no gamma correction |
| s | string, `default`, `filtered`, `huff`, or `rle` | `default` | Not likely that you need to change this option. It is the ZLIB compression strategy. See zlib docs for more details (available in Mapnik >= 2.x) | | s | string, `default`, `filtered`, `huff`, or `rle` | `default` | Not likely that you need to change this option. It is the ZLIB compression strategy. See zlib docs for more details (available in Mapnik >= 2.x) |
| e | string, `miniz` or `libpng` | 'libpng` | REMOVED in Mapnik 3.0.10 ~~Experimental: not recommended to set this option. `e=miniz` triggers using the experimental miniz encoder support instead of `libpng`. In some cases this encoder provides better encoding speeds with minor size differences but it also does not work fully yet (bugs we need to track down)~~ | | e | string, `miniz` or `libpng` | 'libpng` | REMOVED in Mapnik 3.0.10 |
### WEBP output options ### WEBP output options