MS RFC 21: MapServer Raster Color Correction

[Frank Warmerdam]

Stephen Woodbridge wrote:
> Frank Warmerdam wrote:
>> Folks,
>>
>> A new RFC for a raster related feature:
>>
>>   http://mapserver.gis.umn.edu/development/rfc/ms-rfc-21/
>>
>> Consider, comment, vote...
>>
> 
> +1 looks like a very nice feature.

Steve,

Thanks

> I don't suppose this would help with stabilizing image colors in the 
> ka-map tile generation when one uses:
> 
>   OUTPUTFORMAT
>     NAME PNG8
>     DRIVER "GD/PNG"
>     EXTENSION "png"
>     MIMETYPE "image/png"
>     IMAGEMODE RGBA
>     TRANSPARENT OFF
>     FORMATOPTION "QUANTIZE_FORCE=ON"
>     FORMATOPTION "QUANTIZE_DITHER=OFF"
>     FORMATOPTION "QUANTIZE_COLORS=256"
>   END
> 
> as the output format. There is a subtle shift in the color palette from 
> meta tile to metatile during the QUANTIZE step.
> 
> Not asking for a change in scope of the rfc, just wondering.

No, it won't help. What you really need for that is a way of referring
to a fixed quantization colormap.  The problem is that each map request
results in an "optimized" colormap for that request.  Generally that is
good, but in a tiled situation it results in slight variations between
requests that are undesirable.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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