[mapserver-users] CLASS directive

[Mark Korver]

Maybe you can just define the layer 2X in the mapfile.  Put the
altered layer on top of the regular layer? I am assuming that you can
get the good values to be transparent and not white.

On Tue, Apr 26, 2011 at 11:57 AM, Matt Bartolome <mattxbart at gmail.com> wrote:
> Hello,
> I have a funky raster I'm trying to tile as jpegs. For whatever reason this
> RGB raster has white pixels on the source raster which should be black. Is
> it possible to set only these white pixels to be black on the output jpeg? I
> was playing around with the CLASS directive. This sets all those white
> pixels to black, but it does not preserve the rest of the rgb that I want to
> use; those "good" values are not processed and show as blank (white) space.
> How do I do this? I thought of preprocessing this with gdalwarp but the
> raster becomes too large (source is an ecw) on output so need to do it
> on-the-fly with mapserver (I'm using mapserver trunk and gdal 1.8 on linux).
>
> Thanks!
> Matt
>
> OUTPUTFORMAT
>     NAME jpeg
>     DRIVER "AGG/JPEG"
>     MIMETYPE "image/jpeg"
>     IMAGEMODE RGB
>     EXTENSION "jpg"
> END
>
> LAYER
>   NAME "test"
>   TYPE RASTER
>   STATUS ON
>   DATA "/test.tif"
>
>   PROJECTION
>     "init=epsg:2230"
>   END
>
>   PROCESSING "NODATA=255"
>
>   CLASS
>     NAME "set white to black"
>     EXPRESSION ([red] = 255 AND [green] = 255 AND [blue] = 255)
>     STYLE
>     COLOR 0 0 0
>   END
>
> END
>
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