[mapserver-users] AGG renderer and paletted RGBA PNG's

[Roger André]

Hi All,

I'm seeing a problem in some of my raster data which have graduated color
ramps in them.  When using the AGG renderer, the data appears to have
discreet colors (which is incorrect), whereas with the GD renderer, we get
correct color gradients.

The GD outputformat looks like this:

  OUTPUTFORMAT
   NAME 'png'
   DRIVER GD/PNG
   IMAGEMODE RGBA
   EXTENSION "png"
   FORMATOPTION "TRANSPARENT=ON"
   FORMATOPTION "INTERLACE=OFF"
   TRANSPARENT ON
  END #end outputformat


The AGG outputformat looks like this:

OUTPUTFORMAT
  NAME 'AGGA'
  DRIVER AGG/PNG
  IMAGEMODE RGBA
  EXTENSION "png"
  MIMETYPE "image/png; mode=24bit"
  FORMATOPTION "TRANSPARENT=ON"
  FORMATOPTION "INTERLACE=OFF"
END

In addition, the output image appears to have a color palette, instead of
being a  4-ch png.  Finally, the problem is present in WMS requests, but not
straight MODE=map requests.

My WMS request looks like this:
http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/hydro/hydro.map&SERVICE=WMS&version=%221.1.1%22&REQUEST=GetMap&LAYERS=imagery&STYLES=&BBOX=-125,39,-108,54&WIDTH=600&HEIGHT=600&FORMAT=png&SRS=epsg:4326

Any ideas?
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