[mapserver-users] RGBA transparent images?

[Stephen Woodbridge]

If I want to generate RGBA transparent images using AGG, what should my 
OUTPUTFORMAT block look like?


I was using this one for 8-bit images, but the anti aliasing was 
creating blackish artifacts along the rendered lines. Is there a way to 
avoid them?

   OUTPUTFORMAT
     NAME "agg_qn"
     DRIVER "AGG/PNG"
     EXTENSION "png"
     MIMETYPE "image/png"
     IMAGEMODE RGBA
     TRANSPARENT ON
     FORMATOPTION "INTERLACE=false"
     FORMATOPTION "QUANTIZE_NEW=ON"
     FORMATOPTION "QUANTIZE_FORCE=ON"
     FORMATOPTION "QUANTIZE_DITHER=OFF"
     FORMATOPTION "QUANTIZE_COLORS=37"
     FORMATOPTION "TRANSPARENT=ON"
   END

Trying 32bit RGBA:

   IMAGECOLOR 0 0 0

   OUTPUTFORMAT
     NAME "agg_qn"
     DRIVER "AGG/PNG"
     EXTENSION "png"
     MIMETYPE "image/png"
     IMAGEMODE RGBA
     TRANSPARENT ON
     FORMATOPTION "TRANSPARENT=ON"
   END

Generated black backgrounds and not transparent. Is it as simple as 
removing the IMAGECOLOR? I didn't try that.

-Steve W