[mapserver-users] Slow output to PNG format with Mapserver 6.4

[Rahkonen Jukka (Tike)]

Hi,

We were running speed tests with Mapserver 6.4 on Linux 64-bit and we found that WMS output to GIF and JPEG was much faster (+30% or more) and much more stable (less variation in response times) than png8 outputformat. I was surprised because I have not observed the same on Windows. However, I have not tested GIF output on Windows seriously. I tried it on Linux because I had a feeling that our Mapserver wan unnecessary slow with png.

Is this natural? Changing the png compression rate did not make much difference in speed, it mostly affected the size of generated files. My outputformat is taken from Mapserver documentation.

OUTPUTFORMAT
      NAME 'AGG_Q'
      MIMETYPE "image/png"
      DRIVER "AGG/PNG"
      EXTENSION "png"
      IMAGEMODE RGB
      FORMATOPTION "QUANTIZE_FORCE=ON"
      FORMATOPTION "QUANTIZE_DITHER=OFF"
      FORMATOPTION "QUANTIZE_COLORS=256"
  END

-Jukka Rahkonen-