[mapserver-users] anti-aliasing (was differing image size with different mapserver versions)

Richard Greenwood richard.greenwood at gmail.com
Tue May 18 09:50:01 PDT 2021


Thanks to several helpful replies to my previous thread I know that the
increased image size between MapServer 6 with the GD driver and MapServer 7
with the AGG driver is due to differences in anti-aliasing (and lack of) in
the two drivers. (AGG features anti-aliasing and sub-pixel resolution
<https://en.wikipedia.org/wiki/Anti-Grain_Geometry>).

Gamma setting from 0-1 affects the size of a filled polygon layer by a
factor of almost 3x. But gamma has no effect on text, lines, and polygon
outlines. So images comprised of these types of features are approximately
2x larger with the AGG/PNG8 driver than with the GD/GIF driver.

Where else should I be looking to reduce my images sizes? I serve rural
areas with poor internet so in my case, smaller image sizes are more
important than higher quality images.

Thanks,
Rich

-- 
Richard W. Greenwood, PLS
www.greenwoodmap.com
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