[mapserver-users] PNG Optimization

[thomas bonfort]

Cedric,
Mapserver currently doesn't support png options, although this
souldn't be to difficult to add as a FORMATOPTION (at least for the
non GD renderers).
You should note that the quality of the compression you apply to pngs
has a non trivial effect on the overall rendering time, so we can't
just add maximum compression by default.

ps: you can see the effect of png compression schemes (on throughput
and image size) on this small benchmark I ran for mod-geacache. the
use case is the on the fly merging of two 256x256 png tiles:
http://mod-geocache.googlecode.com/svn-history/r69/trunk/static/benchmark.png

regards,
thomas


2010/12/10 Cédric MOULLET <cedric.moullet at gmail.com>:
> Hi,
> We are using MapServer to generate tiles and the following ouptut format is
> used:
>
> OUTPUTFORMAT
>  NAME "pnga"
>  MIMETYPE "image/pnga"
>  DRIVER "AGG/PNG"
>  EXTENSION "png"
>  IMAGEMODE "RGBA"
>  TRANSPARENT TRUE
>  FORMATOPTION "INTERLACE=OFF"
> END
>
> We observe that the size of the tiles can be reduced by a at least factor 2
> if we use a tool like optipng.
> Is it possible to configure MapServer in order to optimize the file output
> (and for example use optipng)  ? Or do you see another way to optimize the
> image (I'd like to do that on the MapServer side in order to avoid a
> postprocessing) ?
> Thanks in advance for any hints.
> Cédric
>
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