[mapserver-users] differing image size with different mapserver versions

[Richard Greenwood]

On Mon, May 17, 2021 at 7:05 AM Rahkonen Jukka (MML) <
jukka.rahkonen at maanmittauslaitos.fi> wrote:

> Hi,
>
>
>
> Are you sure about “I actually found that 6.4 produced small, aliased
> images with both the GD and AGG drivers”.
>

Yes, I just tested again. In 6.4 I get identical (visually and size) images
with:
   OUTPUTFORMAT
      DRIVER "AGG/PNG" or "GD/PNG".
      . . .

Interestingly, "GD/PNG" does not throw an error in mapserver 7.6 or main
(MapServer 7.7).


> Originally the AGG library could only do anti-aliasing and that affected
> also Mapserver 5
> https://lists.osgeo.org/pipermail/mapserver-users/2007-September/025467.html
> .
>
>
>
> I guess that Mapnik folks have since that added support for controlling
> anti-aliasing with gamma setting http://mapnik.org/mapnik-reference/.
>
> I can see that gamma can be used also with Mapserver
> https://www.mapserver.org/mapfile/outputformat.html
>
>
>
> Have a try with gamma=0. However, Even wrote that turning off antialiasing
> is possible only in master, so perhaps gamma=0 does not work.
>

I tried
   OUTPUTFORMAT
      FORMATOPTION "GAMMA=0"
       . . .

I see no difference in the output image in 7.7 (main) or 7.6 or 6.4. Is my
syntax correct?


>
>  The documentation for Mapserver 5 tells that “All ANTIALIAS keywords are
> now ignored". But the keyword still appears in quite a many places:
>
> https://mapserver.org/search.html?q=antialias
>
>
>
> Would it be time to remove them as well as now not useful references to GD
> renderer (removed by RFC 99 in 2013)?
>

>From my testing it seems that <=6.4 is aliased and >=7.0 is antialiased
regardless of ANTIALIAS options.


> -Jukka Rahkonen-
>
>
>
>
>
> *Lähettäjä:* mapserver-users <mapserver-users-bounces at lists.osgeo.org> *Puolesta
> *Richard Greenwood
> *Lähetetty:* maanantai 17. toukokuuta 2021 15.26
> *Kopio:* mapserver-users at lists.osgeo.org
> *Aihe:* Re: [mapserver-users] differing image size with different
> mapserver versions
>
>
>
> Thanks for the suggestions. The consensus seems to be that anti-aliasing
> is causing the increased size. The documentation here
> <https://mapserver.org/output/antialias.html> says "*Since version 6.0,
> MapServer will produce aliased output for the “gd/” drivers, and
> antialiased output for the “agg/” and “cairo/” ones*" and it's also
> mentioned here
> <https://lists.osgeo.org/pipermail/mapserver-users/2012-April/072011.html> in
> Thomas Bonfort's reply. I actually found that 6.4 produced small, aliased
> images with both the GD and AGG drivers and regardless of my ANTIALIAS
> true/false setting.
>
>
>
> Would anyone consider re-enabling the ANTIALIAS true/false option?
>
>
>
> Thanks,
>
> Rich
>
>
>
>
>
>
>
>
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/mapserver-users
>


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