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

[Richard Greenwood]

Bob - I think GD was quite unpopular with the developers. Thomas Bonfort
was pretty adamant about removing it. I'm hoping that there may be options
in AGG.

Seth - FORMATOPTION "COMPRESSION=9" only reduced the size by about 3% in my
lines and text test case.

Even - the default AGG/PNG8 has QUANTIZE_FORCE=on and QUANTIZE_COLORS=256.
I think I remember you saying somewhere that reducing the number of colors
mostly just reduced the pallet size and that's pretty much what I see. e.g.
reducing the pallet from 256 to 15 colors reduces the image size by about
15% in my lines and text test.

Thanks all for the suggestions.
Rich


On Tue, May 18, 2021 at 11:49 AM Even Rouault <even.rouault at spatialys.com>
wrote:

> Forcing paletted images using QUANTIZE_FORCE=on and decreasing the number of colors with QUANTIZE_COLORS can also help:
>
>  FORMATOPTION "QUANTIZE_FORCE=on"
>  FORMATOPTION "QUANTIZE_COLORS=200"
>
> Le 18/05/2021 à 19:30, Seth G a écrit :
>
> I've not used it but the following might help for the AGG/PNG driver:
>
> FORMATOPTION "COMPRESSION=9"
>
> https://mapserver.org/mapfile/outputformat.html
>
> The default is 6.
>
> --
> web:http://geographika.co.uk
> twitter: @geographika
>
>
> On Tue, May 18, 2021, at 7:16 PM, Basques, Bob (CI-StPaul) wrote:
>
> All,
>
>
>
> I know the GD stuff has been a long running conversation in the MapServer
> realm, but does this indicate that maybe discussing something on adding GD
> back in might be prudent?  Or are there methods to get down to these
> previous files sizes with the newer approaches?
>
>
>
> I have the same concerns related to image size from the performance side,
> and running on Mobile in our case.
>
>
>
> Bobb
>
>
>
>
>
> *From: *mapserver-users <mapserver-users-bounces at lists.osgeo.org>
> <mapserver-users-bounces at lists.osgeo.org> on behalf of Richard Greenwood
> <richard.greenwood at gmail.com> <richard.greenwood at gmail.com>
> *Date: *Tuesday, May 18, 2021 at 11:50 AM
> *To: *"mapserver-users at lists.osgeo.org" <mapserver-users at lists.osgeo.org>
> <mapserver-users at lists.osgeo.org> <mapserver-users at lists.osgeo.org>
> *Subject: *[mapserver-users] anti-aliasing (was differing image size with
> different mapserver versions)
>
>
>
> *Think Before You Click: *This email originated *outside *our
> organization.
>
>
>
> 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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>
>
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-- 
Richard W. Greenwood, PLS
www.greenwoodmap.com
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