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

[Even Rouault]

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 
> <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> on 
>> behalf of Richard Greenwood <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>
>> *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 <http://www.greenwoodmap.com>
>>
>>
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>>
>
>
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