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

[Seth G]

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. 

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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
> 

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