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

[Steve Lime]

If you don't care about quality then JPEG is an option... ;-) I also wonder
if there are ways to create true 8-bit output in other ways. No way GD
comes back.

On Tue, May 18, 2021 at 1:12 PM Richard Greenwood <
richard.greenwood at gmail.com> wrote:

> Oops - typo there, reducing the colors from 256 to *125* reduced the
> image size by about 15%.
>
> On Tue, May 18, 2021 at 12:11 PM Richard Greenwood <
> richard.greenwood at gmail.com> wrote:
>
>> 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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>>>
>>> -- http://www.spatialys.com
>>> My software is free, but my time generally not.
>>>
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>>
>>
>> --
>> Richard W. Greenwood, PLS
>> www.greenwoodmap.com
>>
>
>
> --
> Richard W. Greenwood, PLS
> www.greenwoodmap.com
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