Hi,

I made a very short test with Mapnik 2.2.0 demo maps. Mapnik can create png 
images either with AGG or with Cairo and I compared the 256 colour demo maps 
obtained by running the Mapnik c++ version of "rundemo" test program.  Image 
sizes were

AGG 112 kb, went down to 104 kb by optimizing with Irfan view PNGOUT plugin
Cairo 105 kb, went down to 97 kb by optimizing with Irfan view PNGOUT plugin

Perhaps it would be worth having a try with Cairo 8-bit png for small output 
size if we can use it with Mapserver.

-Jukka Rahkonen-


________________________________
Lähettäjä: [email protected] 
[[email protected]] käyttäjän Richard Greenwood 
[[email protected]] puolesta
Lähetetty: 7. kesäkuuta 2013 23:33
Vastaanottaja: mapserver
Aihe: [mapserver-users] Fwd: RFC99: Remove GD support in 7.0

Sorry - posting back to list...

---------- Forwarded message ----------
From: Richard Greenwood 
<[email protected]<mailto:[email protected]>>
Date: Fri, Jun 7, 2013 at 2:32 PM
Subject: Re: [mapserver-users] RFC99: Remove GD support in 7.0
To: thomas bonfort <[email protected]<mailto:[email protected]>>





On Fri, Jun 7, 2013 at 2:00 PM, thomas bonfort 
<[email protected]<mailto:[email protected]>> wrote:
(posting back on list)

On 7 June 2013 21:24, Richard Greenwood 
<[email protected]<mailto:[email protected]>> wrote:
I have continued to use GIF rather than 8bit PNG because the GIF is smaller. 
Often by as much as 15%. Is that expected? Is there anyway to get PNG down to 
GIF size? I certainly understand the rationale for eliminating GD but I am 
discouraged by the prospect of larger image sizes.

I don't think that the gif vs. png format is relevant concerning file size when 
encoding the same pixel data. However, the quantity of information to encode in 
an antialiased image rendering is higher than in a non antialiased one, thus 
the higher file size when using agg/png8 vs. gd/gif. Even if we were to add a 
an agg/gif format, you would still be seeing this size overhead.

Yes, I think I sort of knew that but thanks for clarifying it.

To put this bluntly, if the 15% overhead is important for you, you would have 
to stick with gd aliased rendering and the 6.4 release. I would also like to 
put this in context: a 15% overhead compared to the 2001 (2005?) outputs does 
not seem like a big deal given the evolution of available bandwidth since that 
time.

I work in some pretty rural areas where bandwidth is still limited. And when 
considering bandwidth we need to keep mobile applications in mind alos. 
MapServer has always been synonymous with speed and from the user experience 
perspective speed is determined by the whole pipeline.

We've been supporting this technologically obsolete rendering mode for many 
years now, but imo it's time to move on.

I completely respect that. I was mainly wondering if there was a way to reduce 
the anti-aliasing (and consequently the rendered image file size) when using 
AGG, which I'm sure sounds like a pretty silly question given the "A" in AGG.

Thanks for your reply and for all of the work that you do on the MapServer 
project.

Rich



regards,
thomas


Rich


On Fri, Jun 7, 2013 at 7:27 AM, thomas bonfort 
<[email protected]<mailto:[email protected]>> wrote:
Devs and Users,

Please have a look at RFC99 
(http://mapserver.org/development/rfc/ms-rfc-99.html). I am particularly 
interested in use-cases that would not be supported if GD were to be removed.

cheers,
Thomas

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--
Richard Greenwood
[email protected]<mailto:[email protected]>
www.greenwoodmap.com<http://www.greenwoodmap.com>




--
Richard Greenwood
[email protected]<mailto:[email protected]>
www.greenwoodmap.com<http://www.greenwoodmap.com>



--
Richard Greenwood
[email protected]<mailto:[email protected]>
www.greenwoodmap.com<http://www.greenwoodmap.com>
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