[Live-demo] compressing images with pngquant

Johan Van de Wauw johan.vandewauw at gmail.com
Mon Jun 8 11:05:38 PDT 2015

On Sat, Jun 6, 2015 at 2:16 AM, Angelos Tzotsos <gcpp.kalxas at gmail.com> wrote:
> On 06/05/2015 10:25 PM, Johan Van de Wauw wrote:
>> On Thu, Jun 4, 2015 at 8:33 PM, Johan Van de Wauw
>> <johan.vandewauw at gmail.com> wrote:
>>> Hi all,
>>> I've been experimenting with pngquant [1] to reduce the size of our
>>> png images in the documentation. This implements a lossy compression
>>> method, but all images I tried came out just fine.
>>> In total, we could save about 36Mb by using this compression on all
>>> files. I believe this is significant enough to do the change for most
>>> files, especially since they are accessed also over the web by people
>>> reading the quickstart.
>>> I prepared a branch which contains the compressed images at:
>>> https://github.com/johanvdw/OSGeoLive-doc/tree/compresspng
>>> I made a single commit per image, so if we merge we can still roll
>>> back specific images easily.
>>> In fact, on github, you can watch the images side by side or as a slide
>>> over.
>> During the meeting last night I proposed fixing only those images
>> where the difference was most significant (>50% reduction in size and
>> files of at least 32Kb).
>> The results are here:
>> https://github.com/johanvdw/OSGeoLive-doc/tree/compresspng
>> The result can be downloaded as a package from:
>> https://launchpad.net/~johanvdw/+archive/ubuntu/osgeolive-docs-compressedpng
>> And it can be previewed at:
>> http://gisky.be/osgeolive-docs/en/index.html
>> In total we save some 34 Mb, most of which is preserved when
>> compressing the files.
>> Since I did not see any image which is not good I propose to merge this.
>> Kind Regards,
>> Johan
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>> http://live.osgeo.org
>> http://wiki.osgeo.org/wiki/Live_GIS_Disc
> First of all, thank you Johan for your excellent work on creating the deb
> packaging for the documentation.
> Looking at the demo site, I think that all the images are not scaled
> properly (set to 100%?).
> Any idea what is wrong?

Not really. Did we use the default sphinx from ubuntu trusty for our
previous builds?
When I try building on debian from the same source, images are scaled.

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