Image compression

[Mirh 103]

So.. I don't think this topic should require many presentations.

We already discussed about it here and here

 

And then I even did some discussions on IRC with soeb

I think the 2 points of view are the following:

 

• PNGs are simply bit perfect. Nothing is lost and, given we have no bandwidth nor storage problems, there's no reason for lossy files (when possible to choose between of course)

 

• JPGs can have the same perceived quality of lossless images. As long as you use a proper compression level you can't tell the difference. Advantages? At least 1.5x loading times

You'll say: well what's the matter? I say: when I'm looking the wiki for fixes (not for writing them) I don't care if the edge of the texture of leafs on a tree in the settings background is fuzzy. As long as the image loads in 2 seconds (versus the 15 seconds a 3MB png could require) and the words are clearly readable I'm plain happy.

 

Then if you are purist (no problem in this) I did my own testings and I challenge everyone to notice everything with 97% jpeg quality or higher at 100% zoom level (which is still 2x saving).

With 100% quality I couldn't spot any difference before reaching 200% zoom.

Thanks for reading

 

all testings were done with irfanview for converting and GIMP for comparing

[Marioysikax 89]

Only problem seems to be that mediawiki gives thumbnails in same format as source file which indeed makes page loading in slower connections bit more painful. 
I was thinking is there way to force thumbnails to always render 100% JPG and PNGs only if alpha channel is used or if forced to render as PNG? 

[Mirh 103]

Only problem seems to be that mediawiki gives thumbnails in same format as source file which indeed makes page loading in slower connections bit more painful. 

I was thinking is there way to force thumbnails to always render 100% JPG and PNGs only if alpha channel is used or if forced to render as PNG? 

I guess here it's somewhat explained.

But I don't think the software could be able to notice if there is an alpha channel, so I think the only way to preserve transparency would be to stick with jpeg=>jpeg thumbnails and png=>png thumbnails

[primusauloon 7]

JPEGs with IrfanView, it uses libjpeg-turbo and that's pretty great.