reduce file size of images in themes

[chrisraven]

I tried to reduce file size of images from themes provided with jQuery UI, and it looks like it is possible to save some KBs. I tried ​http://www.punypng.com/ and ​http://www.smushit.com/ysmush.it/ online compressors (there are others), both gives some size reduction. According to the sites, this is lossless reduction and everything should works fine after it, even in IE6.

My results are:
base theme:
punypng - 2.9 KB reduction
ysmush.it - 952 B reduction

black-tie theme:
punypng - 3.7 KB reduction
ysmush.it - 1.26 KB reduction

I believe, that every theme can be downsized.
If there are no side efects (I didn't find any), then maybe it should be good to save those couple KBs.

Best regards
ChrisRaven

[rdworth]

Good idea but we need to have our bases covered

1. This would have to well tested to ensure the images remain PNG/8
2. These images get passed through ThemeRoller+ImageMagick before they end up in a theme. There's a chance they end up large(r) again after that. As ThemeRoller is being re-written, makes more sense to focus such optimization efforts on the new version, not existing.
3. To make a change like this, we'll need a full end-to-end test with all the theme images (post ThemeRoller) ensuring pixel perfect color rendering of all images (this can be done with an rgba image diff of before and after images) as well as a visual test in IE6 of before and after

[Jörn Zaefferer]

New ThemeRoller is still using old ThemeRoller to generate images, so that pipeline didn't change at all. Its still unclear if or when we can get rid of that by switching to the image-free CSS framework that jQuery Mobile uses.

Does ThemeRoller actually use the images from the base theme? If not, we could just optimize those and leave the ThemeRoller output as-is.

Will ask Rafael to take a look when he's back.

[Scott González]

This was done in ​b7d0c701c79c751f80e2f4058f7a4c3a17262815.