Optimise images.

[grischard]

Saved 12.5 MB out of 56.7 MB. 27.5% per file on average (up to 99.6%)

Description:

For every file, ImageOptim compared the different tools and picked the smallest file that was produced by or by a combination of advpng, pngout and zopfli for PNGs, gifsicle for GIFs, svgo for SVGs or jpegoptim and mozjpeg for JPEGs.

This includes a rather ironic 74.8% change on source/images/blog/2016-08-optimizing-web-app/performance-diagram.png which went from 38237 bytes to 9620 bytes.

No related issues, no code change, no functionality change, no visual differences in images (compression is lossless).

[fabaff]

Images from third-parties (plugins, themes, etc) should be optimized in their source otherwise those images needs to be optimized again when we update. Thus I would limit it to source/images/ source/demo/images/ and source/static/images/.

[grischard]

That makes sense. There's a few stray images in source/demo/ and source/favicon.png and source/static/ too, and it looks like the only two third-party sources are jwplayer/jwplayer and octopress/classic-theme. I'll submit separate PRs there, and update the PR here.

[grischard]

I actually can't find the source for the jwplayer glow theme. It looks like those files haven't been touched since 2014. What do you think we should do?

[grischard]

So both jwplayer/jwplayer#2541 and octopress/classic-theme#6 have been opened, and haven't received any attention :). I'm happy to re-optimise the images and submit a new PR here if and when we update those if upstream ignores them.

@fabaff do you see this as blocking to merge this PR, or could it be merged like that?

[fabaff]

Let's merge it.

Thanks 🐦

[grischard]

Thanks!