pngquant optimization

[lollo78]

Hi guys, considering that pngquant is supported
92e77f2
What do you think about to compress all the actual PNGs and upload them again on libretro-thumbails?
Could we define the compression parameters to use?

[stubl]

I like the png format as it is because the images can be used with other frontend programs

wouldnt all future uploads need to be re-converted too by other contributors? dont know if its worth it

[kivutar]

Other frontends are certainly using the generic libpng that supports pngquant, isn't it?

[Alcaro]

Other frontends are certainly using the generic libpng that supports pngquant, isn't it?

Ew, dependency.

pngquant emits standards-complaint PNGs that work in any PNG reader. There's no need to worry about compatibility one way or the other.

[Tatsuya79]

What setting are you using? I tried "speed 1" and the loss is quite visible compared to a good jpg.
Isn't jpg going to get supported?

[Enverex]

What's the point in using PNG if you're just going to lossy recompress them? Run them through optipng sure, but not pngquant.

[lasers]

Some thumbnails are not displaying. libretro/RetroArch#3932. Is it a result of using some png compression like optipng or pngquant? Any solution?

[RetroUp]

I've optimized all images. No visible difference. Average 60% file size reduction. I'll upload next week. There are no issues with thumbnails in RA or other frontends.

Compressing assets with transparent backgrounds can cause major issues. They need to be done more manually but can be done.

[RobLoach]

We're now running https://imgbot.net/ across all repos at https://github.com/libretro-thumbnails