I noticed something when making my last Spider-man wallpaper, JPEG artifacts. I hated the way it looked so I decided to switch going forward to PNG. I’m pretty sure most current browsers won’t have a problem with them. I tested a few here and they all worked fine. So starting with the latest wallpaper, they’ll all be PNG. I don’t think I’ll go back and change the older ones because I haven’t noticed a problem like this before.