There are a few lossy transformations you can make to an image before saving it as a PNG that result in a lossy compressed PNG that's smaller than the image oth

There are a few lossy transformations you can make to an image before saving it as a PNG that result in a lossy compressed PNG that's smaller than the image otherwise would be. This idea was used a ton with GIFs, it's less popular with PNGs, though. pngquant is one tool I know of that does this. That said, I have no clue if such techniques would result in a smaller image than this approach.