Since when did GIFs have notably better compression than PNGs? (Perhaps the issue is that these are badly-generated PNGs, and simply loading them into something that knows how to write PNGs and saving them again would produce similar gains?)
It’s the color palette; you can indeed save them as 256-color PNGs and get the same file size reduction. I suggested converting to GIF because it’s more likely that the OP knows or can figure out how to do that, than that he has & knows how to use a tool which can save palette-reduced PNGs.
Since when did GIFs have notably better compression than PNGs? (Perhaps the issue is that these are badly-generated PNGs, and simply loading them into something that knows how to write PNGs and saving them again would produce similar gains?)
It’s the color palette; you can indeed save them as 256-color PNGs and get the same file size reduction. I suggested converting to GIF because it’s more likely that the OP knows or can figure out how to do that, than that he has & knows how to use a tool which can save palette-reduced PNGs.
Ah, I see. Yes, that would be an improvement, maybe 10% as good as just making the stuff be text in the first place.