[KevinH]

But can you and most people actually see a difference without "super zooming"? Seriously? I can not. And I really doubt anyone is going to be super zooming in on any of these images in Sigil's user guide. Given how easy it is to recreate these images as screenshots and how often they will need to be updated as gui interfaces change on each platform, if and when desktops go to 8k or 16k resolutions, we just recreate them.

The much much smaller file size with indexing and restricting it to a palette of 256 colours seems to be a very good tradeoff as smaller file sizes pays off in a multitude of ways when loading, and caching images in both an e-reader and in Sigil itself.
Especially when differences can only be seen when super zooming in.

I see no significant differences on a 4k+ retina display with these images at normal display sizes so the statement that at "nearly all of them" need to be reverted is just not something I can agree with at all.

So we must agree to disagree here.