@noiob If this is anything close to what you have in mind, this was produced with GraphicConverter, using the Picture: Levels facility. There, you have three pointers you can drag, corresponding to the min/max/median levels in an image, making it simple to bring all "sort of white" shades to just plain white.
https://lgbt.io/media/yiLmk5ccj3a-JDENnLM
https://www.lemkesoft.de/en/products/graphicconverter/download/
(Similar "level crushing" can be found in most graphics apps - GC's just a very handy tool I keep around)
@porsupah heh, I've used Graphic Converter back when our family computer ran Mac OS 8. This is what I ended up producing using OfficeLens and then Gimp
@noiob Oo, that worked too! Mm, GC's been in my toolbox for a long time now.. probably since the days of Mac OS 8.
That's an interesting thought. I like the paradigm of toots *not* being editable, to prevent ninja edits, but perhaps there could be scope for modifiers to existing toots, showing above or below the original, akin to a PS.
@porsupah One of the things I like about Twitter is that it's easy to see wether a tweet is part of a thread. That would probably already help on Masto