I noticed a small discussion on post #6427 regarding how colors change on a large image when viewed in its downscaled state. I noticed a very similar problem with my post #6128 which looks way worse (at least on my screen). In case you don't see what I see, I made this Imgur post which shows how it looks on my screen (before enhancing to original resolution).
Posting this to make sure the issue was known to admins and to open a repository for other instances of the problem. I have absolutely no idea if a practical fix is possible. I'll let you guys worry about that.