User blog:WreakerOfClash/How to make pictures high quality?

I've been scrolling through some pages, and I've noticed some drastic quality changes in images, for example:

This is awesome!



Please stop.



Is there a way to make the image above, or any low-rez image higher quality? If so, how? This is something that I want to fix, and I know I probably can, but any advice or knowledge helps.

