Board Thread:Support Requests - Designing Your Wiki/@comment-33220655-20180503040552/@comment-168424-20180504000322

Some images lend themselves to looking quite good with high compression. Also, making them slightly transparent can hide flaws. The example you gave actually isn't one of the better ones I've seen and has a big chunk of blank space in the middle. I'm quite proud of the for the Gotham wiki.

You can take an existing image and try to reduce its file size while maintaining its dimensions with various online tools like: http://www.imageoptimizer.net/Pages/Home.aspx

Of course, professional tools like Photoshop work best. I'm spoiled, so I use Photoshop. I've also used GIMP and it works quite well.