[mdadm]

This isn't an area that I'm particularly strong in, but I think that the way that imgur compresses images[0] might have a noticeable effect on this.

[0] https://help.imgur.com/hc/en-us/articles/201424706-How-does-...

[dexterdog]

I've run a few photo sites and one of the things I do on all wild incoming JPGs is do a minor compression on them and if that saves more than about 30% on the file size I just use the compressed version. Then anything that's been camouflaged in there gets dropped.