I heard a possible rumor that this is a glitch for only certain users
supercat1230234 is the only user I've met with this glitch so far...

The invert effect

I think at least

Invert would look something like this.

Oh ok

This should be

Huh... interesting. It works, I don't know if a lot of users would think of putting grayscale all the way to 200 so it is possible there might be another way. Cool though.

Effect glitch.