HACK THE PLANET!!! Sorry, had a moment there. We're given a widescreen image of Cereal Killer.
I'm going to skip the pain and frustration of the binwalk, strings, steghide, and everything else. You need ONE thing for this challenge. Brightness.
Pop this image into GIMP (A staple for image analysis), Go to Colors > Brightness-Contrast > Edit These Settings as Levels > then play with the top slider to get the flag.