[–] Splooge 0 points 8 points 8 points (+8|-0) ago (edited ago)
Error Level Analysis. It examines images for evidence of manipulation. The result is what you see in the linked image. If it were photoshopped, we'd see white/grey artifacts around the modified areas, but we don't, so the odds of this being unmodified are good.
You're looking for consistent distribution of lights and darks. In this case, if you look around the thigh area, which would typically be the "target" in a case like this, you can see all the levels are consistent where they should be.
[–] mmmmdonuts 0 points 2 points 2 points (+2|-0) ago
Interesting! I know some people I swear photoshop their pics and I might use this to check it out... thanks Splooge!