Ever seen a photo and wondered if it is real or 'photoshopped'? Been to a dating site and wonder if the photo truly represents the person shown?
Photo Police, a US$1.99 Mac app can often determine if a photo is real or fake. The app works by looking at low-bit pixel data, which can reveal if an image editor has made corrections or changes to software.
Program author Nikolay Kropachev told me that low bit data is usually white noise, and invisible just by looking at an image. The program applies some math and reveals the low bit data; changes can show up very clearly. It can detect blurring that might be used in wrinkle removal, or show where objects were deleted from images.
I tried it on some known fake photos and the changes were quite obvious to Photo Police. I also tried some photos that were purported to be iPhone prototypes, and they also showed some obvious meddling. I also tried it on some images where I used Photoshop content aware fill and it detected some of the changes even though the photo itself looked fine. In other areas of the image Photoshop was able to fool Photo Police. On a photo montage where I did sky replacement Photo Police detected the changes.
The app can't guarantee it will find fakery, because some cameras may generate artifacts, and some image processing operations will make Photo Police think there has been an alteration rather than processing.
In my tests, Photo Police worked quite well, and certainly would give you additional reasons to be suspicious about an image. You can't load raw images into Photo Police, it requires jpeg files.
If you're interested in doing some detective work on images people send you, or things you find on the web, it's a very inexpensive and useful utility. Now I think I'll go chase some Bigfoot and UFO photos.
Check the gallery for some examples of what Photo Police can detect.