Dr. Hany Farid And His Work to Detect Photoshopping
Just now, I finished watching an episode of Nova scienceNOW (yes, that’s how it’s capitalized). Covered in that episode is the work of Dr. Hany Farid and his work to develop software to detect photoshopped images.
One technique that he demonstrated with software is to detect parts of images that are identical. This is to detect whether the clone tool has been used on parts of the image.
Another technique demonstrated is to detect where light is coming from. If two people from two different images are cobbled together into one fake image, it is highly possible that the light sources in the original two images are in different places. This means that the two people are illuminated from different directions, and this is shown on the person. If one person is being illuminated from the left side, and another is being illuminated from the right side, you know that the image was originally two images that had different light sources.
Another way to see the light source, assuming that the image you are testing has at least two people with clearly visible eyes, is to analyze the shape and location of the light being reflected off; that is, the specular highlight. As the eye can act like a mirror, you can see a little bit about the light source, such as the shape of the light source. You can also see how the light source is hitting the person. If one person has a reflection of a square light source (like from a camera flash), and another person has a reflection of a circular light source hitting the person at a completely different angle, there is a good chance that the photo isn’t completely real.
Want to learn more about Hany Farid? You can check out (I grabbed all these links from here):
- Hany Farid’s home page
- Digital Forensics: An Interview with Dr. Hany Farid
- Adobe Tackles Photo Forgeries
- A Conversation With Hany Farid: Proving That Seeing Shouldn’t Always Be Believing
- Digital Doctoring: How to Tell the Real From the Fake (PDF Warning)
So, what’s your prediction on the future of the Internet, photography, and digital photo manipulation?
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