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07/17/2005 02:14:25 PM · #1 |
I'm still a basic Photoshop user and was wondering how one would go about seeing if a photo has been edited or not.
Say someone asks for a photo which cannot be edited in any way, shape or form (even the smallest of crops or level balancing is off limits), how would one find if a photo is a true original straight from the camera/memory card?
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07/17/2005 03:08:10 PM · #2 |
The first thing we do is verify that the EXIF data saved by almost every camera (and by all the ones we accept) does not indicate that it has been opened and saved by any other software program.
The photographer is required to submit the original and details of the editing done -- the are a variety of ways to compare.
If you are talking about forensic examination for evidentiary purposes, there's a variety of tools for doing that as well, but they are generally expensive and only used by the FBI and other law enforcement or security agencies. |
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07/17/2005 03:32:57 PM · #3 |
| And now with the spectacular XMP files...you even get to know everthing that was ever done to the shot...in detail! |
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07/17/2005 03:37:20 PM · #4 |
One way to do it (assuming the photo is in JPEG format) is to zoom WAY in and observe the pixelation. Most cameras and JPEG compression techniques leave a pretty definate fingerprint. Up close and personal you should be able to detect "grids" of pixels that typically occur in JPEG images. Just browse around and see if there are areas that appear to smooth, too rough, and otherwise out of place with the pixelation fingerprint.
I also read somewhere that Photoshop automatically removes some pixels in JPEG images, making a 8-bit image automatically into a 7-bit image. How you would go about testing for that, I've no idea. If it's even true, I have no idea.
I won't even suggest that it's easy to do, and it's going to take a LONG time.
Clear as mud, right?
Message edited by author 2005-07-17 15:38:04. |
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