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What are some applications to detect altered / photoshopped images? I'm looking at a used item online and get the feeling the seller touched-up the photos (he's a graphics designer, found out from his domain name.

Two things I'm looking for are:

  • reading EXIF data (tried using a Firefox plugin with no success)
  • detecting touch-ups
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8 Answers

up vote 3 down vote accepted

you can use error level analysis (ELA). its free, easy, and relatively straight forward. there is a site you can even point to an url of the image. the result is an image that shows 'new' vs 'old' pixels based on the way .jpg works iirc.

the site is http://errorlevelanalysis.com/

“Error level analysis (ELA) works by intentionally resaving the image at a known error rate, such as 95%, and then computing the difference between the images. If there is virtually no change, then the cell has reached its local minima for error at that quality level. However, if there is a large amount of change, then the pixels are not at their local minima and are effectively original.”

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+1 Not sure this will help, but an interesting approach. –  sleske Aug 10 '10 at 20:53
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:( The site is defunct: "After two years, this image forensics analysis service has been turned off." –  meetar Sep 10 '13 at 21:31
    
There's another similar site here: 29a.ch/sandbox/2012/imageerrorlevelanalysis –  meetar Sep 10 '13 at 22:51
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Here is a link to very informative site about photo analysis with lots of resources about technical and other aspects of photo manipulation.

http://fotoforensics.com/tutorial.php

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A summary, please. The link might break. –  vonbrand Apr 5 '13 at 21:37
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For Exif reading, you can use FastStone Image Viewer. [features, download link 1, download link 2]

a screenshot

alt text

Two screenshots [they differ because they are from different versions of FastStone]

for Detecting touch ups, eye is the best tool, I guess.

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www.isedited.com to check whether a photo is edited in photoshop or not

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BRIGHTEN the image way up, with High contrast if things were pasted badly into the image, it usually leave a edge around it that will show up.

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If there's no EXIF information then it's likely that a photograph is not an original from a digital camera. Some manipulations must have happened.

Detecting changes in a photo is possible with proper forensics software. This is helpful when the image itself isn't showing any traces. The software works by doing pattern recognition, since digital camera's tend to have specific patterns in the pictures they create. Most image manipulations will change these patterns which can be recognised. The software should even be able to give some indications what kind of manipulations have taken place.

Where you can find this software? Well, the FBI, CIA and Interpol will be using it. Don't know if there are any commercial products available but be prepared to pay an arm and a leg for it. (I think it would be real expensive.)

Most image analysis software will be created to recognise shapes and objects. But the kind of software you need is something which can trace manipulations. It's not much more complex than recognising objects, but almost no one is interested in this kind of software. (Except of course to detect if an image is real or fake.)

It is bad that the seller is touching op those images? Maybe he just sharpened the image and removed some things from the background.

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EXIF data won't tell you much - he might have loaded the photo into something like Photoshop just to crop it the way he wanted or some equally reasonable modification.

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A perfectly valid point, but the metadata within could still be useful in determining the history of the image. –  STW Aug 31 '09 at 20:31
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i don't think there is a software solution to prove photo fakery.

my advice: if it doesn't feel right, then don't do it.

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Aww!!! but what's the program that CSI uses?!?! lol, jk... I know there's no silver bullet, but have seen some proof-of-concept apps and was hoping the techniques had trickled down to some open-source utilities –  STW Aug 31 '09 at 20:31
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well, for the sucessful use of photo analasys software you usually need a series of images best taken with the same camera in same environment for comparison. here's a list of programs that may or may not be suitable (some are free): en.wikipedia.org/wiki/List_of_image_analysis_software –  Molly7244 Aug 31 '09 at 20:57
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+1 I totally agree with Molly's advice. –  Lazer Sep 24 '09 at 7:45
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