How to Tell if a Digital Photo has been Photoshopped (and Other Photoshop Disasters)


By web gangsta | Published:

How to PhotoshopFrequent Web Watch readers will remember that we have featured PHOTOSHOP DISASTERS a number of times here, and today will continue that laugh-riot known as really, really bad Photoshopped art.

But one question that is often asked of Web Watch is not so much whether it was easy or hard to point out a Photoshop Disaster.  So here are some tips that show HOW TO TELL IF A DIGITAL PHOTO HAS BEEN PHOTOSHOPPED.

Of course, sometimes it just takes an eyeball.  Take for example, the box cover for the Garmin nüvi 765/765T GPS Unit.  The box is a simple white background with a photo of the GPS unit on it (with its reflection underneath), just like every other Garmin boxed item on store shelves.  The difference on this one versus other Garmin products is that the reflection is not an actual reflection, but just a copy of the existing image that has been rotated 180° from the original.  All other Garmin products took that image and mirrored/flipped it.  

In other words, it don’t look right.

Trust us – if Web Watch can see that the image on the Garmin box isn’t quite right, you should be able to notice it as well.  (The product itself?  No problems at all.  Highly recommended.)

  1. ERROR LEVEL ANALYSIS.  Items that show in bright white have a higher probability of having been altered from the original in the image.
  2. LUMINANCE GRADIENT.  The more smooth edges and blurs you see, the chances of the photo having been altered go up.  Luminance gradient should be noisy and jaggy for an original image.  
  3. PRINCIPAL COMPONENT ANALYSIS.  Shows where image artifacts exist due to file resaves. 
  4. IMAGE NOICE LEVELS, MIN/MAX VALUES. An original image would be very noisy compared to consistent patterns seen in altered images.
  5. DEMOSAIC MODIFICATION ANALYSIS.  Altered photos may have color variation artifacts that do not match the original image

Web Watch will definitely be using these on the next photo we obtain that claims to show the World’s Largest Cat, if only to prove that the image isn’t real before forwarding it on to others.

One thought on “How to Tell if a Digital Photo has been Photoshopped (and Other Photoshop Disasters)

  1. Frank

    A site named pskiller.com can help you find out Photoshopped images. It uses both the exif info and the content of image to find evidence of digital manipulation.

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