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Interpol Unscrambles Doctored Photo In Manhunt

Posted by kdawson on from the blur-schmlur dept.

jackpot777 writes in with an AP story out of Paris reporting that Interpol has distributed photos of a man suspected of sexually exploiting children. The images were recovered from pictures taken off the Internet in which the man's face had been blurred using something like Photoshop's Filter > Distort > Twirl tool. German police were able to recover recognizable images of the man, whose identity and nationality are not known. Interpol would not discuss the techniques used to recover the images. jackpot777 writes: "It does show one interesting facet of internet privacy that has also been noted with topics ranging from reading blurred check numbers in images to Google's plan to blur out license plate and face data for Street View. And that is: blurring is not the same as completely obscuring. As computers become more adept at extrapolating data of different types, your identity isn't safe unless you completely cover all those identifying features."

6 of 370 comments (clear)

  1. Pictures by avij · · Score: 5, Informative

    The pictures can be seen on Interpol's site.

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    1. Re:Pictures by mikael · · Score: 4, Informative

      A convolution filter would allow you to sharpen or blur the image, or maybe even pick out high frequency detail.

      The spiral distort effect is simply a mathematical function to map one point in a rectangular mesh to another. You basically convert integer pixel coordinates into a floating-point coordinate system with the origin at the centre, apply a rotation based on the distance from the origin, convert back into integer pixel coordinates and transfer the pixel data.

      Consequently, since every pixel is remapped to a new position, the transformation can be reversed.

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  2. Interpol not the ones to descramble by packeteer · · Score: 4, Informative

    From the interpol web page it says:

    These pictures have been produced by specialists from Germany's federal police force, the Bundeskriminalamt, working from originals found on the Internet, which had been digitally altered to disguise the man's face.

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  3. The actual AP article by avij · · Score: 4, Informative

    .. can be read here.

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    Follow your Euro bills at EBT
  4. Blurring different from twirling... by Max+Romantschuk · · Score: 5, Informative

    A twirl is essentially shifting pixels around an image, and is designed to keep as much information as possible.

    A blur on the other hand, especially a gaussian blur, will mix pixels together in such a way that any recovered image will be one of many possible outcomes.

    Then again, removing information, by pixellating for example, would be best.

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  5. Comment removed by account_deleted · · Score: 4, Informative

    Comment removed based on user account deletion