I’m all for catching bad guys, and this story from Foxnews.com could well lead to the capture of a child abuser. Which is nice. But, I have to admit, it’s the thought of what technique they are using to help identify the guy that is really intriguing to me.

See, as a designer, when I’m working on photos, I use layers, adjustment layers, and a variety of other techniques to avoid “destroying” pixels. That is, original images are made up of pixels; when a designer makes changes to those pixels, he or she can destroy the original image. That could be a problem if the changes end up being unacceptable, if the client wants to step back to a more natural look, or for a raft of other reasons. When I first start working on a picture, I’ll make a safety copy of the original and, opening the file in Photoshop, I’ll start working on a copy of the original layer just so that I ensure the integrity of some untainted copy of that first file.

Doing things like blurs and twirls are destructive--they change the pixels so much that the original mapping is gone. Which is still true, but maybe a little less true than I though.

In a first, Interpol appealed Monday for public help to identify a suspected pedophile shown in photos posted on the Internet sexually abusing young boys in Vietnam and Cambodia.

German specialists have produced identifiable images of the man from the original pictures, in which his face had been digitally blurred, the international police organization said. But the man’s identity and nationality remain unknown, prompting Interpol’s worldwide appeal.

Visiting the link, you’ll see a before and after set of pictures--one where the suspect’s face had been twirled, and one where the image specialists had reconstructed the original. While there are still significant artifacts from the image manipulation, the reconstructed image is relatively clear and, I would imagine, could quickly lead to identifying the criminal.

When the original file is twirled, the section of pixels that is changed streaks, bleeds, and bends until all that is left are stretched lines of the original colors. Un-twirling isn’t as simple as just sending the pixels back in the other direction--all that will do is cause new streaks, bleeds, and bends in the opposite direction. It won’t even come close to undoing the damage that the first manipulation caused.

Again, or so I thought. Assumptions can really kick your ass, can’t they?

Below is a set of images. The first image is the original. The second image has had a twirl of 449º applied in Photoshop. The third image has had a twirl of -449º applied to the second image.

As you can see, the image is still distorted--there are streaks and artifacts and detail has been lost--but has become recognizable again. It wouldn’t save me from a needing to step back from a mistake, but it is a much easier process than I had thought. Criminals beware.

You learn something new every day.

Read the rest. And, if you think know the guy, contact the authorities and help put him in jail.