Tuesday, May 09, 2006

The most famous face in image processing

In 1973, some computer scientists were working on processing images. They had become bored with their old images and were looking for an image to scan in and work on. Just then, someone walked in with a Playboy. To get a picture with the pixels and dimensions they wanted, they cropped a page at the woman's shoulders (and above) and scanned it onto some old hardware.

This is Lenna.

For no explicable reason (except perhaps the missing half of the picture), the image became a phenomenon in the image processing world. You see it in all kinds of applications. Anyway, a few years back, the centerfold got to meet a bunch of her number one fans at an imaging conference. It's a heartwarming story of geeks in love.

I have a confession, though. The image of Lenna above is not the original; for one thing, it's not in color. But for another thing, the original black-and-white didn't have 6K of secret embedded data in it. Welcome to the world of image steganography: the art and science of concealing the fact that a secret message exists. If cryptography is like the lock, then steganography is like the swiveling fireplace.

That's what I've been working on for the past few months. Here's to a good milestone: a working program.

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