In 2006, spammers started in a big way to use image spam to try to push through all of their stuff. While this technique is still used today, it isn't quite as effective because spam filters caught up.
One technique that Microsoft developed is called Shingling. That's where the image is broken up into a series of smaller segments, called shingles. The noise is removed and hashes compared for those microsegments. Given two images, it was possible to compare if two images were more or less the same. Of course, they weren't exactly the same, they were slightly different but all spammers were doing was inserting random noise, or rotating the image or phase shifting it. By ignoring the noise one could compare and match two images.
Recently, I came across the Photosynth application from Microsoft Live Labs. This is an application where you can upload your pictures from a trip and it will attempt to create a panoramic shot of all the images. I would guess that some of the image shingling techniques are used by looking at things like edge detection. While I was in China, I knew about this application so I took a few pictures to test this out. I didn't completely succeed in getting all of the overlap to work, but some of it turned out all right. Below is a shot of Shanghai, China:
Anyhow, it's a cool application. From now on, for my future trips I shall take shots of some neat places with this app in mind.
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"it's a cool application"
May or may not be, doesn't work here (FireFox 3/Ubuntu 32bit).
Well I read the specs and never saw that any version of Linux was supported.
Minimum System Requirements
Important: Photosynth makes heavy use of your graphics hardware. If you have an older graphics system, Photosynth may not run. Also, Photosynth requires that your graphics acceleration be set to full.
Operating System: Only Windows XP (SP2 or SP3) and Windows Vista are supported at this time. Running Windows on a Mac? Photosynth runs under some VM configurations. Check out our help site for an updated list.
Web Browser: Internet Explorer 7, Firefox 2, and Firefox 3
Memory: 256 MB of memory is a bare minimum; 1GB is recommended.
Graphics: Minimum 32MB of graphics memory required, 64MB or more is recommended. Photosynth runs on some DirectX6 capable cards and all DirectX7 cards.
You find this a lot on some web pages. you rollover the image in certain spots and find Easter eggs or hidden links. This was actually something big back in the late 90's. Interesting description. Love your blow!