1. Images are identified using Magic number. If you open a gif file in a text editor, you will notice the magic number representing gif, GIF89a. These numbers are not limited to images alone, even pdf and postscript files can be identified. In fact it can be used to identify most of the file formats
2. ImageMagick is used by flickr.com for their image processing
3. The much used picture of Lena (below) for image processing is the Playboy centerfold picture of the Swedish model, Lenna Soderberg
4. Mencoder is a command line tool for editing movies much like Imagemagick is a command line tool for editing images
5. Mplayer is the close cousin of Mencoder and can be used for viewing movies
6. ffmpeg is another tool for editing movies and is believed to be used in youtube.com to convert the uploaded videos in to flash video (FLV) format.
7. Google has implemented a face recognition in its search. The images of face can be seperated from google image search result by typing "&imgtype=face" at the end of the url.