But it no longer can be analyzed for pixel values that have scientific meaning. One of the first techniques that was used to move images around the Internet was designed to make the picture as small as possible. That technique added three letters to each image file so people would recognize a picture file from a text file. This file shrinking technique works great for maintaining the beauty of a picture while making the file as small as possible. Yes, GIFs, and another great file shrinker called JPEG, are the image files of choice.
Smaller files transfer from one computer to another more quickly.
And this is preferred on the net. The standard file format for the Mac is called a PICT file. The Image Processing for Teachers project has some great free sample lessons. The one most germane to Live From Hubble Space Telescope is a lesson you can get that lets the kids image process the Moon IO and its spectacular Volcanoes. Bringing Image analysis, digital video and the net to the class.