Posted: 4/24/2006 9:29:16 AM EDT
Does anyone have a link to a simpleton discussion on how the JPEG picture format works? I'm curious as to how it works, but whenever I do a search on it, all I can find is a ridiculously complictaed technical discussion on Discrete Cosine Transform functions and DC Coefficients.  Any ideas? |
Pretty much my understanding of it too. As you dial up the compression, the more the software will say "That's close enough" and just make anything relatively close to a certain color, that color. Extreme examples will show banding where the color jumps from one shade to another. |
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JPG is an image compression technique of taking a line in an image and compressing it to its like color pixels. Think about it like an old type writer and taking all the abcdefgijklmnopqrstuvwxyz and taking the same letters in a line and compressing it to one letter then having a table of where in the line the other like letters go. |
Thanks for the links y'all. Here's what I was able to come up with for my research paper (copyright roboman, 2006) 
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That's what LOSSLESS compression schemes, like GIFs, TIFFs, and PNGs do. JPG is LOSSY compression, meaning that the compression algorithm actually changes pixel colors compared to the original image, in order to reduce the file size. And the amount of data lost is adjustable (as is the color space), so that you can adjust how much data is lost/changed to improve the compression rate and reduce file size. This is important, for example, in web graphics, which need to be as small as reasonably possible so that they transfer quickly (use less bandwidth) and don't tie up the web server too long. MPEG video and MP3 audio are other popular examples of lossy compression, where quality is reduced somewhat in exchange for much smaller file sizes. -Troy |