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This article answers Frequently Asked Questions about JPEG image compression. This is part 1, covering general questions and answers about JPEG. Part 2 gives system-specific hints and program recommendations. As always, suggestions for improvement of this FAQ are welcome. New since version of 14 March 1999: * Expanded item 10 to discuss lossless rotation and cropping of JPEGs. This article includes the following sections: Basic questions:  What is JPEG?  Why use JPEG?  When should I use JPEG, and when should I stick with GIF?  How well does JPEG compress images?  What are good "quality" settings for JPEG?  Where can I get JPEG software?  How do I view JPEG images posted on Usenet? More advanced questions:  What is color quantization?  What are some rules of thumb for converting GIF images to JPEG?  Does loss accumulate with repeated compression/decompression?  What is progressive JPEG?  Can I make a transparent JPEG?  Isn't there a lossless JPEG?  Why all the argument about file formats?  How do I recognize which file format I have, and what do I do about it?  What other common compatibility problems are there?  How does JPEG work?  What about arithmetic coding?  Could an FPU speed up JPEG? How about a DSP chip?  Isn't there an M-JPEG standard for motion pictures?  What if I need more than 8-bit precision?  How can my program extract image dimensions from a JPEG file? Miscellaneous:  Where can I learn about using images on the World Wide Web?  Where are FAQ lists archived? This article and its companion are posted every 2 weeks. If you can't find part 2, you can get it from the archive at rtfm.mit.edu (see " Where are FAQ lists archived?"). Part 2 changes very frequently; get a new copy if the one you are reading is more than a couple months old.