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Common Graphic File Formats for Images

521 bytes added, 02:38, 7 July 2014
/* JPG / JPEG: Joint Photographic Experts Group Format (JFIF) */
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A JPEG bitstream is a sequence of data chunks, each chunk starts with a marker value.  For compression JPG mostly utilizes Baseline DCT / Huffman, providing lossy compression.  The image is a continuous tone photo with five or more bits per channel.  When decoded, the image appears from top to bottom like a windowshade rolling down. Compression is variable and governed by a number of parameters with typical settings providing from 10:1 to 20:1 reductions in file size.Baseline JPEG compression is the most common and is nearly synonymous with the use of the term JPEG.  A JPEG bitstream is a sequence of data chunks, each chunk starts with a marker value.  For compression JPG mostly utilizes Baseline DCT / Huffman, providing lossy compression.  The image is a continuous tone photo with five or more bits per channel.  When decoded, the image appears from top to bottom like a windowshade rolling down. Compression is variable and governed by a number of parameters with typical settings providing from 10:1 to 20:1 reductions in file size.''Note that although Baseline JPEG lossy compression is what is widely used there are other more obscure implementations including a lossless JPEG (lossless coding mode).  It should also be noted that when using baseline JPEG compression, setting the quality to 100% in software when saving an image still results in image quality loss.  It is not implied that such a setting would switch to a lossless coding mode.''
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