HELP! * GREY=local LOCAL HTML version of Foils prepared July 28,1995

Foil 4 Image Compression

From Master Foils for HPDC95 Compression Presentation HPDC95 Pentagon City -- August 1,1995. by Roman Markowski and Geoffrey Fox * See also color IMAGE
lossless - removes the redundancy in the signal; ratio 3:1; the heights of every pixel are perfectly reproduced
lossy - selectively discards "less important" information; ratio 100:1
controversy: the critical feature of any lossy compression is what is important and what is not.
evaluation of several image compression technologies
  • JPEG - the leading standard in visual compression (compresses the image block by block), lossy, full color, block by block
  • JBIG - binary images, lossless, gray scale
  • Fractal - compression slow, decompression fast, lossy, 1000:1, bad quality
  • PhotoCD - Kodak, 96x64, 192x128, 384x256, 768x512, 1536x1024,3072x2048
  • Wavelet - discovered in 1987, lossy, ratio 100:1 and more , compresses the image as a whole

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