Kompresja danych

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Kompresja danych ... accept the convention that
the word "compression" be encoded as "comp". ...
ZIP file format ... both the sender and receiver
of the information understand the encoding
scheme ... Lossless vs. lossy compression
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Kompresja danych
stratna
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Claude E. Shannon, 1948 A Mathematical Theory
of Communication
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Kompresja danych bezstratna
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MP3 digital audio encoding and lossy compression
format, 1991, ISO ... psychoacoustic models ...
tradeoffs between data size and sound quality ...
bit rate 128 - 320 kbit /s ... compression
artifacts ... sound of applause it is hard to
compress because of its randomness and sharp
attacks
CD parameters 44.1 kHz, 2 channels, 16 bits per
channel -gt 1411.2 kbit/s
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JPG Joint Photographic Experts Group 1994, ISO
10918-1 method of compression for photographic
images lossy compression ... from RGB into a
different color space called YCbCr ... discrete
cosine transform MPEG Moving Picture Experts
Group
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kompresja 0 plik 16,2KB
kompresja 20 plik 9,94KB
JPG
kompresja 50 plik 9,29KB
kompresja 100 plik 8,37KB
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Szum
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JPG kompresja 100
bmp 24bit - 29,3 KB 256kolor 10,8 KB
16kolor 5,19 KB
JPG kompresja 20
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GIF Graphics Interchange Format ... limited to
a palette of 256 colours or less ... Unisys ...
owned some patents to key parts of the GIF
compression technology, and has started demanding
fees from every company whose software uses the
(freely available) GIF code
bmp 24bit - 29,3 KB gif 14,0 KB
bmp 256kolor 10,8 KB