Lossless compression: Difference between revisions

Revision as of 18:09, 5 October 2024

Revision as of 09:31, 7 October 2024

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A hierarchical version of this technique takes neighboring pairs of data points, stores their difference and sum, and on a higher level with lower resolution continues with the sums. This is called [[discrete wavelet transform]]. [[JPEG2000]] additionally uses data points from other pairs and multiplication factors to mix them into the difference. These factors must be integers, so that the result is an integer under all circumstances. So the values are increased, increasing file size, but hopefully the distribution of values is more peaked. {{Citation needed|date=December 2007}} <!-- can someone please explain JPEG2000 for dummies!? Wavelets are fun if taken as continuous real valued function. But all this math for simple integer linear algebra? -->

{{angle bracket|The adaptive encoding uses the probabilities from the previous sample in sound encoding, from the left and upper pixel in image encoding, and additionally from the previous frame in video encoding. In the wavelet transformation, the probabilities are also passed through the hierarchy.<ref name="Unser" />

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=== Historical legal issues ===