Method for compressing digital values of image, audio and/or video files

Abstract

A method for differential compression of a sequence of digital values adapted to avoid error propagation during restoration of the values.

Description

technical field

[0001] The invention relates to the field of compressing digital values ​​of digital image, audio and / or video files, in particular files comprising sequences of values. Background technique

[0002] The main constraints of the compression method are on the one hand to reduce the octet-sized amount of the original digital file as much as possible by compressing it, and on the other hand to restore a file as close as possible to the original file.

[0003] Certain compression methods allow exact restoration of the original value. This is the case for DPCM modulation. According to this method, the original value (ie, the first value of the original digital file) is preserved, and then each other value is replaced by the difference between this value and the preceding value in the original file. The amount corresponding to the difference is generally smaller than the amount corresponding to the initial value, which makes it possible to obtain a compressed file...

Examples

Embodiment Construction

[0024] According to the present invention, the compression method can be expressed by the following general formula:

[0025] Given an initial sequence S of first values ​​Va,...,Vp,Vq,...,Vz,

[0026] - the compressed value VCa of the first value Va of the sequence S is: VCa=Va; the restored value VDa of the compressed value VCa is: VDa=Ca=Va, and,

[0027] - For a current value Vq different from Va, the sequence S is like this:

[0028] o Given the decompressed value VDp corresponding to the value Vp preceding the current value Vq in the sequence S

[0029] o The compressed value VCq of the current value Vq is:

[0030] VCq=+|round[f(Dq)]|, if Dq>0, and

[0031] VCq=-|round [f(Dq)], if Dq<0,

[0032] Among them, Dq=Vq-VDp

[0033] o The decompressed value VDq corresponding to the current value Vq is:

[0034] VDq=+|round [f -1 (VCq)]|+VDp, if VCq>0, and

[0035] VDq=-|round [f -1 (VCq)]|+VDp, if VCq<0

[0036] o rounded to the nearest integer, and

[0037] o where...

technical field

[0001] The invention relates to the field of compressing digital values ​​of digital image, audio and / or video files, in particular files comprising sequences of values. Background technique

[0002] The main constraints of the compression method are on the one hand to reduce the octet-sized amount of the original digital file as much as possible by compressing it, and on the other hand to restore a file as close as possible to the original file.

[0003] Certain compression methods allow exact restoration of the original value. This is the case for DPCM modulation. According to this method, the original value (ie, the first value of the original digital file) is preserved, and then each other value is replaced by the difference between this value and the preceding value in the original file. The amount corresponding to the difference is generally smaller than the amount corresponding to the initial value, which makes it possible to obtain a compressed file...

Examples

Embodiment Construction

[0024] According to the present invention, the compression method can be expressed by the following general formula:

[0025] Given an initial sequence S of first values ​​Va,...,Vp,Vq,...,Vz,

[0026] - the compressed value VCa of the first value Va of the sequence S is: VCa=Va; the restored value VDa of the compressed value VCa is: VDa=Ca=Va, and,

[0027] - For a current value Vq different from Va, the sequence S is like this:

[0028] o Given the decompressed value VDp corresponding to the value Vp preceding the current value Vq in the sequence S

[0029] o The compressed value VCq of the current value Vq is:

[0030] VCq=+|round[f(Dq)]|, if Dq>0, and

[0031] VCq=-|round [f(Dq)], if Dq<0,

[0032] Among them, Dq=Vq-VDp

[0033] o The decompressed value VDq corresponding to the current value Vq is:

[0034] VDq=+|round [f -1 (VCq)]|+VDp, if VCq>0, and

[0035] VDq=-|round [f -1 (VCq)]|+VDp, if VCq<0

[0036] o rounded to the nearest integer, and

[0037] o where...

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