Method for compressing digital values of image, audio and/or video files
View Patent ↗A method is disclosed for compressing a sequence of initial digital values into a compressed sequence of compressed values, intending to restore these values into a decompressed sequence of decompressed values. For a first initial value of the sequence, the compressed value of the first initial value is equal to the first initial value and the decompressed value of the compressed value of the first initial value is equal to the first initial value. For each current initial value, the method includes calculating the difference between the current initial value and the decompressed value of the initial value immediately preceding the current value, calculating a compressed value of the difference using a complementary compression function, calculating the decompressed value corresponding to said current initial value, applying the three preceding steps to the immediately following value if there is one, and constituting the compressed sequence of the compressed values, each corresponding to a respective initial value.
1. A method for compressing a sequence of initial digital values in a first digital image, audio and/or video file into a compressed sequence of compressed values in a second digital image, audio and/or video file, intending to restore compressed values into a decompressed sequence of decompressed values in a third digital image, audio and/or video file, comprising:
for a first initial value of the sequence, setting the compressed value of the first initial value equal to said first initial value and setting the decompressed value of said compressed value of the first initial value equal to said first initial value, and,
for each current initial value, the following steps are carried out, in order:
calculating a difference between the current initial value and the decompressed value of an initial value immediately preceding the current initial value;
calculating a compressed value of said difference using a complementary compression function;
calculating the decompressed value corresponding to said current initial value;
applying the steps of calculating a difference, calculating a compressed value and calculating a decompressed value, to an immediately following value if there is one; and,
constituting the compressed sequence of the compressed values, each corresponding to a respective initial value.
2. The method according to claim 1 , in which the compressed value is rounded to the nearest whole number.
3. The method according to claim 1 , further comprising keeping, in the compressed value, a sign that is the same as a sign of the difference.
4. The method according to claim 1 , in which the complementary compression function is an nth root function where n>1.
5. The method according to claim 4 , in which the complementary compression function is the “square root” function.
6. The method according to claim 4 , in which the complementary compression function is the “cubic root” function.
7. The method according to claim 1 , in which the complementary compression function is a division by a constant C, where C>1.
8. A method for decompressing a sequence of digital values compressed using the method according to claim 1 , comprising:
for a first compressed value of the compressed sequence, setting the decompressed value is equal to the first compressed value,
for each current compressed value performing the following steps in order:
calculating a corresponding decompressed value by applying, to the current compressed value, an inverse function of the complementary compression function and then adds a preceding decompressed value;
applying the step of calculating the corresponding decompressed value to an immediately following compressed value if there is one; and,
constituting a decompressed sequence of decompressed values, each corresponding to a respective initial value.
9. The method to claim 8 , wherein the inverse function has a sign that is the same as a sign of the compressed value.