Patent ID: 11889098
Assignee: DOLBY INTERNATIONAL AB
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 7:
8. A method for decoding a sign-data-hiding enabled data signal representative of at least one image comprising a plurality of coded partitions, the method comprising:
receiving a set of coefficients representing a partition of the image;
identifying a first non-zero coefficient within the set of coefficients;
identifying a last non-zero coefficient within the set of coefficients;
determining a set of modifiable coefficients in the set of coefficients, wherein the set of modifiable coefficients include the first non-zero coefficient, the last non-zero coefficient and all the coefficients between the first non-zero coefficient and the last non-zero coefficient;
determining a count of coefficients in the set of modifiable coefficients;
comparing the count to a plurality of threshold values, including a first threshold value and a second threshold value that is greater than the first threshold value;
in response to determining that the count is greater than the first threshold value but less than the second threshold value, determining that signs of a particular plurality of non-zero coefficients are hidden;
in response to determining that signs of the particular plurality of non-zero coefficients are hidden:
calculating a sum of amplitude information of non-zero coefficients in the set of modifiable coefficients;
calculating, using the sum of amplitude information, parity data;
selecting, based on the parity data, a particular sign configuration from a predetermined plurality of sign configurations;
designating signs in the selected particular sign configuration as signs of a particular plurality of non-zero coefficients; and
dequantizing the set of coefficients representing the partition of the image.