MULTI-BIT INFORMATION HIDING USING OVERLAPPING SUBSETS

摘要

Methods and devices for reconstructing coefficient levels from a bitstream of encoded video data for a coefficient group in a transform unit. Sign bits are hidden in the parity of partially overlapping subsets of a set of coefficients. This enables the hiding of multiple sign bits per coefficient group. Other information bits may be hidden instead of sign bits in some cases.

主权项

1. A method of decoding a bitstream of encoded video in a video decoder to reconstruct coefficients of a set, the set comprising a first nonempty subset of coefficients and a second nonempty subset of coefficients, the method comprising:
for each coefficient of the second subset, determining a respective absolute value of that coefficient; determining a first sum of the respective absolute values of the coefficients of the second subset; determining, for a first coefficient belonging to the first subset, a parity of the first coefficient based on the first sum; if the determined parity is odd, then determining that a flag which indicates whether the absolute value of the first coefficient is greater than zero or equal to zero is not present in the bitstream and decoding a first flag which indicates whether the absolute value of the first coefficient is greater than one or equal to one; and if the determined parity is even, then decoding a flag which indicates whether the absolute value of the first coefficient is greater than zero or equal to zero and if it is greater than zero, determining that a flag which indicates whether the absolute value of the first coefficient is greater than one or equal to one is not present in the bitstream and decoding a flag which indicates whether the absolute value of the first coefficient is greater than two or equal to two.