Patent ID: 7974477

Claim:
A method for embedding data into a JPEG-encoded image, comprising: deriving from the JPEG-encoded image a histogram of values of JPEG image coefficients, the histogram having a frequency associated with each value; setting a threshold value, T, so that a number of JPEG image coefficients whose values lie in the range from −T to T is greater than a number of bits to be embedded in the image; identifying or creating at least one histogram pair within the range of values from −T to T, wherein a histogram pair is a pair of neighboring values in the histogram for which one of the histogram frequencies is zero and the other is non-zero; for at least one JPEG image coefficient having a value corresponding to the non-zero frequency of the histogram pair, modifying the image coefficient to have the value of the histogram pair associated with the zero frequency if a data bit to be embedded has a first bit value selected from the set {0,1} and not modifying the image coefficient if the data bit to be embedded has a second bit value, different from the first bit value, selected from the set {0,1}, to obtain at least one processed image coefficient; and outputting a processed image including the at least one processed image coefficient; wherein the above operations are to be performed using one or more processing devices.