Information hiding can be performed under the guise of a digital image. We consider the following scenario: Alice and Bob share an image and would like to use it as a cover image to communicate a message m. We are interested in answering two questions: <i>What is the maximum amount of information that can be sent for a given level of degradation to an image? </i>and <i>How can this level of efficiency be achieved in practice?</i> We require the recovered message to be the same as the embedded one.
Our model begins with Alice compressing a message to obtain a binary sequence with uniform distribution. She then converts the binary sequence into a <i>Q</i>-ary sequence having a pre-defined distribution, and finally adding each symbol to a pixel. The distribution of the <i>Q</i>-ary sequence is chosen such that the amount of information is maximized for a given value of the signal to noise ratio. Bob recovers the sequence by subtracting the image data, and then converting the <i>Q</i>-ary string into the original binary string.
We determine the optimal distribution analytically and provide a graphical representation of the variation of the amount of information with signal-to-noise ratio when the size of the alphabet, <i>Q</i>, varies.
Conference Committee Involvement (2)
Security, Forensics, Steganography, and Watermarking of Multimedia Contents X
28 January 2008 | San Jose, California, United States
Security, Steganography, and Watermarking of Multimedia Contents IX