A spectrum modification technique for embedding data in images

We propose a method of embedding data in images for secure communication of covert or sensitive information. The method employs an extension of the recent technique of imperceptible embedding in audio signals by inserting tones at perceptually masked frequencies. Instead of detecting visually masked frequencies in two-dimensions, a simpler approach was used by converting an image to a one-dimensional signal. Using the well-established audio frequency masking procedure, audibly masked frequencies at a chosen sampling frequency were determined for each segment or block. Embedding of given data was carried out by modifying the spectral power at a pair of commonly occurring masked frequencies. Preliminary results of embedding 1024 bits of random data in a 256 times 256 pixel black-and-white image show that the spectrum modification technique is viable and simple to process. The technique is useful for hiding a small amount of information on identification card images, credit card logos, etc. Payload can be increased at the cost of an acceptable level of image degradation