A technique for imperceptible embedding of data in a color image

A method of embedding data in a color image for applications such as authentication of an employee carrying a picture identification card is described. By converting the color image to a one-dimensional signal in red, green, or blue, audibly masked frequencies in the 1-D signal are determined for each segment or block. Embedding of data, such as key biometric information of the person, is carried out by modifying the spectral power at a pair of commonly occurring masked frequencies. Preliminary results show that the spectrum modification technique is simple to process and causes barely noticeable distortion in the embedded image. Using an oblivious technique and a key consisting of the frequencies where spectrum is modified, successful data retrieval with no bit errors has been achieved. Embedded image corrupted by low level noise still retained the hidden data with low bit errors. Higher payload of hidden data can be obtained at a cost of perceptibility of embedding.