An image steganography implementation for JPEG-compressed images

A method of implementing image steganography in a color image for applications such as covert communication via the Internet and 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 secure or confidential data is carried out by modifying the spectral power at a pair of commonly occurring masked frequencies. Compressing the data-embedded image to standard JPEG coding enables its transmission via the Internet. Experimental results show that the technique is simple to implement and causes barely noticeable distortion in the stego image. Using an oblivious technique and a key consisting of the frequencies where the spectrum is modified, successful data retrieval even at low level noise levels and at low-loss compression has been achieved. Higher payload of hidden data can be obtained at a cost of perceptibility of embedding. Lossy JPEG compression, however, leads to low payloads.