Quality access control of compressed color images using data hiding

This paper proposes a scheme for quality access control of discrete cosine transform (DCT  ) based compressed color image(s) using data hiding. The goal of access control is achieved by transforming the original image into the luminance, chrominance-blue and chrominance-red (YCbCrYCbCr) color space followed by modulating the coefficients of luminance (Y  ) and/or chrominance-red (CrCr) channels. The amount of modulation and the information about the specific channels to be modulated are contained in a key K  , which is supplied by the owner/service provider. This key and the original image are used to create a content dependent key. The content dependent key is then embedded into the chrominance-blue (CbCb) component as watermark using spread spectrum modulation. This watermark information is used for demodulation that leads to the access control through the restoration of the relative quality of the images. Simulation results show that the proposed scheme provides an effective quality access control for the compressed color image without decreasing the compressibility of the standard JPEG coding scheme. The performance of the proposed method is also compared with the few other methods.