HVS-based Imperceptibility Measure of Watermark in Watermarked Color Image

Imperceptibility of embedded watermark reflects the fidelity of watermarked image. Based on the color masking and Watson´s JND (just noticeable differences) model, a calculation method of JNCD (just noticeable color differences) is proposed. Then the masking weight for each element of color image is calculated using the JNCD and a new quality measure of watermarked color image is proposed, i.e. CPSNR (color image peak signal to noise ratio). The quality of watermarked color image calculated by CPSNR is closer to the sensitivity of human vision than PSNR.