Watermarking using multiple visual channels for perceptual color spaces

This paper presents a perception based watermarking algorithm for perceptually uniform color spaces. The image is watermarked using a blind watermarking scheme in the contourlet domain for the RGB, CIELAB, Y UV and AC₁C₂ color spaces. The contourlet transform is used to decompose the image into directional subbands at multiple levels for all the color spaces. The contourlet transform allows to models the spatial frequency selectivity of the human visual system. The invisibility results of all the color spaces are compared with each other using CIEDE2000 and SSIM metrics. The visual distortion for each color component and its interaction with other color components is considered for all the subbands. Subjective tests are carried out to further validate the objective results. The results of the testing procedures show that the YUV color space is best suited for watermark insertion in terms of human perception.