Color image watermarking with high imperceptibility and
robustness capabilities is still an emerging topic in the field of multimedia
copyright protection. A novel approach for robust and semiblind
watermarking of still color images in the wavelet domain is proposed.
The proposed technique utilizes the human visual system characteristics,
and an innovative watermark weight-calibrating procedure to
create various watermarks at different classes of the color image under
consideration. It decomposes the input color image into specific
classes where each class is applied to an appropriate watermarking
procedure that takes into account its grayness and/or chromaticity
behaviors on a pixel-wise and color permissibility basis. The experimental
results have shown that the proposed technique exhibits very
high imperceptibility (80.1 to 89.2 dB) and is sufficiently robust to
guard against JPEG compression, additive noise, filtering, moderate
cropping, scaling, and other common image manipulations.