Abstract
In this paper, a least distortion data hiding approach is proposed for halftone image watermarking. The impacts of distortion and tonality problems in halftoning are analyzed. An iterative linear gain model is developed to optimize perceptual quality of watermarking halftone images. An optimum linear gain for data hiding error diffusion is derived and mapped into a standard linear gain model, with the tonality evaluated using the average power spectral density. Our experiments show that the proposed linear gain model can achieve an improvement of between 6.5% to 12% as compared to Fu and Au’s data hiding error diffusion method using the weighted signal-to-noise ratio(WSNR).