Objective distortion measure for binary images

This paper describes an approach to evaluate the distortions introduced by changing individual pixels in the binary document image. The approach calculates the distortion by combining the change of smoothness with the change of connectivity. It is different from traditional distortion measures, such as PSNR and SNR, which do not correlate with human visual perception for binary image. PSNR and SNR only concern about how many pixels have been changed. The new approach considers not only how many pixels have been changed but also where the pixels have been changed. Simulation results show that the new distortion measure correlates well with human visual perception and its application in watermarking can be effective.