A Serpentine Error Diffusion Kernel with Threshold Modulation for Homogeneous Dot Distribution

초록

Digital image halftoning is the process of converting a gray-scale image into its binary equivalent. Error diffusion has been one of the most popular digital halftoning techniques. The quality of binary image generated by the error diffusion method is determined by the error diffusion kernel, the sequence of processing, and the quantization scheme. The serpentine sequence of processing has been proposed for the homogeneous dot distribution. But, the binary image obtained by applying the error diffusion in serpentine sequence often exhibits vertical artifacts, specially at the gray levels of 1/4 and 3/4. In this paper, a serpentine error diffusion kernel is proposed to reduce the vertical artifacts. Also, a threshold modulation technique is proposed to further improve the homogeneity in dot distribution. The experimental results are compared with the corresponding results obtained by the conventional error diffusion techniques.