A halftone watermarking method of high quality,robustness,and capacity flexibility is presented in this paper.An objective halftone image quality evaluation method based on the human visual system obtained by a least-mean-square algorithm is also introduced.In the encoder,the kernels-alternated error diffusion (KAEDF) is applied.It is able to maintain the computational complexity at the same level as ordinary error diffusion.Compared with Hel-Or using ordered dithering,the proposed KAEDF yields a better image quality through using error diffusion.We also propose a weighted lookup table (WLUT) in the decoder instead of lookup table (LUT),as proposed by Pei and Guo,so as to achieve a higher decoded rate.As the experimental results demonstrate,this technique is able to guard against degradation due to tampering, cropping,rotation,and print-and-scan processes in error-diffused halftone images.