Optimal Parameters for Error-Diffusion Halftoning with Bilateral Filter

We propose a procedure for determining the parameters in the bilateral filter (BF) used for the error-diffusion halftoning where pixels are scanned in the ascending order of errors. In this halftoning, binarization errors produced at each pixel are diffused using the BF which contains two parameters, one of which is a spatial coefficient and another is for the signal intensity. The optimal values of these two parameters are determined by maximizing the PSNR of an output binary images against their input images. It is shown by experiments that the optimal value of the signal coefficient is slightly negative in contrast to popular usage of BF where the signal coefficient is usually set to a positive value.