Improving quality of error-diffusion using random-function based combination of algorithm

In this paper, we describe the method of random-function based combination of algorithm to improve the quality of variable-coefficient error-diffusion. To remove the visual artifacts, we propose a variable-direction E-D algorithm which can generate none artifact images on the intensity of V-C-E-D's artifacts area. Using random-function and a set of thresholds to control the selection of the algorithm. Experiments were done on the critical level to get the optimal thresholds. The result of the algorithm combination is an artifact-free halftoning in the full range of intensities. Artifacts of V-C-E-D and V-D-E-D are all removed. Fourier spectra analysis of the selected key density further supports this conclusion.