Distortion-Free of General Information with Edge Enhanced Error Diffusion Halftoning

Abstract

The error diffusion method is good for reconstructing continuous tones of an image to bilevel tones. However, the reconstruction of edge information by the error diffusion is represented as weak when the power spectrum is analyzed for display error. In this paper, we present an edge enhanced error diffusion method to preprocess original images to achieve an enhancement for the edge information. The preprocessing algorithm consists of two processes. First, the value of difference between the current pixel and the local average of surrounding pixels in the original image is obtained. Second, weighting function is composed by the magnitude and the sign of the local average. To confirm the effect of proposed method, the method is compared with the standard error diffusion and conventional edge enhanced error diffusion methods by measuring various objective measuring criteria including the radially averaged power spectrum density (RAPSD) for display error. The results of comparison demonstrate the superiority of the proposed method over the conventional ones.