<title>Noncausal error-diffusion method for edge enhancement</title>

Abstract

Various modifications to the Floyd-Steinberg's error diffusion algorithm have been proposed to reduce the undesirable artifacts or to enhance the edges on the error diffused image. Most of the existing error diffusion techniques utilize the error diffusion kernel defmed on the causal image plane with respect to the raster scanning directions. In this paper, an error diffusion kernel containing non-causal neighbors is proposed for edge enhancement. The error diffusion kernel for individual gray level is first estimated by minimizing the error criterion defined for the input gray level ramp image and its output binary image. The proposed error diffusion kernel is then calculated by taking an average of the estimated error diffusion kernels representing mid-tone gray levels. Experiments are performed to examine the proposed error diffusion method. Experimental results indicate that the binary images obtained by the proposed error diffusion kernel exhibit the enhanced edges compared to those from the existing error diffusion techniques.