基于多级误差扩散算法的网目调图像伪轮廓研究

为研究多级误差扩散后网目调图像的伪轮廓现象，本研究在分析伪轮廓产生机理的基础上，对阶调偏亮、平衡、偏暗的三幅图像分别采取不同的量化阈值进行多级误差扩散网目调处理，探讨其分布特点。比较结果表明，伪轮廓与图像阶调层次分布及量化阈值有很大的关系。针对中间调伪轮廓更为明显的特点，提出调制中间调区间量化阈值的新思路。计算结果表明，该方法对多级误差扩散网目调图像的伪轮廓有较好的改善作用。

Research on Pseudo-Contour of Halftone Images Based on Multi-level Error Diffusion Algorithm

To research the distribution characteristics of pseudo - contour in Multi - level Error Diffusion （MED） halftone images, based on the analysis of generation mechanism of MED, three images which were partial bright, normal and dark separtely, were processed by multi - level error diffusion halfloning algorithm with different quantization threshold values. The compared results showed that pseudo - contour related with the gradual level distribution of the images and quantization threshold values. On this basis, a new method was put forward to modulate the quantization threshold values in midtones where pseudo - contour appeared obviously. The calculating results showed that it is effective to eliminate the pseudo - contour in multi -level error diffusion halftone images.