针对误差扩散算法输出中边缘易被模糊的问题,对该算法的基本原理进行了分析,认为原因是误差扩散改变了未处理像素在量化中的取值倾向。 据此设计了一种对图像纹理敏感的误差扩散滤波器。 因该滤波器在平滑渐变区域输出质量较差,为此又设计了基于局部傅里叶分析的滤波器选择算法,分别使用该滤波器与传统滤波器处理纹理丰富区、平滑渐变区。 通过对该算法输出的测试图进行评价,证明了算法对提高半色调输出质量有较明显的作用。

Inspired by the edge blurred in output of error diffusion algorithm, the fundamental of error diffusion algorithm was analyzed; it was considered that the reason of edge blurred is that diffused error changes the edge pixels' value tendency. A new texture sensitive diffusion filter was designed according to the consideration. The quality of the new filter's output is bad on smooth areas, so a filter selection algorithm was designed bases on local Fourier analysis. The new filter and conventional ED filter was applied in texture areas and smooth areas respectively. The output test pattern was evaluated. Subjective evaluation showed that the new algorithm significantly improve the quality of halftone output.