【作者】 肖丽杰；

【导师】 曾平；

【作者基本信息】 西安电子科技大学 ， 计算机系统结构， 2008， 硕士

【摘要】 在二值图像传真和文档管理系统等应用中,半色调图像压缩技术有着极大的实用价值。论文研究了国内外半色调图像压缩的现状,介绍了二值图像和二值文档压缩的国际标准JBIG2,通过分析半色调图像的产生过程和分类,总结得出半色调图像的特征。在研究现有图像压缩算法的基础上,提出了一种基于JBIG2的半色调图像压缩算法,同时提供了解码器可以采用的后期处理操作,以进一步改善图像质量。该压缩算法是有损的,所以必须注意要尽可能地减少在解压缩后的图像中引入人工纹理。实验证明,论文提出的编码方法对周期性半色调图的压缩非常有效,如果周期是完整的并且是整型的,可以得到完全无损的编码。对随机性半色调图像,文中的编码方法取得的压缩率明显地优于无损压缩。同时,该算法也能较好地解决图像质量降低和人工纹理较多的问题。更多还原

【Abstract】 The technique for halftone compression is great valuable in applications of fax in the bi-level image, document management systems, etc. This paper does much research on the status quo of halftone compression at home and abroad, introduces the international standard for compression of bi-level images and bi-level documents- JBIG2, and concludes the characteristics of halftone by analyzing the generation and classification of halftone image. Based on the studying the algorithms available for image compression, an algorithms based JBIG2 for halftone image compression is proposed in the paper, and it is also showed post processing the decoder may apply to increase the quality further. It is noticeable that the coding method has some loss in introducing artifacts in the reconstructed image. Experiments show that the coding method constitutes an effective coding for periodic halftones image, when the period is complete and integer, the coding method can provide perceptually lossless coding, and for stochastic halftones, the coding method provides a significant compression rate compared to lossless coding. Furthermore, the algorithm can improve the image quality by reducing or avoiding artificial texture.更多还原