小波零树编码在图像压缩及其去噪中的应用研究

【作者】 胡峰；

【导师】 陆锦辉；

【作者基本信息】 南京理工大学 ， 信号与信息处理， 2003， 硕士

【摘要】 图像压缩编码技术是多媒体通信技术中的关键技术，近年来各种压缩标准应运而生(例如JPEG2000和MPEG-4)，这两个标准都推荐使用小波变换技术来编码。本文主要研究了小波零树编码在图像压缩及其去噪中的应用，提出了一些改进算法；最后对各种基于小波零树思想的压缩编码方法进行比较和总结。 本文首先阐述了各种图像压缩方法和视频图像压缩标准，用于图像压缩的小波变换基本理论；其次介绍了基于小波零树编码思想的两种成功的图像编码算法嵌入式零树编码算法EZW和多层次零树编码算法SPIHT。本文提出了两种改进算法，算法一：DPCM、零树和游程相结合的改进算法；算法二：DPCM、零树和矢量量化相结合的改进算法；仿真结果表明这两种改进算法无论从客观信噪比还是从主观质量都取得了很好的效果，从而证明改进方案是有实际意义的；然后是含噪图像的小波零树编码去噪研究，软门限去噪以后采用第一种改进算法对图像进一步压缩，解压后的仿真结果显示噪声得到了很好的去除；最后是对基于零树编码思想的各种编码方法进行总结、分析和比较。更多还原

【Abstract】 Image compression coding plays a very important role in the multimedia communication technology.Various compression standards,such as JPEG2000 and MPEG-4, have appeared.Wavelet transform technology is used both in JPEG2000 and MPEG-4.In this paper,firstly,I mainly discuss the problem about wavelet zerotree in image coding and two improved algorithms are proposed.Secondly,we compress image combined with deleting noise by wavelet zerotree algorithm.Lastly,several compessing methods based on wavelet zerotree idea are compared and summarized.Firstly,all kinds of image compressing methods and image coding standards are reviewed. Furthermore I introduce the elementary wavelet theory. Secondly,two classical wavelet image coding algorithm based wavelet zerotree idea are introduced and two improved algorithms are proposed.The first algorithm is that we combine runlength coding and zerotree coding in which LL band coefficients are coded lonely with DPCM.The second algorithm is the zerotree algorithm with vector quantization is combined with LL band coefficients alone coding with DPCM.The simulating results show they can get better performance both in PSNR and subjective quality.Thirdly, we make research on how to compress image combined with deleting noise by zerotree algorithm.First we use soft-threshold method to denoise image with noise,and then the first improved zerotree algorithm is used to compress image.Simulating results show that the subjective quality of the decoded image is good.Lastly,we compare,analyse and summarize all kinds of compressing methods based on wavelet zerotree idea.更多还原