JPEG2000算术编码器的改进算法与实现

作为新一代静止图像压缩标准的JPEG2000标准拥有压缩比高,支持多分辨率等优点。JPEG2000的编码方式采用了嵌入式码块编码(EBCOT)方式,在编码过程中采用了MQ算术编码。文中分析了它对内容单一、信息量少图像编解码的不足,针对这些不足提出了一种对MQ算术编码器流程的改进算法。这种算法提高了JPEG2000对简单图像压缩的PSNR值,使解码后的图像更加清晰。     

基于子带金字塔结构的彩色图像小波编码

本文改进了分层树集分割算法(SPIHT),重新设计了一种子带金字塔的数据结构来组织图像的二维小波变换系数,既减少了存储空间又加快了编码速度.在彩色图像的YUV空间按位平面的顺序依次对YUV三个分量编码,输出颜色分量完全嵌入式的码流.实验结果表明改进后算法对彩色图像的编码能获得很好的率失真性能,而且适用于高分辨率、不规则图像的编解码.     

简析JPEG2000的核心算法——EBCOT

JPEG2000是国际标准化组织(ISO)指定的新一代静止图像压缩标准。它作为JPEG的升级版，向下兼容，具有比JPEG更高的压缩率，同时具有一些新的特征。这里主要介绍了JPEG2000中的核心算法EBCOT(embedded block coding with optimized truncation)—基于优化截断的嵌入式块编码算法。以此阐述了JPEG2000压缩标准新的特征以及与现有压缩标准相比显示出来的优越性能。     

基于3D-SPIHT的立体视频图像压缩编码

该文提出一种新的立体视频编码方案:在辅助序列中进行视差补偿预测和三维等级数集合分区(3D-SPIHT)编码,3D-SPIHT算法建立在真三维小波分解基础上,通过定义一种新的时空方向树结构,实现了静止图像SPIHT算法的三维扩展,实验结果表明该方案的编码性能略高于传统方案,具有较低的计算复杂度,所产生的嵌入式辅助序列码流,可根据通道带宽自适应调整输出码率,最大限度地提高辅助序列的质量。     

小波图像编码研究与应用的新进展

首先回顾了现代小波编码的发展历程，以嵌入式零树小波编码（EZW）算法和分层树中的集分割（SPIHT）编码算法为例，对其基础理论和基础思路进行了深入阐述，介绍了该领域的一些新的应用和研究成果，并分析指出了小波图像编码算法进一步改进的研究方向。     

适于嵌入式系统的视频去块效应算法

为了消除基于块编码的低码率视频压缩技术中"块效应"现象,针对嵌入式多媒体处理器的结构提出了新的自适应滤波消除块效应算法.此算法在TI OMAP5910平台上实现,实验表明它有效提高客观PSNR值和改善块效应现象.同时为了满足嵌入式系统在不同应用场合下的实时处理需求,在本算法的基础上提出计算复杂度动态可调方案.     

一种改进的嵌入式零树小波编码算法

嵌入式零树小波编码算法是基于小波变换的一种图像压缩方法,它可以实现渐进编解码,进行有损或无损压缩,具有较高的压缩比和图像恢复质量.全文在研究嵌入式零树小波编码算法及原理的基础上,表述了算法的应用过程,阐述了具体的实现思路,指出了其不足之处,并在原来方法的基础上进行了有效改进,具有比较好的效果.     

基于三维小波变换嵌入式视频压缩算法的研究

本文把二维图像的等级树集分割编码方法(SPIHT)推广应用于三维的视频编码中,提出了一种用于三维视频序列图像的扩展等级树集分割编码方法.此方法所编码码流是嵌入式码流,在解码端可随意截取一段码流解码以达到所要求的码率和视频质量.另外此方法无需进行运动补偿,降低了算法的复杂度.通过理论分析和仿真实验得出,此方法有很好的编码效率,但对于帧内图像较复杂的序列,编码效率有所下降.     

数字水印技术和JPEG2000编码过程的统一

本文提出了一种将数字水印技术和JPEG2000压缩编码实现过程相统一的方法。JPEG2000是新一代静止图像压缩编码标准,它是在EBCOT(优化截断嵌入式块编码)算法的基础上形成的。本文结合JPEG2000格式压缩码流的形成过程,以位平面为处理平台嵌入水印,根据需要在图像解码端检测水印,实现水印技术和编码算法的统一。与传统方法相比,该方法节省了将嵌入水印的图像进行二次压缩的运算成本,提高了检测水印的效率:充分利用了JPEG2000编码的优越性,在图像进行渐进的有损传输或在较高的压缩比时仍能有效地检测到水印,具有较高的鲁棒性。     

面向大容量数据实时传输的块间4纠删编码

现有纠删编码由于编解码运算复杂度及编码数据大小的限制,很难适用于面向大容量数据块或数据分组的实时传输中。在奇偶校验码的基础上,结合有限域GF(28)域的特性,提出一种新的面向大容量数据块实时传输的块间4纠删编码方案。该编码方案对一组连续的数据块使用4个冗余数据块,即可容忍任意4个数据块同时差错。编解码运算的复杂度与数据块的大小成线性关系,对数据块的大小没有限制。编码具有MDS性质,在同等冗余条件下达到最佳的纠删能力。理论和实验分析表明:该编码方案最大能够对连续27个数据块进行块间纠删编码。     

基于小波变换的嵌入式图像编码算法的综述

小波变换所具有的良好的空间一频率局部化特性给基于此的图像编码算法提供了广阔的发展空间。其中嵌入式图像编码算法因其提供的良好特性成为静止图像编码新标准JPEG2000的基础。本文对基于小波变换的嵌入式图像编码方法近十年来的研究进行了较全面的综述,着重分析了几种典型算法的原理、实现和编码性能,并探讨了此方法可能的发展方向。     

匹配视觉生理机制的方向分解图象编码

本文对方向分解图像编码进行了系统研究。与Kunt方案相比,提出了更有效的边缘信息选择和编码算法,改进了内插方法和模型,并采用了新的方向滤波器设计方法,基于上述改进,建立了一套完整的匹配视觉生理机制的方向分解图像编码算法。系统模拟实验表明,当数据压缩比近60:1时,采用本方案仍能获得较好的图像质量。     

新一代的静止图像压缩标准JPEG2000

JPEG2000是国际标准组织ISO／ITU－T为适应21世纪图像压缩应用而制定的静止图像压缩标准。目前,该标准的第一部分（PART1）已基本完成。本文介绍了这一即将完成的新标准的特点及应用场合,阐述了JPEG2000图像编码系统的实现过程,对其中采用的基本算法和关键技术进行了描述。     

Image segmentation for compression of images and image sequences

Region-based image coding schemes, the so-called second generation techniques, have gained much favour in recent years. For still picture coding, they can increase the compression ratio obtained by transform coding by an order of magnitude, while maintaining adequate image representation. The success of these techniques relies on the ability to describe regions in an image succinctly by their shape and size. The algorithms presented describe methods for segmenting images. Unlike most other region based algorithms, these algorithms incorporate knowledge of the border coding process in deciding how to partition the image. The extension from single image compression to sequential image compression is also considered. A new, efficient segmentation scheme is proposed that exploits temporal redundancies between successive images, and reduces some problems associated with error accumulation in error images     

JPEG2000及其编码系统的实现

随着多媒体技术应用领域的扩大，小波图像压缩研究日趋成熟。因此，国际标准化组织(ISO)指定了新一代的图像压缩标准：JPEG2000。首先介绍了JPEG2000的特点，然后介绍了JPEG2000的编码系统的实现过程，重点讨论了JPEG2000的技术核心：离散小波变换和EBCOT技术。最后，通过使用VC^ 6．0实现JPEG2000的编码算法，并对两种图像压缩格式进行了比较，给出了一个详细的实验结果。     

Source coding of speech and video signals

Some digital source coding techniques for speech and video are reviewed. Predictive coding of speech, multipulse and code-excited coders and frequency-domain coders are discussed and compared for the coding of speech signals, and intraframe and still image coding and interframe coding are examined for the coding of image and video signals. The emphasis is on those algorithms that offer high compression while maintaining the perceptual quality of the source signals are discussed. Some algorithms that are general waveform coding algorithms and do not strictly depend on the input source are included     

Embedded foveation image coding

The human visual system (HVS) is highly space-variant in sampling, coding, processing, and understanding. The spatial resolution of the HVS is highest around the point of fixation (foveation point) and decreases rapidly with increasing eccentricity. By taking advantage of this fact, it is possible to remove considerable high-frequency information redundancy from the peripheral regions and still reconstruct a perceptually good quality image. Great success has been obtained previously by a class of embedded wavelet image coding algorithms, such as the embedded zerotree wavelet (EZW) and the set partitioning in hierarchical trees (SPIHT) algorithms. Embedded wavelet coding not only provides very good compression performance, but also has the property that the bitstream can be truncated at any point and still be decoded to recreate a reasonably good quality image. In this paper, we propose an embedded foveation image coding (EFIC) algorithm, which orders the encoded bitstream to optimize foveated visual quality at arbitrary bit-rates. A foveation-based image quality metric, namely, foveated wavelet image quality index (FWQI), plays an important role in the EFIC system. We also developed a modified SPIHT algorithm to improve the coding efficiency. Experiments show that EFIC integrates foveation filtering with foveated image coding and demonstrates very good coding performance and scalability in terms of foveated image quality measurement.     

Motion compensated sequence coding using image pyramids

Image coding using image pyramids is a technique originally developed for still pictures. The authors report an image sequence coding technique with motion compensation using image pyramids, which gives greater data compression than conventional motion estimation algorithms.<>     

小波变换帧间预测医学图像编码

该文报道了一种新的医学图像编码方法,称为具有运动补偿的小波变换帧间预测医学图像编码。模拟结果表明:这种新算法比现有的同类算法有更好的性能。     

Joint source-channel coding using real BCH codes for robust image transmission.

In this paper, a new still image coding scheme is presented. In contrast with standard tandem coding schemes, where the redundancy is introduced after source coding, it is introduced before source coding using real BCH codes. A joint channel model is first presented. The model corresponds to a memoryless mixture of Gaussian and Bernoulli-Gaussian noise. It may represent the source coder, the channel coder, the physical channel, and their corresponding decoder. Decoding algorithms are derived from this channel model and compared to a state-of-art real BCH decoding scheme. A further comparison with two reference tandem coding schemes and the proposed joint coding scheme for the robust transmission of still images has been presented. When the tandem scheme is not accurately tuned, the joint coding scheme outperforms the tandem scheme in all situations. Compared to a tandem scheme well tuned for a given channel situation, the joint coding scheme shows an increased robustness as the channel conditions worsen. The soft performance degradation observed when the channel worsens gives an additional advantage to the joint source-channel coding scheme for fading channels, since a reconstruction with moderate quality may be still possible, even if the channel is in a deep fade.