An algorithm for coding video signal based on 3-D wavelet transformation

This paper presents an algorithm for coding video signal based on 3-D wavelet transformation. When the frame order t of a video signal is replaced by order 2, the video signal can be looked as a block in 3-D space. After splitting the block into smaller sub-blocks, imitate the method of 2-D wavelet transformation for images, we can transform the sub-blocks with 3-D wavelet. Most of video signal energy is in the decomposed low-frequency sub-bands. These sub-bands affect the visual quality of the video signal most. Quantizing different sub-bands with different precision and then entropy encoding each sub-band, we can eliminate inter- and intra-frame redundancy of the video signal and compress data. Our simulation experiments show that this algorithm can achieve very good result.     

A lossless compression algorithm of remote sensing image for space applications

A simple and adaptive lossless compression algorithm is proposed for remote sensing image compression, which includes integer wavelet transform and the Rice entropy coder. By analyzing the probability distribution of integer wavelet transform coefficients and the characteristics of Rice entropy coder, the divide and rule method is used for high-frequency sub-bands and low-frequency one. High-frequency sub-bands are coded by the Rice entropy coder, and low-frequency coefficients are predicted before coding. The role of predictor is to map the low-frequency coefficients into symbols suitable for the entropy coding. Experimental results show that the average Comprcssion Ratio （CR） of our approach is about two, which is close to that of JPEG 2000. The algorithm is simple and easy to be implemented in hardware. Moreover, it has the merits of adaptability, and independent data packet. So the algorithm can adapt to space lossless compression applications.     

一种基于提升小波的快速图像融合算法

提出了一种基于提升小波变换的快速多聚焦图像融合方法。首先利用提升小波算法将原始图像分解为四个子带:LLLHHLHH后将代表三个方向高频细节子带LHHLHH采用提升小波反变换,以获得各方向子带的高频细节图像,采用高斯核权重算法计算所得到的高频细节图像的非均匀加权区域能量,再根据基于能量的图像融合规则得到最终融合图像。对比了几种多聚焦图像融合方案的性能,实验结果表明,在融合效果相当的情况下,文中方法比现有方法在处理速度上有明显的优势。     

基于小波变换的自适应多模红外小目标检测

小波变换是一种有效的红外小目标检测方法。然而,在不同的子带、不同方向上,信号和噪声所呈现的特性不同,采用单一的阈值往往无法得到一个令人满意的检测结果。针对这一情况,提出了一种基于小波变换的自适应多模红外小目标检测算法。该算法可以根据不同尺度和方向上噪声的分布自动调整阈值,使得检测结果更加有效。其中分别采用了自适应Bayes Shrink阈值和广义交叉验证阈值处理每个子带的小波系数,接着再利用处理后的系数重构小波图像,最后通过一个简单的全局阈值分割得到红外小目标。实验结果表明,与对照方法相比,所提出的算法具有更好的检测性能和鲁棒性。     

基于DCT变换的QWT域改进的图像盲水印算法

针对数字图像的版权保护,基于离散余弦变换和四元数小波变换,提出了一种新的改进的盲水印算法,先根据待嵌入水印的大小对载体图像进行四元数小波变换,获得与幅值和相位信息相对应的4幅低频子带,然后对每个低频子带分别进行全局离散余弦变换,最后通过修改两个随机子带中特定位置上DCT系数的大小关系嵌入水印,利用分阶线性Logistic映射产生的混沌序列预处理经Arnold置乱后的水印信息和确定水印的嵌入位置.实验结果表明,该算法对添加噪声、JPEG压缩、滤波和亮度及对比度调整等攻击都具有很强的鲁棒性.     

离散小波变换域非负张量分解的高光谱遥感图像压缩

该文提出一种基于非负张量分解的高光谱图像压缩算法。首先将高光谱图像的每个谱段进行2维离散5/3小波变换,消除高光谱图像的空间冗余。然后将所有谱段的每级小波变换的4个小波子带看作为4个张量。对每个小波子带张量采用改进HALS(Hierarchical Alternating Least Squares)算法进行非负分解,来消除光谱冗余和空间残余冗余,同时保护了光谱信息。最后,将分解的因子矩阵进行熵编码。实验结果表明,该文提出的压缩算法具有良好压缩性能,在压缩比32:1~4:1范围内,平均信噪比高于40 dB,与传统高光谱图像压缩算法比较,平均峰值信噪比提高了1.499 dB。有效地提高了高光谱图像压缩算法的压缩性能和保护了光谱信息。     

A Motion Picture Coding Algorithm Using Adaptive DCT Encoding Based on Coefficient Power Distribution Classification

A motion picture coding algorithm using motion-compensated interframe prediction and the adaptive discrete cosine transform (DCT) encoding technique is proposed. High coding efficiency is obtained by the adaptive DCT encoding technique in which encoding parameters are fitted to widely varying characteristics of the interframe differential signal. Segmented DCT subblocks of interframe prediction error are classified into categories based on their coefficient power distribution characteristics. The adaptation gain results from using a suitable variable word length code set designated by the above classification for encoding each quantization index of DCT coefficients. In addition, a new coding parameter control method is introduced based on the information rate estimation of the current frame. This classification promotes high stability because good estimation accuracy of bits consumption for each DCT subblock is obtained by utilizing the category indexes. Simulation results show that the proposed algorithm has enough coding efficiency to transmit videoconferencing motion pictures through a 384 kbit/s channel.     

基于NSST-DWT-ICSAPCNN的多模态图像融合算法

为了增加融合图像的信息量,结合非下采样剪切波变换（Non-Subsampled Shearlet Transform, NSST）和离散小波变换（Discrete Wavelet Transform, DWT）的互补优势,提出了改进的多模态图像融合方法。采用NSST对两幅源图像进行多尺度、多方向的分解,得到相应的高频子带和低频子带;利用DWT将低频子带进一步分解为低频能量子带和低频细节子带,并利用最大值选择规则融合能量子带;采用改进连接强度的自适应脉冲耦合神经网络（Improved Connection Strength Adaptive Pulse Coupled Neural Network, ICSAPCNN）分别融合细节子带和高频子带,并对能量子带和细节子带进行DWT逆变换,得到融合的低频子带;采用NSST逆变换重构出细节信息丰富的融合图像。实验证明,提出的算法在主观视觉和客观评价方面均优于其他几种算法,且能同时适用于红外与可见光源图像、医学源图像的融合。     

An efficient coding algorithm for the compression of ECG signals using the wavelet transform

A wavelet-based electrocardiogram (ECG) data compression algorithm is proposed in this paper. The ECG signal is first preprocessed, the discrete wavelet transform (DWT) is then applied to the preprocessed signal. Preprocessing guarantees that the magnitudes of the wavelet coefficients be less than one, and reduces the reconstruction errors near both ends of the compressed signal. The DWT coefficients are divided into three groups, each group is thresholded using a threshold based on a desired energy packing efficiency. A binary significance map is then generated by scanning the wavelet decomposition coefficients and outputting a binary one if the scanned coefficient is significant, and a binary zero if it is insignificant. Compression is achieved by 1) using a variable length code based on run length encoding to compress the significance map and 2) using direct binary representation for representing the significant coefficients. The ability of the coding algorithm to compress ECG signals is investigated, the results were obtained by compressing and decompressing the test signals. The proposed algorithm is compared with direct-based and wavelet-based compression algorithms and showed superior performance. A compression ratio of 24:1 was achieved for MIT-BIH record 117 with a percent root mean square difference as low as 1.08%.     

Low complexity shape-adaptive DCT for coding of arbitrarily shaped image segments

A low complexity shape-adaptive DCT transform algorithm for coding pels in arbitrarily shaped image segments is presented. The proposed algorithm is compared to the well established generalized shape-adaptive transform method introduced by Gilge et al. in terms of transform efficiency and computational complexity. Results obtained under both theoretical and experimental conditions show that the new algorithm achieves a transform efficiency close to that of the Gilge method with considerably reduced computational complexity. The proposed shape-adaptive DCT algorithm was implemented into a standard MPEG-1 coder to provide object or segment based coding of images and video with additional content-based functionality. The extended MPEG-1 object based coding scheme can handle generic input sequences and can readily provide MPEG-1 backward compatibility if no contour data is transmitted for a given video sequence. Results for INTRA coding of images indicate that the algorithm allows efficient coding over a wide range of coding parameters — thus providing means for generic coding of segmented video between very high and very low bit rates. It is further shown that some of the content-based based functionalities currently discussed in MPEG-4 can be provided efficiently using the proposed object based coding scheme.     

A 128 Kb/s Hi-Fi audio codec based on adaptive transform codingwith adaptive block size MDCT

A Hi-Fi audio codec with an improved adaptive transform coding (ATC) algorithm is presented using digital signal processors (DSPs). An audio signal with a 20 kHz bandwidth sampled at 48 kHz is coded at a rate of 128 kb/s. The algorithm utilizes adaptive block size selection, which is effective for preecho suppression. A modified discrete cosine transform (MDCT) with a simple window set is employed to reduce block boundary noise without decreasing the performance of transform coding. In addition, a fast MDCT calculation algorithm, based on a fast Fourier transform, is adopted. Weighted bit allocation is employed to quantize the transformed coefficients. The codec was realized by a multiprocessor system composed of newly developed DSP boards. Subjective tests with the codec show that the coding quality is comparable to that of compact disc signals     

基于能量树编码的小波图像压缩算法

针对小波变换的空间能量聚集特性,提出了一种基于能量树编码的小波图像压缩算法。该算法在离散小波变换的基础上,分别对图像的各高频子带按其局部能量构建分层能量树,利用总能量和各层的能量角等效表示子带的小波系数;根据给定的压缩比,选择合适的代价函数构建最佳能量树,然后对其进行量化和编码,通过自适应的比特率分配实现小波图像压缩。实验结果表明,该算法实现简单,重构图像质量好,与当前多种主流的小波图像压缩算法相比,压缩性能有了明显提高。     

一种基于蚁狮最大熵算法与引导滤波的图像融合算法

传统红外与可见光图像融合算法中易出现目标提取不够充分、细节丢失等问题,导致融合效果不理想,从而无法应用于目标检测、跟踪或识别等领域。因此,该文提出一种基于蚁狮优化算法(ALO)改进的最大香农(Shannon)熵分割法结合引导滤波的红外与可见光图像融合方法。首先,使用蚁狮最大熵分割法(ALO-MES)对红外图像进行目标提取,然后,对红外和可见光图像使用非下采样剪切波变换(NSST),并对获得的低频和高频分量进行引导滤波。由提取的目标图像与增强后的红外和可见光低频分量通过低频融合规则得到低频融合系数,增强后的高频分量通过双通道脉冲发放皮层模型(DCSCM)得到高频融合系数,最后经NSST逆变换得到融合图像。实验结果表明,所提算法能够得到目标明确、背景信息清晰的融合图像。

     

Hyperspectral image compression based on lapped transform and Tucker decomposition

In this paper, we present a hyperspectral image compression system based on the lapped transform and Tucker decomposition (LT-TD). In the proposed method, each band of a hyperspectral image is first decorrelated by a lapped transform. The transformed coefficients of different frequencies are rearranged into three-dimensional (3D) wavelet sub-band structures. The 3D sub-bands are viewed as third-order tensors. Then they are decomposed by Tucker decomposition into a core tensor and three factor matrices. The core tensor preserves most of the energy of the original tensor, and it is encoded using a bit-plane coding algorithm into bit-streams. Comparison experiments have been performed and provided, as well as an analysis regarding the contributing factors for the compression performance, such as the rank of the core tensor and quantization of the factor matrices.     

Shedding light on the future of SP for optical recording

Optical recording has lagged behind magnetic recording in two key areas: writable/erasable/rewritable media and density gains from advanced signal processing. While there are some writable optical-disk products available, their writing capability pales in comparison to magnetic recording. A great deal of research and development in writable/erasable/rewritable optical media continues and we address this in the article. Of particular interest is the use of near-field optical approaches to dramatically increase the storage density in both magnetic and optical recording. To a great extent, this article is about the future of signal processing for optical recording, since advanced signal processing has not been applied to any great extent in optical recording. The intention is twofold: (1) to provide a summary of current and existing optical recording technologies, and (2) to encourage and motivate work in advanced signal processing for these and other optical systems. We begin by summarizing the optical recording and readback processes and then describe writable optical channels and the gains associated with using partial-response coding techniques. We then describe nonbinary recording and the potential gains due to signal processing. The digital versatile disc (DVD), multilayer recording, and holographic recording are also discussed     

人工鱼群算法优化的小波图像融合

针对甲状腺肿瘤的B超、核素图像和颅腔横断面的CT,MRI图像,提出一种使用人工鱼群算法寻优的小波图像融合方法。利用小波变换将源图像进行小波分解,得到源图像的低频部分和高频部分。低频部分的系数使用加权融合算法进行融合,为使融合结果包含足够的信息量,以综合熵作为适应值对低频部分使用人工鱼群算法进行优化,得到融合系数的最优权值。高频部分的系数采用取绝对值最大的融合规则。通过小波逆变换得到融合图像。实验过程中,分别对这两组医学图像进行融合。客观评价参数表明该算法能够得到更优的融合图像。     

A 130 Mb/s compact HDTV codec based on a motion-adaptive DCTalgorithm

The authors describe the principle and implementation of a 130 Mb/s compact HDTV codec based on a motion-adaptive DCT (discrete cosine transform) algorithm. They describe a data compression algorithm using motion-adaptive (motion processing over 5 or 10 frames) intrafield two-dimensional (8×8) DCT coding and block-adaptive quantization with eight modes which is suitable for recording systems. The hardware of the codec using a parallel signal processing architecture and three types of gate-array LSIs is discussed. The picture quality evaluation is considered, and suitable picture quality for distribution use is confirmed     

自适应变换编码的理论研究与硬件实现

本文介绍了一种建立在心理声学基础上的适用于宽频带数字音频信号的数据压缩技术，我们利用计算机对自适应变换编解码法的全过程进行了模拟，并采用Ｍｏｔｏｒｏｌａ公司的数字信号处理芯片ＤＳＰ５６００９作为硬件平台，实现了高质量的音频信号压缩编码，试验结果压缩比达到１／１０以下，而且没有明显的音质衰减。     

A direct computation of DCT coefficients for a signal block takenfrom two adjacent blocks

A direct computational algorithm for obtaining the DCT (discrete cosine transform) coefficients of a signal block taken from two adjacent blocks is proposed. This algorithm reduces the number of both multiplications and additions/subtractions compared to the traditional method, which requires inverse transforms of two received coefficient blocks followed by a forward transform. The proposed algorithm is efficient and useful for speech coding and image processing, especially for real-time applications     

Multichannel ECG data compression by multirate signal processingand transform domain coding techniques

A multilead electrocardiography (ECG) data compression method is presented. First, a linear transform is applied to the standard ECG lead signals, which are highly correlated with each other. In this way a set of uncorrelated transform domain signals is obtained. Then, the resulting transform domain signals are compressed using various coding methods, including multirate signal processing and transform domain coding techniques