一种快速相关预测矢量量化的图像编码算法

矢量量化是近年来图像压缩研究中的重要技术，在该技术中，减小编码运算时间和降低平均编码比特率是当前研究的重要问题，目前，已经提出了许多快速编码算法。为了进一步减少图像矢量量化编码的时间和降低编码比特率，提出了一种超前相关预测与快速搜索相结合的快速矢量量化编码算法。该算法在对当前图像块完成编码后，再根据该图像块与相邻的未编码图像块的相关性来预测相邻块的编码值，如果预测成功，则用低比特率表示编码值；否则用绝对误差不等式删除(AEI)算法来求得高比特率编码值，以减少总编码时间和降低平均比特率。测试结果表明，该算法比传统的穷尽搜索算法的编码速度快，且比特率低，同时对编码质量的影响很小。     

A fast VQ codebook search with initialization and search order

Vector quantization (VQ), a lossy image compression, is widely used for many applications due to its simple architecture, fast decoding ability, and high compression rate. Traditionally, VQ applies the full search algorithm to search for the codeword that best matches each image vector in the encoding procedure. However, matching in this manner consumes a lot of computation time and leads to a heavy burden for the VQ method. Therefore, Torres and Huguet proposed a double test algorithm to improve the matching efficiency. However, their scheme does not include an initiation strategy to choose an initially searched codeword for each image vector, and, as a result, matching efficiency may be affected significantly. To overcome this drawback, we propose an improved double test scheme with a fine initialization as well as a suitable search order. Our experimental results indicate that the computation time of the double test algorithm can be significantly reduced by the proposed method. In addition, the proposed method is more flexible than existing schemes.     

Parallel codebook design for vector quantization on a message passing MIMD architecture

Vector quantization (VQ) is a widely used algorithm in speech and image data compression. One of the problems of the VQ methodology is that it requires large computation time especially for large codebook size. This paper addresses two issues. The first deals with the parallel construction of the VQ codebook which can drastically reduce the training time. A master/worker parallel implementation of a VQ algorithm is proposed. The algorithm is executed on the DM-MIMD Alex AVX-2 machine using a pipeline architecture. The second issue deals with the ability of accurately predicting the machine performance. Using communication and computation models, a comparison between expected and real performance is carried out. Results show that the two models can accurately predict the performance of the machine for image data compression. Analysis of metrics normally used in parallel realization is conducted.     

基于快速相关矢量量化的图象编码算法

图象编码已经成为当今计算机世界的重要问题,而矢量量化（ＶＱ）又是近年来有损图象压缩的一种重要技术,它的优点是比特率低以及解码简单,但是其穷尽搜索编码计算量较大,为了降低编码时间,已经有多种快速算法出现在一些文献中,然而这些算法往往不能进一步降低比特率,为了解决这一问题,因此提出了一种新颖快速相关矢量量化（ＣＶＱ）图象编码算法,该算法对图象块的编码采用对角顺序,即在编码过程中根据当前图象块（ＣＶＱ）     

Fast searching algorithm for vector quantisation based on features of vector and subvector

Vector quantisation (VQ) is an efficient technique for data compression and retrieval. But its encoding requires expensive computation that greatly limits its practical use. A fast algorithm for VQ encoding on the basis of features of vectors and subvectors is presented. Making use of three characteristics of a vector: the sum, the partial sum and the partial variance, a four-step eliminating algorithm is introduced. The proposed algorithm can reject a lot of codewords, while holding the same quality of encoded images as the full search algorithm (FSA). Experimental results show that the proposed algorithm needs only a little computational complexity and distortion calculation against the FSA. Compared with the equal-average equal-variance equal-norm nearest neighbour search algorithm based on the ordered Hadamard transform, the proposed algorithm reduces the number of distortion calculations by 8 to 61%. The average number of operations of the proposed algorithm is ,79% of that of Zhibin?s method for all test images. The proposed algorithm outperforms most of existing algorithms.     

一种改进的AEI算法中初始匹配码字的快速查找方法

矢量量化（VQ）是一种高效的有损压缩技术。快速码字搜索算法是矢量量化的核心问题之一,其性能决定了编码时间。快速码字搜索算法中,绝对误差不等式删除算法(AEI)是一种典型的3步算法,其第1步查找输入矢量的初始匹配码字的方法采用了Minimax法,是整个AEI算法中计算量最大的步骤,严重影响了算法的效率。针对这个问题,提出了一种新的查找初始匹配码字的方法——Partial Minimax法。该方法在保证所找到的初始匹配码字与原始AEI算法相同并且重建图像的PSNR（峰值信噪比）值不变的前提下,可显著减小这一步骤的计算量和查找时间,从而有效地提高了算法的总体编码速度。     

均值与矢量量化复合快速图像编码算法

矢量量化是一种有效的数据压缩技术,由于其算法简单,具有较高的压缩率,因而被广泛应用于数据压缩编码领域。通过对图像块灰度特征的研究,根据图像的平滑与否,提出了对图像进行均值和矢量量化复合编码算法,该算法对平滑图像块采用均值编码,对非平滑块采用矢量量化编码。这不仅节省了平滑码字的存储空间,提高了码书存储效率,并且编码速度大大提高。同时采用码字旋转反色（2R）压缩算法将码书的存储容量减少到1/8,并结合最近邻块扩展搜索算法（EBNNS）对搜索算法进行优化。在保证图像画质的前提下,整个系统的图像编码速度比全搜索的普通矢量量化平均提高约7.7倍。     

基于自组织特征映射神经网络的矢量量化

近年来,许多学者已经成功地将Ｋｏｈｏｎｅｎ的自组织特征映射（ＳＯＦＭ）神经网络应用于矢量量化（ＶＱ）图象压缩编码,相对于传统的ＫＬＢＧ算法,基于的ＳＯＦＭ算法的两个主要缺点是计算量大和生成的码书性能较差因此为了改善码书性能,对基本的ＳＯＦＭ算法的权值调整方法作了一些改进,同时为了降低计算量,又在决定获得胜神经元的过程中,采用快速搜索算法,在将改进的算法用于矢量量化码书设计后,并把生成的码书用于图象     

An improved search algorithm for vector quantization using mean pyramid structure

Vector quantization (VQ) is a well-known data compression technique. In the codebook design phase as well as the encoding phase, given a block represented as a vector, searching the closest codeword in the codebook is a time-consuming task. Based on the mean pyramid structure and the range search approach, an improved search algorithm for VQ is presented in this paper. Conceptually, the proposed algorithm has the bandpass filter effect. Each time, using the derived formula, the search range becomes narrower due to the elimination of some portion of the previous search range. This reduces search times and improves the previous result by Lee and Chen (A fast search algorithm for vector quantization using mean pyramids of codewords. IEEE Trans. Commun. 43(2/3/4), (1995) 1697–1702). Some experimental results demonstrate the computational advantage of the proposed algorithm.     

一种快速的矢量量化编码

研究了一种基于均方误差（MSE）测度的矢量量化快速编码算法。算法利用小波变换的特点,合理地构造矢量,便于非线性插补矢量量化技术的使用,也使部分失真排除法的效率大大提高。使用矢量的二范数和距离测度关系的码字排除方法,再结合非线性插补矢量量化技术和部分失真排除法,在搜索编码过程中,有效排除部分候选码字。实验结果表明,相对于穷尽搜索方法,计算量有明显降低,计算时间显著减少。     

Boundary correlation-based intracoding for SHVC algorithm and its efficient VLSI architecture

Scalable high-efficiency video coding (SHVC) can provide variable video quality according to terminal devices. However, a computational complexity of SHVC is increased by introducing new techniques based on high-efficiency video coding (HEVC). In this paper, a hardware-oriented low complexity algorithm is proposed for the reference software of SHVC (SHM11.0). In our proposed algorithm, an optimal coding unit depth is determined by analyzing the boundary correlation in a coding tree unit before encoding starts. Simulation results show that the proposed algorithm can achieve over 62% computation complexity reduction comparing to the original SHM11.0. Compared with other related work, over 11% time saving has been achieved without PSNR loss. Moreover, to confirm the efficacy of the proposed algorithm, a hardware architecture is designed targeting on the CU depth decision algorithm. Synthesis results show that the hardware cost is about 1.8K gate and achieve a scalable working clock frequency in the case of FPGA (CycloneV) implementation.     

Novel full-search schemes for speeding up image coding using vector quantization

The routine for finding the closest codeword in the encoding phase of vector quantization (VQ) is high computational complexity and time consuming, especially when the codewords deal with the high-dimensional vectors. In this paper, we propose three newly developed schemes for speeding up the encoding phase of VQ. The proposed schemes can easily filter out many impossible codewords such that the search domain is reduced. The experimental results show that the computational time of our proposed schemes can save more than 41–52% computational time in a full search scheme. Furthermore, our schemes only require fewer than 84% of the computational time required in recently proposed alternative.     

归一化积相关算法加速方法研究及FPGA实现

随着飞航导弹向高效打击和提升智能的方向发展,为了保证打击的精确性,对地形匹配、目标识别的实时性要求也越来越高,单靠DSP软件进行图像处理的做法已经难以满足要求。根据FPGA实现数学运算的特点,提出了归一化积相关算法公式的化简方法,具有精度高、速度快的特点,并设计了积相关硬件加速电路单元架构和积相关多路并行计算架构,通过在FPGA上进行实现验证,能够满足新一代飞航导弹地形匹配及目标识别的实时性要求。     

A new area-efficient BCD-digit multiplier

In the Internet of Things era, with millions of devices performing financial and commercial operations, decimal arithmetic has become very popular in the computation of many business and commercial applications, in order to maintain decimal rounding and precision. This paper proposes the design and implementation of a new algorithm for decimal multiplication oriented to area reduction. This algorithm is especially suitable for field programmable gate arrays (FPGA) and has thus been implemented on this kind of devices. Results show that the proposed BCD multiplication leads to a significant area reduction without decreasing system performance.     

改进的矢量量化码字快速搜索法

矢量量化技术是一种高效和有竞争力的数据压缩方法,但由于其编解码过程中需要较大的计算量影响了其使用。提出了一种改进的基于子矢量特征值的码字快速搜索算法。算法充分利用矢量的3个特征值即和值、子矢量和值以及方差,建立起一种5步码字排除法,使得算法能够快速排除大部分不匹配码字,实现减少计算量的目的。仿真实验结果表明,算法的计算量要小于ZhiBin算法、Pan算法以及Chen算法,证明了改进算法的有效性。     

一种基于积分投影的矢量量化器的设计与实现

提出了一种积分投影和矢量量化（VQ）相结合的图像压缩算法,将图像的每一个4×4分块先进行积分投影,然后再与积分投影后的码书进行量化匹配,大大减少运算量和码书存储面积,而图像的质量只有轻微损失。实验结果表明,与普通VQ相比,本文算法的编码速度有很大幅度的提高,而解码图像的峰值信噪比（PSNR）平均仅降低0.25%,对于某些单纯背景的图像,解码后的质量比普通VQ还会有所增加,此算法有很大的应用前景。设计了编码电路,并在FPGA上进行了验证。整个系统最高时钟频率可达78.12 MHz。     

A fast vector quantization encoding algorithm based on projection pyramid with Hadamard transformation

Vector quantization (VQ) for image compression requires expensive time to find the closest codevector in the encoding process. In this paper, a fast search algorithm is proposed for projection pyramid vector quantization using a lighter modified distortion with Hadamard transform of the vector. The algorithm uses projection pyramids of the vectors and codevectors after applying Hadamard transform and one elimination criterion based on deviation characteristic values in the Hadamard transform domain to eliminate unlikely codevectors. Experimental results are presented on image block data. These results confirm the effectiveness of the proposed algorithm with the same quality of the image as the full search algorithm.     

Vector-quantization-based video codec for software-only playback on personal computers

This paper discusses a video compression and decompression method based on vector quantization (VQ) for use on general purpose computer systems without specialized hardware. After describing basic VQ coding, we survey common VQ variations and discuss their impediments in light of the target application. We discuss how the proposed video codec was designed to reduce computational complexity in every principal task of the video codec process. We propose a classified VQ scheme that satisfies the data rate, image quality, decoding speed, and encoding speed objectives for software-only video playback. The functional components of the proposed VQ method are covered in detail. The method employs a pseudo-YUV color space and criteria to detect temporal redundancy and low spatial frequency regions. A treestructured-codebook generation algorithm is proposed to reduce encoding execution time while preserving image quality. Two separate vector codebooks, each generated with the treestructured search, are employed for detail and low spatial frequency blocks. Codebook updating and sharing are proposed to further improve encoder speed and compression.     

基于矢量量化的数字视频压缩技术

对基于矢量量化的数字视频压缩技术进行了论述，并根据分析结果提出了一种新的矢量量化算法——多级矢量量化联合编码算法，该算法保持了多级矢量量化算法编码速度快、图像相关性小等特点，同时提高了编码质量。实验表明，该算法与已有的算法相比具有较高的图像质量和更高的压缩率。     

蚁群算法硬件实现的研究进展

蚁群算法是优化领域中新出现的一种启发式仿生类智能进化算法，该算法采用分布式并行计算和正反馈机制．首先综述了蚁群算法及其硬件实现的研究进展，并讨论了蚁群算法硬件的主要特点；然后，着重介绍了基于现场可编程门阵列（FPGA）的蚁群算法硬件实现方案，简要阐述了蚁群算法在软硬件划分领域的应用进展；最后，展望了蚁群算法硬件实现领域未来的研究方向和内容．