一种基于提升的二维离散小波变换VLSI架构

离散小波变换(Discrete Wavelet Transform,DWT)需要较多的运算量以及较大的存储器空间,为了使之适用于实时的图像处理应用,就需要开发特殊的架构和芯片来提高离散小波变换的运算性能。基于提升的二维DWT提出了一种新型的VLSI结构——LLSP架构,其结合逐级和基于行的架构这两者特点,带来了硬件开销和存储器空间的降低,并可以用于多提升步骤的扩展以及多级二维离散小波变换。     

DWT based HMM for face recognition

A novel Discrete Wavelet Transform (DWT) based Hidden Markov Module (HMM) for face recognition is presented in this letter. To improve the accuracy of HMM based face recognition algorithm, DWT is used to replace Discrete Cosine Transform (DCT) for observation sequence ex- traction. Extensive experiments are conducted on two public databases and the results show that the proposed method can improve the accuracy significantly, especially when the face database is large and only few training images are available.     

一种快速高效的二维一级小波变换的硬件实现

提出了一种针对9/7小波滤波器的二维一级小波变换的硬件平台,整体结构采用流水方式实现,数据分组输入,列变换采用多个小波变换单元,行变换模块为可重构硬件结构,行列变换之间不需要片上存储器。与已有结构相比,该结构可以通过更少的硬件资源消耗获得更高的处理速度。     

Memory-efficient high-speed VLSI implementation of multi-level discrete wavelet transform

Memory requirements and critical path are essential for 2-D Discrete Wavelet Transform (DWT). In this paper, we address this problem and develop a memory-efficient high-speed architecture for multi-level two-dimensional DWT. First, dual data scanning technique is first adopted in 2-D 9/7 DWT processing unit to perform lifting operations, which doubles the throughputs per cycle. Second, for 2-D DWT architecture, the proposed Row Transform Unit and Column Transform Unit take advantage of input sample availabilities and provision computing resources accordingly to optimize the processing speed, in which the number of processors is further optimized to significantly reduce the hardware cost. Third, to address the problem of high cost of memory for the immediate computing results from each level and the computation time as resolution level increases, multiple proposed 2-D DWT units were combined to build a parallel multi-level architecture, which can perform up to six levels of 2-D DWT in a resolution level parallel way on any arbitrary image size at competitive hardware cost. Experimental results demonstrated that the proposed scheme achieves improved hardware performance with significantly reduced on-chip memory resource and computational time, which outperforms the-state-of-the-art schemes and makes it desirable in memory-constrained real-time application systems.     

A Parallel-Based Lifting Algorithm and VLSI architecture for DWT

A novel Parallel-Based Lifting Algorithm （PBLA） for Discrete Wavelet Transform （DWT）, exploiting the parallelism of arithmetic operations in all lifting steps, is proposed in this paper. It leads to reduce the critical path latency of computation, and to reduce the complexity of hardware implementation as well. The detailed derivation on the proposed algorithm, as well as the resulting Very Large Scale Integration （VLSI） architecture, is introduced, taking the 9/7 DWT as an example but without loss of generality. In comparison with the Conventional Lifting Algorithm Based Implementation （CLABI）, the critical path latency of the proposed architecture is reduced by more than half from （4Tm ＋ 8Ta）to Tm ＋ 4Ta, and is competitive to that of Convolution-Based Implementation （CBI）, but the new implementation will save significantly in hardware. The experimental results demonstrate that the proposed architecture has good performance in both increasing working frequency and reducing area.     

一种基于小波变换与奇异分解的图像水印算法

提出一种基于离散小波变换(Discrete Wavelet Transform,DWT)与奇异值分解(Singular Value Decomposition,SVD)相结合的数字水印算法。该算法将原始图像的小波子图进行奇异值分解,将灰度水印图像进行Arnold变换以及扰乱加密,再进行分块离散余弦变换(Discrete Cosine Transform,DCT),将变换后的系数分类嵌入到相应的奇异值中。实验仿真表明,这种方法能抗大多数图像处理攻击,具有良好的鲁棒性。     

双树复小波变换及其应用综述

双树复小波变换是为克服通常的离散小波变换的缺陷而提出的。当对应小波基（近似）满足Hilbert变换关系时，双树复小波变换能够极大地减小通常的实小波变换中的平移敏感性，改善方向选择性。这些优点使双树复小波变换成为有效的图像配准融合工具，能够显著提高配准融合质量。     

A Unified FPGA-Based System Architecture for 2-D Discrete Wavelet Transform

This paper presents a novel unified and programmable 2-D Discrete Wavelet Transform (DWT) system architecture, which was implemented using a Field Programmable Gate Array (FPGA)-based Nios II soft-core processor working in combination with custom hardware accelerators generated through high-level synthesis. The proposed system architecture, synthesized on an Altera DE3 Stratix III FPGA board, was developed through an iterative design space exploration methodology using Altera’s C2H compiler. Experimental results show that the proposed system architecture is capable of real-time video processing performance for grayscale image resolutions of up to 1920?×?1080 (1080p) when ran on the Altera DE3 board, and it outperforms the existing 2-D DWT architecture implementations known in literature by a considerable margin in terms of throughput. While the proposed 2-D DWT system architecture satisfies real-time performance constraints, it can also perform both forward and inverse DWT, support a number of popular DWT filters used for image and video compression and provide architecture programmability in terms of number of levels of decomposition as well as image width and height. Based from the design principles used to implement the proposed 2-D DWT system architecture, a system design guideline can be formulated for SOC designs which plan to incorporate dedicated 2-D DWT hardware acceleration.     

基于小波变换的数字水印应用

伴随着网络技术扣多媒体技术的飞速发展，数字媒体给人们带来极大便利的同时，也面临着严峻的挑战，版权保护扣信息安全成为一个迫在眉睫的现实问题。数字水印技术作为版权保护扣信息安全的重要手段得到了广泛的研究扣应用，他通过在原始数据中嵌入秘密信息——水印来证实该数据的所有权或完整性，达到版权保护扣信息安全的目的．本文基于人类视觉系统(HVS)的特性，提出了一种小波变换域的数字水印算法，将水印图像嵌入到小波变换的不同方位的重要系数当中，文中实现了标志图像水印．实验结果表明，该水印算法对图像处理扣压缩等运算有较强的鲁棒性。     

小波图像编码的硬件实现

设计了二维离散小波变换和快速零树编码的硬件结构,实现了一小波图像编码系统.编写了各个模块的Verilog HDL模型,并进行了仿真和逻辑综合.最后用Altera公司的CPLD对整个编码系统进行了验证.结果表明,设计的硬件结构是正确的,可以用来实现小波图像编码系统.     

Comment on “Robust blind image watermarking scheme based on Redundant Discrete Wavelet Transform and Singular Value Decomposition”

It is shown that the robust blind image watermarking scheme based on Redundant Discrete Wavelet Transform and Singular Value Decomposition proposed by Makbol and Khoo in this AEÜ journal has a fundamental flaw in its design that undermines the security of its scheme against the false-positive problem. More crucially, this result therefore invalidates the objective of the scheme that is to achieve ownership protection, so the scheme cannot be used. In more detail, an adversary is able to claim ownership of a watermarked image by extracting his watermark from the image, although his watermark has never been inserted into the image in the first place. We then verified the flaw through experimental results and thus, proved that the Makbol and Khoo scheme was not able to solve the false-positive problem as claimed and should not be used for proof of ownership applications. In discussing ways to mitigate the problem, we investigate an approach that would have worked quite efficiently if Discrete Wavelet Transform was used instead of Redundant Discrete Wavelet Transform.     

Fast text location based on discrete wavelet transform

The paper describes a texture-based fast text location scheme which operates directly in the Discrete Wavelet Transform (DWT) domain. By the distinguishing texture characteristics encoded in wavelet transform domain, the text is fast detected from complex background images stored in the compressed format such as JPEG2000 without full decompress. Compared with some traditional character location methods, the proposed scheme has the advantages of low computational cost, robust to size and font of characters and high accuracy. Preliminary experimental results show that the proposed scheme is efficient and effective.     

压缩感知重构算法在“鬼”成像中的应用研究

“鬼”成像（GI）提供了一种用常规手段很难达到的特殊的获取图像方法,在量子光学领域是近些年来的前沿和热点之一。本文中,主要研究压缩感知（CS）的重构算法在“鬼”成像中的应用。我们使用具有高斯分布的热光源强度分布,来作为压缩感知的测量矩阵,分别以离散余弦变换(DCT)和离散小波变换(DWT)作为压缩感知中图像物体的稀疏矩阵,利用正交匹配追踪算法,最终获得基于压缩感知重构算法的“鬼”成像。研究结果表明,压缩比为0.5时,基于离散余弦变换基的压缩“鬼”成像（DCT-CS）和基于小波变换基的压缩“鬼”成像(DWT-CS),比“鬼”成像原始重建算法有超过10dB的峰值信噪比提升;同时,基于DCT-CS算法的重建质量要优于DWT-CS算法。      

提升格式的小波变换及在视频压缩中的应用

提升方法是计算离散小波变换的有效手段，将提升三维小波变换用于视频信号压缩。时间方向小渡变换选用Haar滤波器组，空间小波变换则在常规的图像编码所常用的D9/7滤波器组基础上，对其参数进行调整，进一步减少运算量。实验表明这种调整取得了与D9/7双正交小波基本一致图像编码效果，但提高了运算速度。     

Efficient FPGA architecture of optimized Haar wavelet transform for image and video processing applications

Multidimensional Systems and Signal Processing - Discrete Wavelet Transform (DWT) is widely used in digital image and video processing due to its various advantages over other similar transform...     

JPEG2000小波变换器的VLSI结构设计

新一代静止图像压缩标准JPEG2000将离散小波变换(DWT)作为其核心变换技术,并推荐采用推举体制(lifting)快速算法来实现.空间组合推举体制算法(SCLA)大大降低了lifting的运算量.当选用9/7小波滤波器时,SCLA的乘法运算量只有lifting的7/12.本文提出了一种实现SCLA算法的VLSI结构,降低了基于lifting实现的运算量, 加快了变换的速度,减小了电路的规模.本文的二维正反小波变换器已经作为单独的IP核应用于我们目前正在开发的JPEG2000图像编解码芯片中.     

JPEG2000小波提升算法的硬件设计

离散小波变换是当今许多图像处理和压缩技术的基础,并被最新的ISO/IEC静态图像压缩标准JPEG2000所采用.基于提升方法的离散小波变换比传统的基于卷积的运算量小.我们为JPEG2000中的小波提升算法提出一个硬件结构,该结构整体运算速度高,存储需求低,硬件资源耗费少.我们提出在数据通道之外实现边界扩展,以降低数据通道的复杂性,提高运算效率.我们通过采用流水线技术,进一步提高了硬件设计的运算效率.     

一种基于DWT的同步数字音频水印算法

本文提出了一种基于离散小波变换的同步数字音频盲水印算法。嵌入的水印为视觉上可辨的二值图像。算法中引入了嵌入同步信号的思想,利用同步信号定位水印的嵌入位置。为了提高信号的鲁棒性,把同步信号与水印隐藏在DWT域的低频系数中。同时,检测水印时不需要原始音频。仿真实验表明,所提出的方法具有较强的鲁棒性和不可感知性,并能有效抵御各种常见攻击。     

基于整数小波变换和改进嵌入零树编码的图像压缩

整数小波变换(IWT)具有输入输出都是整数、只需进行位内运算、便于硬件实现等优点,特别适于图像的无损压缩;而在有损压缩方面,其效果通常稍逊于传统的离散小波变换(DWT)。为了提高IWT图像有损压缩的性能,该文采用基于提升格式的IWT,结合基于形态膨胀运算的改进嵌入零树小波编码(EZW)方法。实验结果表明,在没有增加运算复杂度的情况下,此算法与传统的DWT相比,提高了峰值信噪比(PSNR),具有较好的有损压缩效果。