用TMS320C25实现图像的（8＊8）离散余弦变换

本文研究了图像的（８×８）像素ＤＣＴ快速产现的基本方法，分析了直接（８×８）２－ＤＤＣＴ和８点１－ＤＤＣＴ实现（８×８）２－ＤＤＣＴ的两步算法的两种矩阵分解模型，并对这两种实现方法进行了比较，在比较的基础上选用两步快速算法实现图像ＤＣＴ。在硬件实现中，研究了ＤＳＰ芯片ＴＭＳ３２０Ｃ２５的特点，提出了软件设计的准则和技巧，确定了硬件配置。通过上机与实验测试，取得的结果是：使用一片ＴＭＳ３２０Ｃ２５，     

静像数据压缩及其标准JPEG（下）

静像数据压缩及其标准ＪＰＥＧ（下）曾国良，丁宗豪七、离散余弦变换ＤＣＴ图２中方框５的作用是将“二维”空间的图像数据用离散余弦变换ＤＣＴ公式变换到二维频域成为二维频率系数。在叙述二维ＤＣＴ公式以前，在此补充一些基本知识。我们知道离散傅氏变换ＤＦＴ及其快...     

图像编码的平面逼近法及其应用

本文提出了一种采用平面逼近的图像编码方法。将图像方块中的象素,用一最佳平面上的相应点代替,从而只需对平面方程的三个参数进行编码,理论分析和实验结果证明,该方法适合对图像中灰度变化缓慢的区域的编码。当与ＤＣＴ方法结合时,能够有效地消除ＤＣＴ方法在低码率时的方块效应。     

DC3T的若干性质

本文证明了一种非正交离散余弦变换－ＤＣ３Ｔ具有与经典ＤＣＴ相同的残余相关和更高的变换编码增益，分析了它的熵压缩和能量压缩性质，给出计算复杂度和递推算法，结果表明ＤＣ３Ｔ比ＤＣＴ更适合于图像数据压缩。     

雷达图像压缩

本文提出了一种建立在数字压缩技术基础上的算法，它适合于ＶＴＳ（ＶｅｓｓｅｌＴｒａｆｆｉｃｅＳｅｒｖｉｃｅ）船舶航行管理）系统的雷达数据，基本思想来源于ＪＰＥＧ（ＪｏｉｎｔＰｈｏｔｏｇｒａｐｈｉｃＥｘｐｅｒｔｓＧｒｏｕｐ）标准，该标准通过使用２－Ｄ离散余弦变换（ＤＣＴ）把图像数据转换为一个立体频率，将这些成份量化成不同的离散度，以反央人的视觉系统的立体频率灵敏度，然后使用变长编码对其编码。此算法已被     

HDTV的帧内子带编码

本文提出了一种将ＨＤＴＶ信号的传输码率由１．２Ｇｂ／ｓ压缩至１４０Ｍｂ／ｓ以下的帧内子带ＤＣＴ编码方案，所提出的缓存器分级自适应控制方法可更有效地均衡码流。计算机模拟结果表明，ＨＤＴＶ图像数据压缩至１２０Ｍｂ／ｓ以下时，仍可达到传输质量要求。由于只采用了帧内编码方式，所以设备比较简单。     

一种基于自组织神经网络的图像压缩编码算法

本文提出了一种基于自组织特征映射神经网络的图像压缩编码算法，即ＶＱ＋ＤＰＣＭ＋ＤＣＴ算法，实验表明，在压缩比为３１．８∶１时，其峰峰信噪比为３５．８２ｄＢ（Ｌｅｎｎａ亮度图像），且主观效果良好，这是至今为止使用矢量量化（ＶＱ）方法压缩图像所获得的最好结果。     

基于非负矩阵分解的谱聚类集成SAR图像分割

 本文提出了一种新颖的基于非负矩阵分解的谱聚类集成SAR图像分割框架.首先,个体分割结果的产生采用基于Nystrom逼近的谱聚类方法,使用不同的尺度参数,得到具有差异性的个体分割结果;其次,使用非负矩阵分解的方法来合并这些个体分割结果,使用非负矩阵分解方法的优点在于其合乎人类大脑感知的直观体验,并具有明确的物理含义;最后,根据合并得到的像素点隶属度关系得到SAR图像分割结果.为了验证本文方法的有效性,对3幅纹理图像和4幅SAR图像进行分割实验,并对比K-means方法、基于Nystrom逼近的谱聚类方法、Meta-clustering方法,本文的方法无论是定性还是定量分析都是较好的,并具有一定的实用性.     

复杂背景下基于分割逼近法的抠像技术研究

论述了复杂背景下人物的抠像问题,提出一种新的抠像方法--分割逼近算法.首先使用背景更新模型建立了差分背景,然后用本文提出的分割逼近法对图像进行粗分和细分两次分割,建立了人物图像边缘连通体,最后运用Laplacian算子对勾勒出的人物轮廓提取边缘,并用替换原图像的方法实现人物的抠像.     

一种计算机快速二维DCT算法

二维离散余弦变换（２Ｄ－ＤＣＴ）广泛用于数字图像处理中，特别是图像的数据压缩，二维ＤＣＴ的常规算法是行一列法，对于计算（Ｎ×Ｎ）ＤＣＴ，需要计算２Ｎ个一维ＤＣＴ。本文利用三角函数的公式，并将二维输入数据划分为Ｎ个不同的数据集，提出了一种快速算法。该算法对于计算（Ｎ×Ｎ）ＤＣＴ只需要计算Ｎ个一维ＤＣＴ，运算量是常规算法的一半。该算法的计算结构具有高度规则性，只要求执行实数运算。     

模型优化及其在DT模型基图像编码中的应用

本文提出一种新的近似模型ＤＴ网格动态优化方法，作为二维ＤＴ模型基图像编码方法的改进型方案。优化过程维持了ＤＴ网格的优良特性，从而在提高编译码效率和恢复图像质量方面比其它类型的网格更有优势。近似模型的优化使恢复图像的主客观质量显著提高，从而使整个方案在相同信噪比条件下具有更高的数据压缩比。最后给出新方案的实验结果来说明其性能     

Fractal image compression based on Delaunay triangulation andvector quantization

Presents a new scheme for fractal image compression based on adaptive Delaunay triangulation. Such a partition is computed on an initial set of points obtained with a split and merge algorithm in a grey level dependent way. The triangulation is thus fully flexible and returns a limited number of blocks allowing good compression ratios. Moreover, a second original approach is the integration of a classification step based on a modified version of the Lloyd algorithm (vector quantization) in order to reduce the encoding complexity. The vector quantization algorithm is implemented on pixel histograms directly generated from the triangulation. The aim is to reduce the number of comparisons between the two sets of blocks involved in fractal image compression by keeping only the best representative triangles in the domain blocks set. Quality coding results are achieved at rates between 0.25-0.5 b/pixel depending on the nature of the original image and on the number of triangles retained.     

基于Delaunay三角形网格的彩色视频帧间编码方法

充分利用彩色视频亮度和色度分量之间的相关性,提出了一种基于DT网格的彩色视频帧间编码方案。该方案在运动估计时仅对亮度分量Y进行DT(Delaunay triangulation)描述,对亮度分量的网格节点进行连续运动估计,利用6参数方法得到三角形内像素点的运动矢量,经过相似变换得到色度分量的运动矢量。另外对残差图像进行特殊处理和编码。实验结果表明,相对于适合低码率传输的H.263编码方法,在相同的压缩比下该方案解码图像有更好的主客观质量。     

A new LBG-based image compression method using DCT

In this letter, a new Linde-Buzo-Gray （LBG）-based image compression method using Discrete Cosine Transform （DCT） and Vector Quantization （VQ） is proposed. A gray-level image is firstly decomposed into blocks, then each block is subsequently encoded by a 2D DCT coding scheme. The dimension of vectors as the input of a generalized VQ scheme is reduced. The time of encoding by a generalized VQ is reduced with the introduction of DCT process. The experimental results demonstrate the efficiency of the proposed method.     

摄像机标定中特征点的一种自动对应方法

基于计算几何理论中Delaunay三角化原理,提出了一种对具有阵列网络结构的靶标特征点的图像坐标与世界坐标进行自动对应方法.通过对图像处理获取的特征点进行Delaunay三角化预处理,并去除冗余三角形,得到相邻特征点之间的几何连接关系,利用特征点之间的连接关系实现阵列网络结构的靶标特征点的图像坐标与世界坐标的对应.实验...     

Compression of image block means for non-equal block partition schemes using Delaunay triangulation and prediction

An approach based on applying Delaunay triangulation to the compression of mean values of image blocks that have non-identical shape and size is proposed. It can be useful for image compression methods that require the use of image partition schemes with non-equal block sizes, such as fractal and DCT-based image coding. Some aspects of practical realisation of the proposed method are discussed. Evaluation of the performance of the proposed method is carried out and comparisons with some conventional methods are made, demonstrating the potential of the method.     

High resolution image formation from low resolution frames using Delaunay triangulation

An algorithm based on spatial tessellation and approximation of each triangle patch in the Delaunay (1934) triangulation (with smoothness constraints) by a bivariate polynomial is advanced to construct a high resolution (HR) high quality image from a set of low resolution (LR) frames. The high resolution algorithm is accompanied by a site-insertion algorithm for update of the initial HR image with the availability of more LR frames till the desired image quality is attained. This algorithm, followed by post filtering, is suitable for real-time image sequence processing because of the fast expected (average) time construction of Delaunay triangulation and the local update feature.     

基于多线性子空间KL变换的可伸缩视频压缩方法

该文提出一种基于多线性子空间KL(Karhunen-Loeve)变换的可伸缩视频压缩算法。该算法将纹理不同的图像子块投影到多个线性子空间中去,然后分别进行KL变换编码,使得每个子空间内变换系数更接近高斯分布,从而最大限度地在变换编码阶段提高压缩效率。同时,该算法结合多尺度小波分解,实现了质量可伸缩的视频编码,提高了视频压缩率。通过与DCT、小波变换以及多向DCT算法进行比较,证明该算法可获得更好的率失真性能。     

Progressive Image Transmission Using LOT with Two-Channel Conjugate VQ

A progressive image transmission (PIT) scheme based on the classified two-channel conjugate VQ (TCCVQ) technique in the lapped orthogonal transform (LOT) domain is proposed. Conventional block transform coding of images using DCT produces in general undesirable block-artifacts at low bit rates. In this paper, image blocks are transformed using the LOT and classified into four classes based on their structural properties and further subdivided adaptively into subvectors depending on the LOT coefficient statistics to improve the reconstructed image quality by adaptive bit allocation. The subvectors are quantized using the two-channel conjugate VQ technique which has less computational complexity and less storage memory, and is more robust against channel errors. The vector quantized subvectors are transmitted and decoded in stages so that an image is progressively reconstructed, i.e., initially a crude version followed by quality build up in successive stages as the occasion demands in interactive visual communications. Coding tests using computer simulations show that the LOT/TCCVQ-based PIT of images is an effective coding scheme. The results are also compared with those obtained using conventional classified VQ in both the DCT and LOT domains.     

Edge-based motion compensated classified DCT with quadtree for image sequence coding

The motion compensated discrete cosine transform coding (MCDCT) is an efficient image sequence coding technique. In order to further reduce the bit-rate for the quantizied DCT coefficients and keep the visual quality, we propose an adaptive edge-based quadtree motion compensated discrete cosine transform coding (EQDCT). In our proposed algorithm, the overhead moving information is encoded by a quadtree structure and the nonedge blocks will be encoded at lower bit-rate but the edge blocks will be encoded at higher bit-rate. The edge blocks will be further classified into four different classes according to the orientations and locations of the edges. Each class of edge blocks selects the different set of the DCT coefficients to be encoded. By this method, we can just preserve and encode a few DCT coefficients, but still maintain the visual quality of the images. In the proposed EQDCT image sequence coding scheme, the average bit-rate of each frame is reduced to 0.072 bit/pixel and the average PSNR value is 32.11 dB.