Description: 本文结合DCT变换的特性，利用分形的Peano一hilbert扫描曲线，对基于DCT变换的图像编码方法进行了研究，并提出了改进方法。主要工作分为两个部分: 一是在分块DCT基础上的改进。对分块后生成的各图像块矩阵，不直接作二维DCT变换，而是先进行扫描，使之重排成一维向量，再进行一维DCT变换，这样可以减少运算量。 其次是对层次余弦变换编码部分的改进。使用层次DCT变换与零树编码相结合的方法，并在扫描编码过程中，按Peano一hilbert扫描顺序进行编码。这样不仅可以减少“块效应”，而且可以加快编码速度。-this paper the characteristics of DCT, using fractal Peano a Hilbert scanning curve, the DCT-based image coding method for the study and improvement of methods. The work is divided into two main parts : First, the DCT block on the basis of improvements. Right after block production of the image block matrix, not for direct two-dimensional DCT, but first scan, so they line up in a heavy-dimensional vector and then a peacekeeping DCT, thus reducing the amount of computation. Secondly, the level of cosine transform coding some of the improvements. The use level of DCT and zero tree coding combination of methods, coding and scanning process, according to a Hilbert Peano code scanning sequence. This will not only reduce the "blocking effect" but we can speed up the coding speed. Platform: |
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Author:lzy |
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Description: 数字图像处理实验
根据原图像的直方图，发现背景和目标的分割值大约在130左右，并将灰度图像转为二值图像，分割效果比较理想。
图像处理实验（六）图像压缩与编码
实验目的： 学习JPEG压缩编码
实验内容：
一．实现基本JPEG的压缩和编码分三个步骤：
1． 首先通过DCT变换去除数据冗余；
2． 使用量化表对DCT系数进行量化；
3． 对量化后的系数进行Huffman编码。-digital image processing experiments based on the original image histogram, found background and objectives of the divided about the value of around 130 and two gray-scale image to image, Segmentation more satisfactory results. Image processing experiments (6) Image Compression and Coding of the experiment : Learning JPEG compression coding experiment : one. Basically JPEG compression and coding in three steps : 1. First through DCT remove data redundancy; 2. Using quantitative table right DCT coefficient quantization; 3. Right quantized coefficients of Huffman coding. Platform: |
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Author:qq |
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Description: dct and idct for image.matlab实现信息序列的嵌入和提取-dct and idct for image.matlab realize embedded information and extract sequence Platform: |
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Author:wubaishan |
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Description: 使用二维离散余弦变换(DCT)进行图象压缩。原始图象被转换成为8*8大小的块进行压缩和重构。 Cnum:为压缩时保留的系数的个数 MSM:均方误差压缩应该做到在最合理的近似原图象的情况下使用最少的系数。函数：dctmtx:返回一个n*n阶DCT变换 blkproc:对图象进行不同的块处理。 im2col:重排图象块为矩阵列。注意：只适用于灰度图象。-The use of two-dimensional discrete cosine transform (DCT) for image compression. Original image is converted to become the size of 8* 8 block compression and reconstruction. Cnum: reservations for the compression factor of the number of MSM: mean square error compression should be done in the most reasonable approximation of the original image using the least coefficient. Function: dctmtx: returns an n* n-order DCT transform blkproc: image processing of different blocks. im2col: rearrangement of the matrix block out images. Note: only applicable to grayscale images. Platform: |
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Author:hff |
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Description: 使用DCT算法实现8X8的BMP图像压缩的一个源代码，希望对大家有用~-8x8 algorithm using DCT image compression of BMP, a source code, in the hope that useful to everyone ~ Platform: |
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Author:viconia |
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Description: dctcom.m文件利用DCT变换完成对输入图像进行压缩；imagecbe.m完成对输入的两幅RGB图像用小波分析的方法进行图像融合 imagecom.m完成对输入的RGB图像用小波分析的方法进行自动降噪，得到高频系数阈值，降噪效果百分比和结果 wavelet1D.m完成对输入的一维信号进行多尺度离散小波分解 wavelet2D完成对输入的二维信号进行多尺度离散小波分解；zigzag.m完成对输入的8*8矩阵按照zigzag排列抽取数据.-document the use of DCT transform dctcom.m completion of the input image compression imagecbe.m completion of the two RGB input image with wavelet analysis method of image fusion imagecom.m completion of the input RGB image using wavelet analysis method automatically drop noise, the threshold of high-frequency coefficient, noise reduction effect and the results of the percentage of wavelet1D.m completion of the input signals of one-dimensional discrete wavelet multi-scale decomposition wavelet2D completion of the input signals of two-dimensional discrete wavelet multi-scale decomposition zigzag.m completed the input of 8* 8 matrix of data collected in accordance with the zigzag order. Platform: |
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Author:zhouhao |
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Description: 利用DCT变化对tif图像进行压缩利用DCT变换进行图像压缩的MATLAB程序-Changes in the use of DCT compression of tif images using DCT transform image compression MATLAB program Platform: |
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Author:ruiomar |
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Description: 已知两个不同图像块亮度数据如下：
（1）分析DCT原理，采用DCT方法，编程并计算相应的DCT系数，分析系数分布特点。
（2）依据视觉特性分析量化表步长的分布特点，完成DCT系数量化。
（3）采用Z形扫描，实现输出数据的统计编码，形成Video stream。
（4）采用IDCT重建图像亮度数据，计算SAD大小，分析产生误差的原因及采用DCT进行数据压缩的原理。（ ）
（5）分别利用左上角1、3、6个系数重建图像，计算相应的SAD，并由此分析直流和低频系数的重要性。
-Known brightness of two different image data block is as follows: (1) Principles of analysis of DCT, the DCT method, program and calculate the corresponding DCT coefficient, analysis of distribution coefficients. (2) quantitative analysis based on visual characteristics of the distribution of long-form features step-by-step to complete the DCT coefficient quantization. (3) the use of Z-scan output data to achieve statistical encoding, the formation of Video stream. (4) the use of the reconstructed image brightness IDCT data to calculate the SAD size, analysis of the causes of errors and the use of DCT for the principle of data compression. () (5), respectively, a factor of 1,3,6 using the upper left corner of the reconstruction of images, calculating the corresponding SAD, and the resulting analysis of DC and the importance of low-frequency coefficients. Platform: |
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Author:张元 |
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Description: 给予matlab的JPEG压缩程序，包含原始压缩图片，程序对灰度bmp图片进行JEPG编码，压缩成以0101形式的编码。JPEG编码先把图象色彩RBG变成亮度Y和色度Cr、Cb，它利用人的视觉对色度不敏感的特点，减少一部分色度数据，以达到压缩。 JPEG采取多种编码方式，包含有行程编码(Run Length Coding)和哈夫曼(Huffman)编码，有很高的压缩比。在编码前，先对数据进行分块，离散余弦变换（DCT）及量化，保留能量大的低频信号，丢弃高频信号以达到压缩。-Given to the JPEG compression matlab program, contains the original compressed image, the program of the grayscale bmp picture JEPG encoded, compressed into a 0101 form of encoding. RBG color coded JPEG image into a first luminance Y and chrominance Cr, Cb, which uses the human visual characteristics is not sensitive to the color, reduce the number of color data to achieve compression. Take a variety of JPEG encoding, includes length coding (Run Length Coding) and Huffman (Huffman) coding, a high compression ratio. In the code before the data block, discrete cosine transform (DCT) and quantization, to retain a large low-frequency signal energy, discarding high-frequency signals in order to achieve compression. Platform: |
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Author: |
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Description: （1）试利用函数dct2，对该图像进行压缩。压缩时可尝试对DCT 变换后的系数采用不同取舍方法，比较其压缩性能。（函数dct2在matlab本身是有的，可以help dct2看看）
（2）结合课本例8.7.2 的量化方法，对每一个经DCT变换后的8×8 矩阵量化（Huffman编码部分可省略），从而实现图像压缩。在一定压缩比的情况下，和⑴给出的图像质量相比较。
（3）用所给的子子程序fast_LOT.m 实现对该图像的变换与压缩，并和（1）得出的图像质量相比较-(1) Test using function dct2, the image is compressed. The compression can try to adopt different choices, the DCT transform coefficients after comparing its compression performance. (Function dct2 the matlab itself is some help dct2 see) (2) combined with the textbook cases 8.7.2 of quantitative methods, 88 each DCT transform matrix quantization (Huffman encoding part can be omitted) thereby achieving the image compression. In the case of a certain compression ratio, and the image quality given by the ⑴ compared. (3) with the given sub-subroutine fast_LOT.m transform and compress the image, and (1) gives the image quality compared Platform: |
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Author:zrf |
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Search - image compression using DCT in Matlab