共查询到20条相似文献,搜索用时 15 毫秒
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Based on the grey model (GM), a simple and fast methodology is developed for lossy image compression. First of all, the image is decomposed into some different-size image windows through the judgement of grey difference level; then the GM (1,1) of grey system theory is used as a fitter to model those window pixels. The proposed algorithms can be contrasted with the conventional compression techniques such as discrete cosine transform or vector quantization (VQ) algorithms in their dynamic modelling sequence and flexible block size. Especially, the compression and decompression process do not require an extra decoder and only utilize the modelling parameters to reconstruct the image by reversing the operation of GM (1,1). Experiments with some (512 x 512) images indicate that not only the average bit number per pixel and peak signal-to-noise ratio but also the coding time and decoding time of this lossy image compression algorithm based on GM (1,1) are better than those of block truncation coding with VQ. 相似文献
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基于小波变换的分类量化图像编码算法 总被引:3,自引:0,他引:3
针对标量量化压缩比小而向量量化压缩速度慢、图像复原效果不理想等弱点,提出了基于小波变换的分类量化图像编码算法(简称“分类量化编码”)。该算法基本思想为:首先将小波变换后的图像高频子带划分为局部快;然后利用文中给出的相对距离最近之值选择方法,依据纹理复杂度和重要性程度将这些局部块划分为4类(平坦、过渡、弱纹理和强纹理);最后对平坦局部块进行向量量化编码,对强纹理局部进行标量量化编码。实验结果表明:该图像压缩算法在压缩速度、图像复原效果、压缩比等方面明显优于零树小波编码和JPEG方法。 相似文献
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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) 相似文献
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针对熵编码的自适应可逆图像预处理方法 总被引:2,自引:1,他引:1
大多数图像编码前所采用的预处理方法都会造成一定程度的信息损失。以提高图像的熵编码效率为目的,提出一种自适应可逆图像预处理方法——基于相邻像素相似性的可逆图像变换,它包括8像素和4像素处理下的多种模式。在对图像做位平面分解后进行基于相邻像素相似性的可逆图像变换,并选择多种变换方式下具有最小熵的变换图像作为预处理输出,其直方图呈现出U型分布。实验结果表明,该预处理方法改变了图像的统计特性,从而提高了图像的压缩比和熵编码效率。 相似文献
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改进的分形矢量量化编码 总被引:1,自引:0,他引:1
为了提高图象的分形矢量量化编码效果,在利用四叉树对图象进行自适应分割的基础上,基于正交基三维分量投影准则,提出了图象块非平面近似方法,进而形成一种新的静态图象分形矢量量化编码方法。该方法首先通过对投影参数进行DPCM编码来构造粗糙图象,然后由此来构成差值图象编码的码书。由于该方法把分形和矢量量化编码结合起来,因此解码时只需查找码书,并仅进行对比度变换。计算机编、解码实验结果表明,该编码方法具有码书不需外部训练,解码也不需迭代等优点,且与其他同类编码器相比,该方法在压缩比和恢复图象质量(PSRN)方面均有明显改善。 相似文献
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《IEEE transactions on audio, speech, and language processing》2006,14(2):524-532
In this paper, we use the Gaussian mixture model (GMM) based multidimensional companding quantization framework to develop two important quantization schemes. In the first scheme, the scalar quantization in the companding framework is replaced by more efficient lattice vector quantization. Low-complexity lattice pruning and quantization schemes are provided for the E/sub 8/ Gossett lattice. At moderate to high bit rates, the proposed scheme recovers much of the space-filling loss due to the product vector quantizers (PVQ) employed in earlier work, and thereby, provides improved performance with a marginal increase in complexity. In the second scheme, we generalize the compression framework to accommodate recursive coding. In this approach, the joint probability density function (PDF) of the parameter vectors of successive source frames is modeled using a GMM. The conditional density of the parameter vector of the current source frame based on the quantized values of the parameter vector of the previous source frames is used to generate a new codebook for every current source frame. We demonstrate the efficacy of the proposed schemes in the application of speech spectrum quantization. The proposed scheme is shown to provide superior performance with moderate increase in complexity when compared with conventional one-step linear prediction based compression schemes for both narrow-band and wide-band speech. 相似文献
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基于二维小波分解的图象编码 总被引:1,自引:0,他引:1
本文给出一个基于二维小波分解来进行图象压缩编码的方法。这里是使用正交小波变换来由行图象分解,得到一个图象的多分辨率表示,各频道分量对图象结构的把握是整体的,从更大程度上解除了图象象素之间的相关性,克服了由JPEG方法进行图象压缩编码而产生的块效应。对图象进行二维正交小波分解后,我们使用CVQ对小波系数进行编码,得到了较高的编码效率和重建图象质量。 相似文献
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Pei-Yin Chen 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2004,34(1):740-746
In this paper, we propose a novel efficient fuzzy prediction algorithm for image vector quantization by using the fact that the pixel values of a block is highly related to those of its adjacent blocks in the same image frame because of its spatial correlation. The experimental results show that our method performs better than other VQ algorithms, such as SOC-VQ, LCIC-VQ, STC-VQ, and DST-VQ, in terms of computational complexity and coding efficiency. 相似文献
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Hybrid sampling is used in both two dimensional transform and hybrid (transform-DPCM) processing of standard digitized images of the GIRL and MOONSCAPE. Maximum variance zonal and threshold samplings are compared with ratios of combination of the two (hybrid sampling), for different data compression ratios. A quantization and bit allocation scheme is also employed and bits per pixel and mean square error between the original and reconstructed images are used as performance criteria, to determine the effectiveness of hybrid sampling when compared to threshold and maximum variance zonal samplings. Optimal ratio in terms of bit rate, mean square error and image quality is sought. 相似文献
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In this paper, a new multi stage vector quantization with energy clustered training set is proposed for color image coding. The input image is applied with orthogonal polynomials based transformation and the energy clustered transformed training vectors are obtained with reduced dimension. The stage-by-stage codebook for vector quantization is constructed from the proposed transformed training vectors so as to reduce computational complexity. This method also generates a single codebook for all the three color components, utilizing the inter-correlation property of individual color planes and interactions among the color planes due to the proposed transformation. As a result, the color image encoding time is only slightly higher than that of gray scale image coding time and in contrast to the existing color image coding techniques, whose time is thrice greater than that of gray scale image coding. The experimental results reveal that only 35 % and 10 % of transform coefficients are sufficient for smaller and larger blocks respectively, for the reconstruction of images with good quality. The proposed multi stage vector quantization technique is faster when compared to existing techniques and yields better trade-off between image quality and block size for encoding. 相似文献
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提出一种基于小波变换静止图像压缩的快速算法.在兼顾压缩比和峰值性噪比的同时,采用离散小波变换的快速算法,对量化和熵编码两部分进行优化,提高了算法的快速性,并经过了实验验证. 相似文献
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Akbar Sheikh Akbari Pooneh Bagheri Zadeh Tom Buggy John Soraghan 《Multimedia Tools and Applications》2012,58(3):569-583
This paper presents a novel Multiresolution, Perceptual and Vector Quantization (MPVQ) based video coding scheme. In the intra-frame
mode of operation, a wavelet transform is applied to the input frame and decorrelates it into its frequency subbands. The
coefficients in each detail subband are pixel quantized using a uniform quantization factor divided by the perceptual weighting
factor of that subband. The quantized coefficients are finally coded using a quadtree-coding algorithm. Perceptual weights
are specifically calculated for the centre of each detail subband. In the inter-frame mode of operation, a Displaced Frame
Difference (DFD) is first generated using an overlapped block motion estimation/compensation technique. A wavelet transform
is then applied on the DFD and converts it into its frequency subbands. The detail subbands are finally vector quantized using
an Adaptive Vector Quantization (AVQ) scheme. To evaluate the performance of the proposed codec, the proposed codec and the
adaptive subband vector quantization coding scheme (ASVQ), which has been shown to outperform H.263 at all bitrates, were
applied to six test sequences. Experimental results indicate that the proposed codec outperforms the ASVQ subjectively and
objectively at all bit rates. 相似文献
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为缓解无线胶囊内镜图像在电子设备以及服务器中的存储压力,提出一种自适应不规则纹理的无损压缩算法。在图像块内,利用扩展角度预测模式寻找与待预测像素最邻近的5个参考像素,并给其中3个参考像素分配不同权重,同时根据邻近像素值梯度变化规律,扩大待预测像素在不规则纹理方向上的预测值选择范围,基于图像块的最小信息熵选择最优的预测值,将真实值与预测值作差获得预测残差,以适应不规则纹理图像。利用跨分量预测模式选择最优的预测系数,构建符合图像块内预测残差分布规律的线性关系,从而消除当前编码像素中3个分量的冗余数据。结合Deflate算法对经多角度预测模式与跨分量预测模式预测后的剩余残差进行熵编码。实验结果表明,该算法在Kvasir-Capsule数据集上的无损压缩比平均为5.81,相比WebP、SAP、MDIP等算法,具有较优的压缩性能,能够有效提高图像的冗余消除率,其中相较WebP算法的冗余消除率提高约1.9%。 相似文献