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图像压缩编码方法综述 总被引:5,自引:0,他引:5
本文对图像压缩的几种经典压缩编码方法进行了汇总和分析。介绍了他们的压缩原理和特点,然后对新一代的编码方法,包括小波变换编码、分形编码和神经网络编码,进行了简要的介绍。指出了各自的优缺点,并对图像压缩编码方法的发展方向进行了展望。 相似文献
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基于分形的图像压缩编码方法是一种全新的编码方法,它利用图像的自相似性及比例特性,通过消除图像的几何冗余度来实现图像数据的压缩,介绍与对比几种分形图像压缩的典型方法。 相似文献
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本文基于小波变换研究了分形图像压缩系统.根据小波系数的能量分布特性,给出了新的小波树定义与分类方法,并在小波域内建立了具有双伸缩因子的压缩映射.在将新的压缩映射应用于图像编码过程时,结合小波嵌入式零树编码思想给出了新的小波分形图像压缩方法.数值实验给出了本文方法与已有方法的比较. 相似文献
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图象压缩的实质是减少图象冗度,各种压缩方法图象冗余度的理解是不同的,其中,分形论者认为图象的不同位置之间在细节上是相似的,百这种相似性愉好是图象的冗余度,分形图象压缩作为一种新的压缩方法业已得取了不亚于DCT编码的结果,并受到越来越多的学者的重视,四叉树法分形图象压缩作为分形压缩的典型方法,易于用递归的程序实现,具有较高的压缩倍烽和压缩速度,但它的压缩信噪比有于压缩速度,特别是高频图象,提出了一种 相似文献
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一种基于小波变换的遥感图像压缩算法 总被引:1,自引:1,他引:0
为验证图像压缩算法122.0-B-0对遥感图像的有效性,在对该算法进行了较为详细的研究后,对该算法进行了软件实现,然后将该算法与JPEG2000、SPIHT算法在压缩效率及压缩速度上进行了比较.实验结果表明:该算法在较低码率下压缩性能与JPEG2000、SPIHT算法相当,在较高码率下压缩性能略微下降,但在相同码率下它的编码速度比JPEG2000快2倍左右,比SPIHT算法约快1.5倍左右,且编解码速度与码率成正比.该算法采用的编码方式相对简单,无反馈操作,可适应于不同内存大小的压缩系统,并采用分段编码有效地防止误码扩散,因此在空间飞行器上具有巨大的应用价值. 相似文献
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为克服快速分形图像编码带来的解码图像质量下降问题,提出了一种神经网络与方差混合编码的快速分形图像编码算法.该算法结合图像子块复杂度与方差值的对应关系,根据每个区块的方差值大小选择适当的映射编码方法,即对于方差值相对小的区块采用方差编码以提高编码速度,对于方差值相对大的区块采用神经网络编码以提高编码质量.该算法可以较好地修正传统分形编码中由于自仿射映射结构限制所带来的解码质量偏低的问题,在大幅提高编码速度的同时,很好地保持了图像的编码质量.实验结果表明,该算法对比基本分形编码算法可以加速24倍,解码图像的质量对比方差快速分形编码算法有1.1dB的提高.同时,该算法的硬件实现比较容易,非常贴近实用化. 相似文献
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B. Priestly Shan O. Jeba Shiney Sharzeel Saleem V. Rajinikanth Atef Zaguia Dilbag Singh 《计算机、材料和连续体(英文)》2022,72(2):2749-2763
Low contrast of Magnetic Resonance (MR) images limits the visibility of subtle structures and adversely affects the outcome of both subjective and automated diagnosis. State-of-the-art contrast boosting techniques intolerably alter inherent features of MR images. Drastic changes in brightness features, induced by post-processing are not appreciated in medical imaging as the grey level values have certain diagnostic meanings. To overcome these issues this paper proposes an algorithm that enhance the contrast of MR images while preserving the underlying features as well. This method termed as Power-law and Logarithmic Modification-based Histogram Equalization (PLMHE) partitions the histogram of the image into two sub histograms after a power-law transformation and a log compression. After a modification intended for improving the dispersion of the sub-histograms and subsequent normalization, cumulative histograms are computed. Enhanced grey level values are computed from the resultant cumulative histograms. The performance of the PLMHE algorithm is compared with traditional histogram equalization based algorithms and it has been observed from the results that PLMHE can boost the image contrast without causing dynamic range compression, a significant change in mean brightness, and contrast-overshoot. 相似文献
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基于颜色属性相关性的图像色差公式的研究 总被引:4,自引:4,他引:0
CIE 色差公式不适合用于复杂图像对间色差预测,为更准确地评价再现图像与原稿之间的颜色差别,提出了一个基于颜色属性相关性的图像色差计算算法。算法的图像色差的计算,采用对比度敏感度函数(CSF)去除图像内容中视觉难以觉察的信息,降低图像内容的空间复杂性,通过对图像对间颜色三属性的相关性分析,确定各色彩属性差的权重。心理物理实验证实,色差公式计算值与主观评价的评分是一致的,表明该算法可用于评价图像对间的颜色差别,也可用于评价压缩方式、图像增强算法以及色域映射算法等的性能。 相似文献
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目的结合人眼视觉特性,研究一种基于改进量化表的JPEG图像压缩算法(JPEG-HVS)。方法利用人眼亮度对比度敏感函数(CSF)生成一种新的量化表,来代替传统JPEG标准推荐的亮度量化表,并通过Matlab7.0对不同种类图像进行了仿真实验。通过计算不同种类图像的压缩质量评价指标,将提出的压缩算法与传统JPEG压缩算法及JPEG区域法进行对比。结果 JPEG-HVS实现的压缩比比JPEG实现的压缩比平均高出53.56%,比JPEG区域法平均高出18.75%。3种压缩方法的峰值信噪比(PSNR)波动不大,JPEG的PSNR值最大,JPEG-HVS次之,平均结构相似度(MSSIM)从大到小排列依次为JPEGJPEG-HVSJPEG区域法。JPEG-HVS编解码所需时间要明显少于JPEG。同时依靠主观评价可以发现,经JPEG-HVS解压的重构图像仍具有良好的视觉特性。结论在保证了压缩质量的同时,提出的JPEG-HVS压缩算法相比于传统JPEG压缩算法、JPEG区域法,可以实现更大的压缩比和更快的编解码速度,更有利于图像的存储与传输。 相似文献
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Image compression has become an inevitable tool along with the advancing medical data acquisition and telemedicine systems. The run-length encoding (RLE), one of the most effective and practical lossless compression techniques, is widely used in two-dimensional space with common scanning forms such as zigzag and linear. In this study, an algorithm which takes advantage of the potential simplicity of the run-length algorithm is devised in a volumetric approach for three-dimensional (3D) binary medical data. The proposed algorithm, namely 3D-RLE, being different from the two-dimensional approach that utilizes only intra-slice correlations, is designed to compress binary volumetric data by employing also the inter-slice correlation between the voxels. Furthermore, it is extended to several scanning forms such as Hilbert and perimeter to determine an optimal scanning procedure coherent with the morphology of the segmented organ in data. The algorithm is employed on four datasets for a comprehensive assessment. Numerical simulation results demonstrated that the performance of the algorithm is 1:30 better than those of the state-of-the-art techniques, on average. 相似文献
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《成像科学杂志》2013,61(2):241-251
AbstractImage hashing is an emerging technology in multimedia security. It uses a short string called image hash to represent an input image and finds applications in image authentication, tamper detection, digital watermark, image indexing, content-based image retrieval and image copy detection. This paper presents a hashing algorithm based on the observation that block entropies are approximately linearly changed after content-preserving manipulations. This is done by converting the input image to a fixed size, dividing the normalised image into non-overlapping blocks, extracting entropies of image blocks and applying a single-level 2D discrete wavelet transform to perform feature compression. Correlation coefficient is exploited to evaluate similarity between hashes. Experimental results show that the proposed algorithm is robust against content-preserving operations, such as JPEG compression, watermark embedding, Gamma correction, Gaussian low-pass filtering, adjustments of brightness and contrast, scaling and small angle rotation. Similarity values between hashes of different images are small, indicating good performances in discriminative capability. 相似文献