共查询到20条相似文献,搜索用时 15 毫秒
1.
Soft compression is a lossless image compression method that is committed to eliminating coding redundancy and spatial redundancy simultaneously. To do so, it adopts shapes to encode an image. In this paper, we propose a compressible indicator function with regard to images, which gives a threshold of the average number of bits required to represent a location and can be used for illustrating the working principle. We investigate and analyze soft compression for binary image, gray image and multi-component image with specific algorithms and compressible indicator value. In terms of compression ratio, the soft compression algorithm outperforms the popular classical standards PNG and JPEG2000 in lossless image compression. It is expected that the bandwidth and storage space needed when transmitting and storing the same kind of images (such as medical images) can be greatly reduced with applying soft compression. 相似文献
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For efficiency and security of image transmission and storage, the joint image compression and encryption method that performs compression and encryption in a single step is a promising solution due to better security. Moreover, on some important occasions, it is necessary to save images in high quality by lossless compression. Thus, a joint lossless image compression and encryption scheme based on a context-based adaptive lossless image codec (CALIC) and hyperchaotic system is proposed to achieve lossless image encryption and compression simultaneously. Making use of the characteristics of CALIC, four encryption locations are designed to realize joint image compression and encryption: encryption for the predicted values of pixels based on gradient-adjusted prediction (GAP), encryption for the final prediction error, encryption for two lines of pixel values needed by prediction mode and encryption for the entropy coding file. Moreover, a new four-dimensional hyperchaotic system and plaintext-related encryption based on table lookup are all used to enhance the security. The security tests show information entropy, correlation and key sensitivity of the proposed methods reach 7.997, 0.01 and 0.4998, respectively. This indicates that the proposed methods have good security. Meanwhile, compared to original CALIC without security, the proposed methods increase the security and reduce the compression ratio by only 6.3%. The test results indicate that the proposed methods have high security and good lossless compression performance. 相似文献
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基于小波的干涉多光谱卫星图像压缩方法 总被引:16,自引:8,他引:16
分析了干涉多光谱卫星遥感图像的成像特性,并根据该类图像对压缩效果的要求提出了一种基于小波分层树集合分割排序(Set Partitioning Hierarchical Trees,SPIHT)的局部图像优先编码方法,通过对图像小波域系数的局部增强,获得了对图像重要数据优先编码的特性,在8倍压缩比的条件下获得了满意的效果。用该方法对多幅干涉多光谱图像进行了测试,测试结果表明:该方法性能优于其他多光 谱卫星遥感图像编码方法,并有利于在实时图像编码系统中得到应用。 相似文献
4.
适于星上应用的高光谱图像无损压缩算法 总被引:1,自引:0,他引:1
针对常见基于预测、变换、矢量量化及其组合的高光谱无损压缩算法压缩比低、压缩算法整体耗时以及硬件实现困难的问题,提出一种适于星上应用的高光谱图像无损压缩算法。首先,沿光谱线的第一谱段图像采用中值预测器进行谱段内预测,其他谱段图像采用谱间预测。谱间预测采用两步双向预测算法,第一步预测采用双向二阶预测器得到参考预测值,第二步预测采用本文提出的改进LUT搜索预测算法得出4个LUT预测值,然后将参考预测值与其比较得出最终的预测值。最后,使用XX-X空间高光谱相机的压缩系统试验设备对该文提出的压缩算法进行了试验验证。结果表明,压缩系统能快速稳定地工作,平均压缩比达到3.05 bpp,与传统方法相比,平均压缩比提高了0.14~2.94 bpp。有效的提高了高光谱图像无损压缩比和解决了压缩算法整体实现困难的问题。 相似文献
5.
Roman Starosolski 《Entropy (Basel, Switzerland)》2020,22(12)
The primary purpose of the reported research was to improve the discrete wavelet transform (DWT)-based JP3D compression of volumetric medical images by applying new methods that were only previously used in the compression of two-dimensional (2D) images. Namely, we applied reversible denoising and lifting steps with step skipping to three-dimensional (3D)-DWT and constructed a hybrid transform that combined 3D-DWT with prediction. We evaluated these methods using a test-set containing images of modalities: Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and Ultrasound (US). They proved effective for 3D data resulting in over two times greater compression ratio improvements than competitive methods. While employing fast entropy estimation of JP3D compression ratio to reduce the cost of image-adaptive parameter selection for the new methods, we found that some MRI images had sparse histograms of intensity levels. We applied the classical histogram packing (HP) and found that, on average, it resulted in greater ratio improvements than the new sophisticated methods and that it could be combined with these new methods to further improve ratios. Finally, we proposed a few practical compression schemes that exploited HP, entropy estimation, and the new methods; on average, they improved the compression ratio by up to about 6.5% at an acceptable cost. 相似文献
6.
为了克服冗余性的Contourlet变换不利于图像压缩的缺陷,提出了噪声修整的Contourlet变换结构,或称为NS-Contourlet.该结构通过迭代的方式减少了量化后的非零系数数量,并且提高了非零系数的逼近能力.设计了一种可采用提升小波实现的拉普拉斯金字塔变换,有效地提高了Contourlet中拉普拉斯金字塔变换部分的速度.提出的NS-Contourlet结构结合EBCOT编码器实现了一种图像压缩算法,并且通过实验验证了该算法的有效性.尤其当低码率压缩(小于0.2 bpp)或者待压缩图像呈现直线纹理特征时,提出算法在主观视觉质量和PSNR指标上均优于JPEG2000,平均PSNR值提高了0.1~0.5 dB. 相似文献
7.
为了克服冗余性的Contourlet变换不利于图像压缩的缺陷,提出了噪声修整的Contourlet变换结构,或称为NS-Contourlet.该结构通过迭代的方式减少了量化后的非零系数数量,并且提高了非零系数的逼近能力.设计了一种可采用提升小波实现的拉普拉斯金字塔变换,有效地提高了Contourlet中拉普拉斯金字塔变换部分的速度.提出的NS-Contourlet结构结合EBCOT编码器实现了一种图像压缩算法,并且通过实验验证了该算法的有效性.尤其当低码率压缩(小于0.2 bpp)或者待压缩图像呈现直线纹理特征时,提出算法在主观视觉质量和PSNR指标上均优于JPEG2000,平均PSNR值提高了0.1~0.5 dB. 相似文献
8.
Multispectral Image Compression for Improvement of Colorimetric and Spectral Reproducibility by Nonlinear Spectral Transform 总被引:1,自引:0,他引:1
Shanshan Yu Yuri Murakami Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》2006,13(5):346-356
The article proposes a multispectral image compression scheme using nonlinear spectral transform for better colorimetric and
spectral reproducibility. In the method, we show the reduction of colorimetric error under a defined viewing illuminant and
also that spectral accuracy can be improved simultaneously using a nonlinear spectral transform called Labplus, which takes
into account the nonlinearity of human color vision. Moreover, we show that the addition of diagonal matrices to Labplus can
further preserve the spectral accuracy and has a generalized effect of improving the colorimetric accuracy under other viewing
illuminants than the defined one. Finally, we discuss the usage of the first-order Markov model to form the analysis vectors
for the higher order channels in Labplus to reduce the computational complexity. We implement a multispectral image compression
system that integrates Labplus with JPEG2000 for high colorimetric and spectral reproducibility. Experimental results for
a 16-band multispectral image show the effectiveness of the proposed scheme. 相似文献
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This article addresses the problem of distributed lossless compression for hyperspectral images and proposes an effective lossless compression algorithm based on classification. First, a band selection algorithm was performed on the hyperspectral images to select those bands with considerable information. Next, the K-means algorithm was performed on those selected bands to obtain the classification map. To make full use of the spectral and spatial correlation, a multilinear regression model was introduced to construct the high-quality side information of each class within the identical block according to the classification map. Subsequently, the (n, k) linear grouping codes were employed to perform the distributed source coding for each class separately. The experimental results showed that the proposed algorithm has a competitive lossless compression performance compared with other state-of-the-art algorithms. 相似文献
13.
基于可逆整数变换的高光谱图像无损压缩 总被引:3,自引:4,他引:3
将变换矩阵分解为三角可逆矩阵(TERM)实现的整数Karhunen-Loève变换(IKLT),具有结构简单、完全可逆和同址运算的优点.将整数KLT和整数小波结合(IWT),提出了一种基于可逆整数变换的去相关方法:将KLT用于去除谱间冗余,并在对KLT的变换矩阵进行TERM分解的过程中,提出基于全局最大值选择主元的优化分解方法,保证了IKLT的准确度,同时明显降低了计算量;空间维的去相关变换采用基于提升结构的整数小波变换,同样保证了变换的完全可逆.采用不同编码策略,对不同场景的高光谱图像数据压缩的实验结果表明,基于整数混合变换的去相关方法能明显提高无损压缩比. 相似文献
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一维核磁共振谱数据的小波变换压缩 总被引:5,自引:1,他引:4
本成功地将小波变换的多尺寸信号分解(MRSD)方法用于一维核磁共振(NMR)信号的数据压缩。将一幅由32768个数据点构成的NMR谱图压缩至512个数据点,仍能在均方差很小(2.7769×10^-4)的情况下很好地重建原始谱图。 相似文献
16.
针对多光谱图像压缩算法现存的时空复杂度高、光谱特性利用不充分等问题,研究了多光谱图像的谱间稀疏等价表示及其聚类实现途径,进而设计了一种基于谱间自适应聚类和小波变换的多光谱图像压缩算法。算法利用吸引力传播聚类产生多光谱图像的谱间稀疏等价表示、在低复杂度下去除图像的谱间冗余,使用二维小波变换去除稀疏表示成分的空间冗余,采用分层树集合分割排序算法(SPIHT)进行压缩编码,并通过误差补偿机制提高多光谱图像重建质量。实验表明,该算法在保证较低时间和空间复杂度的基础上,较SPIHT等同类经典压缩算法,在相同的压缩比下,明显提高了重建图像的峰值信噪比,是一种通用有效的多光谱图像压缩算法。 相似文献
17.
Takeshi Hashimoto Ikutoshi Fukushima Mitsuru Namiki Kimiaki Yamamoto 《Optical Review》1998,5(3):152-157
We show a prototype of a coding system for image compression using vector quantization with an optical inner product processor, whose accuracy is improved by the applying data transformation method. We also present compression effects for gray-scaled images by this system. The system can compress 256X256X8 bits image data within 1.2 seconds under 0.18 compression ratio with an adequate quality. 相似文献
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八种鹅膏菌的傅里叶变换红外光谱的差谱鉴别研究 总被引:1,自引:0,他引:1
利用傅里叶变换红外光谱技术对长柄鹅膏菌、粗鳞白鹅膏菌、格纹鹅膏菌、红黄鹅膏菌、黄柄鹅膏菌、灰疣鹅膏菌、欧氏鹅膏菌、小豹斑鹅膏菌进行傅里叶变换红外光谱研究, 发现八种鹅膏菌的傅里叶变换红外光谱极为相似, 特征区和指纹区(1800~1100 cm-1)的相关系数均大于0.966。因此从这八种鹅膏菌的原始光谱对其鉴别将十分困难。通过差谱技术处理后, 八种鹅膏菌在1800~1100 cm-1范围呈现出各自的特征, 相关分析结果定量反映出它们之间差异较为明显。利用差谱中特征区和指纹区的差异可快速鉴别出该八种鹅膏菌。研究表明: 傅里叶变换红外光谱技术能提供大型真菌所含化学成分的分子结构信息, 结合差谱技术可以鉴别同属下的不同种高等真菌。 相似文献
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Masanori Mitsui Yuri Murakami Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》2005,12(2):69-75
We propose a new method for the color enhancement of multispectral image in the visible wavelength region. The purpose of the proposed method is to explore the weak features contained in a specific wavelength by discounting the major color distribution. Such examination will be valuable in visual inspection applications, for example, a medical examination using color image to find a small spectral change of an abnormal part. In this method, Karhunen-Loeve (KL) transform is applied to multispectral data, and specific wavelength components of only high-order KL coefficients are amplified while low-order coefficients are not changed to retain the major color distribution. In the experiment, this method was applied to multispectral images: a printed test image and a human skin image of a bruised arm were captured by a 16-band multispectral camera. The resultant images were compared with the images obtained by saturation enhancement and that obtained by applying the proposed method to the 3-band image. The method successfully visualized the features, which are almost invisible in natural color images, with less change in background color than saturation enhancement. 相似文献