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NEW FAST ALGORITHM OF 2-D DISCRETE COSINE TRANSFORM
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作者 王新成 周晓明 +1 位作者 卢颉 朱维乐 《Journal of Electronics(China)》 1995年第3期270-275,共6页
In this paper, a new algorithm for the fast computation of a 2-D discrete cosine transform (DCT) is presented. It is shown that the N×N DCT, where N = 2m, can be computed using only N 1-D DCT’s and additions, in... In this paper, a new algorithm for the fast computation of a 2-D discrete cosine transform (DCT) is presented. It is shown that the N×N DCT, where N = 2m, can be computed using only N 1-D DCT’s and additions, instead of using 2N 1-D DCT’s as in the conventional row-column approach. Hence the total number of multiplications for the proposed algorithm is only half of that required for the row-column approach, and is also less than that of most of other fast algorithms, while the number of additions is almost comparable to that of others. 展开更多
关键词 image processing discrete cosine transform fast algorithm
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Implementation of Variable Tone Variable Bits Gray-Scale Image Stegnography Using Discrete Cosine Transform 被引量:2
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作者 Sahib Khan Muhammad Nawaz Khan +2 位作者 Somia Iqbal Syed Yaqoob Shah Nasir Ahmad 《Journal of Signal and Information Processing》 2013年第4期343-350,共8页
Secure exchange of information is the basic need of modern digital world of e-communication which is achieved either by encrypting information or by hiding information in other information called cover media. Conceali... Secure exchange of information is the basic need of modern digital world of e-communication which is achieved either by encrypting information or by hiding information in other information called cover media. Concealing information requires a well designed technique of Stegnography. This work presents a technique, variable tone variable bits (VTVB) Stegnography, to hide information in a cover image. The VTVB Stegnography hides variable data in discrete cosine transform (DCT) coefficients of the cover image. VTVB Stegnography provides variable data hiding capacity and variable distortion. Additional large data hiding this technique provide extra security due to the large key size making VTVB Stegnography technique much more immune to steganalysis. The hiding makes the existence of information imperceptible for steganalysis and the key of keeping a secret makes the recovering of information difficult for an intruder. The key size is depending on cover image and numbers of bits of discrete cosine transform (DCT) coefficients used for information embedding. This is a very flexible technique and can be used for low payload applications, e.g. watermarking to high payload applications, e.g. network Stegnography. 展开更多
关键词 Information Security image processing Stegnography STEGANALYSIS discrete cosine transform (DCT)
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A FAST ALGORITHM FOR DISCRETE HARTLEY TRANSFORM OF ARBITRARY LENGTH
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作者 曾泳泓 《Journal of Electronics(China)》 1993年第3期209-216,共8页
DHT of length p<sup>l</sup>q(p is odd and q is arbitrary) is turned into p<sup>l</sup> DHTs of length qand some additional operations, while the additional operations only involves the comput... DHT of length p<sup>l</sup>q(p is odd and q is arbitrary) is turned into p<sup>l</sup> DHTs of length qand some additional operations, while the additional operations only involves the computation ofcos-DFT and sin-DFT with length p. If the length of a DHT is p<sub>1</sub><sup>l<sub>1</sub></sup>…P<sub>N</sub><sup>l<sub>N</sub></sup>2<sup>l</sup>(P<sub>1</sub>…,P<sub>N</sub> are oddprimes), a fast algorithm is obtained by the similar recursive technique. Therefore, the algorithmcan compute DHT of arbitrary length. The paper also Proves that operations for computingDHT of length N by the algorithm are no more than O(Nlog<sub>2</sub>N), when the length is N=p<sup>l</sup>,operations of the algorithm are fewer than that of other known algorithms. 展开更多
关键词 SIGNAL processing discrete Hartley transform fast algorithm
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Experiments in Parallelizing the Type IV Discrete Cosine Transform
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《Computer Technology and Application》 2012年第4期305-314,共10页
The Fourier transform is very important to numerous applications in science and engineering. However, its usefulness is hampered by its computational expense. In this paper, in an attempt to develop a faster method fo... The Fourier transform is very important to numerous applications in science and engineering. However, its usefulness is hampered by its computational expense. In this paper, in an attempt to develop a faster method for computing Fourier transforms, the authors present parallel implementations of two new algorithms developed for the type IV Discrete Cosine Transform (DCT-IV) which support the new interleaved fast Fourier transform method. The authors discuss the realizations of their implementations using two paradigms. The first involved commodity equipment and the Message-Passing Interface (MPI) library. The second utilized the RapidMind development platform and the Cell Broadband Engine (BE) processor. These experiments indicate that the authors' rotation-based algorithm is preferable to their lifting-based algorithm on the platforms tested, with increased efficiency demonstrated by their MPI implementation for large data sets. Finally, the authors outline future work by discussing an architecture-oriented method for computing DCT-IVs which promises further optimization. The results indicate a promising fresh direction in the search for efficient ways to compute Fourier transforms. 展开更多
关键词 discrete cosine transform parallel algorithms fast Fourier transforms ROTATION LIFTING MPI (message-passing interface) Cell BE (broadband engine).
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A fast algorithm for n-D discrete cosine transform
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作者 王智顺 李文化 何振亚 《Science China(Technological Sciences)》 SCIE EI CAS 1998年第1期45-54,共10页
A generalized fast computational algorithm for the n -dimensional discrete cosine transform ( n- D DCT) of length N=2 m(m≥2) is presented. The developed algorithm is theoretically proved and its efficiency is evaluat... A generalized fast computational algorithm for the n -dimensional discrete cosine transform ( n- D DCT) of length N=2 m(m≥2) is presented. The developed algorithm is theoretically proved and its efficiency is evaluated. The theoretical results show that compared with the conventional method to compute the 1-D DCTs in n directions, the number of multiplications needed by this algorithm is only 1/n of that required by the conventional method; for the total number of additions, it is a bit more when N≤8 and much less when N≥16 than the coventional one. To validate the proposed algorithm, the case when n=3 is taken as an example and applied to the motion picture compression. The results show that the proposed method is superior to MPEG-2. 展开更多
关键词 discrete cosine transform MULTIDIMENSIONAL signal processing fast algorithm MPEG-2.
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Fast Attack Algorithm for JPEG Image Encryption with Block Position Shuffle
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作者 LI Shanshan GUO Yali +1 位作者 HUANG Jiaxin GAO Ruoyun 《Journal of Shanghai Jiaotong university(Science)》 2025年第5期976-987,共12页
For traditional JPEG image encryption,block position shuffling can achieve a better encryption effect and is resistant to non-zero counting attack.However,the numbers of non-zero coefficients in the 8×8 sub-block... For traditional JPEG image encryption,block position shuffling can achieve a better encryption effect and is resistant to non-zero counting attack.However,the numbers of non-zero coefficients in the 8×8 sub-blocks are unchanged using block position shuffle.For this defect,this paper proposes a fast attack algorithm for JPEG image encryption based on inter-block shuffle and non-zero quantization discrete cosine transformation coefficient attack.The algorithm analyzes the position mapping relationship before and after encryption of image blocks by detecting the pixel values of an image by the designed plaintext image.Then the preliminary attack result of the image blocks can be obtained from the inverse mapping relationship.Finally,the final attack result of the algorithm is generated according to the numbers of non-zero coefficients in each 8×8 block of the preliminary attack result.Every 8×8 block position is related with its number of non-zero discrete cosine transform coefficients in the designed plaintext.It is verified that the main content of the original image could be obtained without knowledge of the encryption algorithm and keys in a relatively short time. 展开更多
关键词 JPEG image inter-block shuffle discrete cosine transform coefficients non-zero coefficients fast attack
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A Review of Image Steganography Based on Multiple Hashing Algorithm 被引量:1
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作者 Abdullah Alenizi Mohammad Sajid Mohammadi +1 位作者 Ahmad A.Al-Hajji Arshiya Sajid Ansari 《Computers, Materials & Continua》 SCIE EI 2024年第8期2463-2494,共32页
Steganography is a technique for hiding secret messages while sending and receiving communications through a cover item.From ancient times to the present,the security of secret or vital information has always been a s... Steganography is a technique for hiding secret messages while sending and receiving communications through a cover item.From ancient times to the present,the security of secret or vital information has always been a significant problem.The development of secure communication methods that keep recipient-only data transmissions secret has always been an area of interest.Therefore,several approaches,including steganography,have been developed by researchers over time to enable safe data transit.In this review,we have discussed image steganography based on Discrete Cosine Transform(DCT)algorithm,etc.We have also discussed image steganography based on multiple hashing algorithms like the Rivest–Shamir–Adleman(RSA)method,the Blowfish technique,and the hash-least significant bit(LSB)approach.In this review,a novel method of hiding information in images has been developed with minimal variance in image bits,making our method secure and effective.A cryptography mechanism was also used in this strategy.Before encoding the data and embedding it into a carry image,this review verifies that it has been encrypted.Usually,embedded text in photos conveys crucial signals about the content.This review employs hash table encryption on the message before hiding it within the picture to provide a more secure method of data transport.If the message is ever intercepted by a third party,there are several ways to stop this operation.A second level of security process implementation involves encrypting and decrypting steganography images using different hashing algorithms. 展开更多
关键词 image steganography multiple hashing algorithms Hash-LSB approach RSA algorithm discrete cosine transform(DCT)algorithm blowfish algorithm
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Several Algorithms for Manipulating Compressed Images in JPEG
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作者 王世铀 郭福顺 赵忠桥 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1998年第3期45-48,共4页
Currently,in multimedia and image processing technologies, implementing special kinds of image manipulation operations by dealing directly with the compressed image is a work worthy to be concerned with. Theoretical a... Currently,in multimedia and image processing technologies, implementing special kinds of image manipulation operations by dealing directly with the compressed image is a work worthy to be concerned with. Theoretical analysis and experiment haVe indicated that some kinds of image processing works can be done very well by dealing with compressed image. In Ans paper, we give some efficient image manipulation operation algorithms operating on the compressed image data. These algorithms have advantages in computing complexity, storage space retirement and image quality. 展开更多
关键词 image Manipulation Operation Compress algorithm discrete cosine transform RUN Length CODE HUFFMAN CODE
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Image auto-zoom technology for AFM automation 被引量:2
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作者 刘文良 钱建强 李渊 《Optoelectronics Letters》 EI 2009年第2期143-146,共4页
For the case of atomic force microscope (AFM) automation, we extract the most valuable sub-region of a given AFM image automatically for succeeding scanning to get the higher resolution of interesting region. Two obje... For the case of atomic force microscope (AFM) automation, we extract the most valuable sub-region of a given AFM image automatically for succeeding scanning to get the higher resolution of interesting region. Two objective functions are sum- marized based on the analysis of evaluation of the information of a sub-region, and corresponding algorithm principles based on standard deviation and Discrete Cosine Transform (DCT) compression are determined from math. Algorithm realizations are analyzed and two selec... 展开更多
关键词 algorithms cosine transforms discrete cosine transforms FUNCTIONS image processing
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A Triple-Channel Encrypted Hybrid Fusion Technique to Improve Security of Medical Images 被引量:1
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作者 Ahmed S.Salama Mohamed Amr Mokhtar +2 位作者 Mazhar B.Tayel Esraa Eldesouky Ahmed Ali 《Computers, Materials & Continua》 SCIE EI 2021年第7期431-446,共16页
Assuring medical images protection and robustness is a compulsory necessity nowadays.In this paper,a novel technique is proposed that fuses the wavelet-induced multi-resolution decomposition of the Discrete Wavelet Tr... Assuring medical images protection and robustness is a compulsory necessity nowadays.In this paper,a novel technique is proposed that fuses the wavelet-induced multi-resolution decomposition of the Discrete Wavelet Transform(DWT)with the energy compaction of the Discrete Wavelet Transform(DCT).The multi-level Encryption-based Hybrid Fusion Technique(EbhFT)aims to achieve great advances in terms of imperceptibility and security of medical images.A DWT disintegrated sub-band of a cover image is reformed simultaneously using the DCT transform.Afterwards,a 64-bit hex key is employed to encrypt the host image as well as participate in the second key creation process to encode the watermark.Lastly,a PN-sequence key is formed along with a supplementary key in the third layer of the EbHFT.Thus,the watermarked image is generated by enclosing both keys into DWT and DCT coefficients.The fusions ability of the proposed EbHFT technique makes the best use of the distinct privileges of using both DWT and DCT methods.In order to validate the proposed technique,a standard dataset of medical images is used.Simulation results show higher performance of the visual quality(i.e.,57.65)for the watermarked forms of all types of medical images.In addition,EbHFT robustness outperforms an existing scheme tested for the same dataset in terms of Normalized Correlation(NC).Finally,extra protection for digital images from against illegal replicating and unapproved tampering using the proposed technique. 展开更多
关键词 Medical image processing digital image watermarking discrete wavelet transforms discrete cosine transform encryption image fusion hybrid fusion technique
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Improving Reconstructed Image Quality via Hybrid Compression Techniques 被引量:1
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作者 Nancy Awadallah Awad Amena Mahmoud 《Computers, Materials & Continua》 SCIE EI 2021年第3期3151-3160,共10页
Data compression is one of the core fields of study for applications of image and video processing.The raw data to be transmitted consumes large bandwidth and requires huge storage space as a result,it is desirable to... Data compression is one of the core fields of study for applications of image and video processing.The raw data to be transmitted consumes large bandwidth and requires huge storage space as a result,it is desirable to represent the information in the data with considerably fewer bits by the mean of data compression techniques,the data must be reconstituted very similarly to the initial form.In this paper,a hybrid compression based on Discrete Cosine Transform(DCT),DiscreteWavelet Transform(DWT)is used to enhance the quality of the reconstructed image.These techniques are followed by entropy encoding such as Huffman coding to give additional compression.Huffman coding is optimal prefix code because of its implementation is more simple,faster,and easier than other codes.It needs less execution time and it is the shortest average length and the measurements for analysis are based upon Compression Ratio,Mean Square Error(MSE),and Peak Signal to Noise Ratio(PSNR).We applied a hybrid algorithm on(DWT–DCT 2×2,4×4,8×8,16×16,32×32)blocks.Finally,we show that by using a hybrid(DWT–DCT)compression technique,the PSNR is reconstructed for the image by using the proposed hybrid algorithm(DWT–DCT 8×8 block)is quite high than DCT. 展开更多
关键词 image compression discrete cosine transform PSNR discrete wavelet transform hybrid algorithm
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Hankel矩阵的离散Cosine变换的快速算法
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作者 汪祥 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2005年第4期461-463,共3页
在图像和信号处理研究邻域,经常会涉及到结构矩阵的离散sine、快速傅里叶变换(FFT)及离散cosine变换.文献[6]的作者利用FFT给出了离散cosine变换的一个算法,计算变换矩阵的M个元素所需的计算量和存贮空间分别为O(N2logN)+O(M)和O(N2).... 在图像和信号处理研究邻域,经常会涉及到结构矩阵的离散sine、快速傅里叶变换(FFT)及离散cosine变换.文献[6]的作者利用FFT给出了离散cosine变换的一个算法,计算变换矩阵的M个元素所需的计算量和存贮空间分别为O(N2logN)+O(M)和O(N2).本文利用Hankel矩阵的结构特点导出一递推关系式(见式(8)),给出了Hankel矩阵的离散cosine变换(DCT)的一个快速算法.该算法所需要的存贮空间为O(N),计算变换矩阵的M个元素所需的计算量为O(NlogN)+O(M). 展开更多
关键词 HANKEL矩阵 快速算法 离散 快速傅里叶变换 存贮空间 变换矩阵 递推关系式 结构矩阵 信号处理 结构特点 计算量 FFT 元素 图像
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Generalized Multiscale RBF Networks and the DCT for Breast Cancer Detection 被引量:2
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作者 Carlos Beltran-Perez Hua-Liang Wei Adrian Rubio-Solis 《International Journal of Automation and computing》 EI CSCD 2020年第1期55-70,共16页
The use of the multiscale generalized radial basis function(MSRBF)neural networks for image feature extraction and medical image analysis and classification is proposed for the first time in this work.The MSRBF networ... The use of the multiscale generalized radial basis function(MSRBF)neural networks for image feature extraction and medical image analysis and classification is proposed for the first time in this work.The MSRBF networks hold a simple and flexible architecture that has been successfully used in forecasting and model structure detection of input-output nonlinear systems.In this work instead,MSRBF networks are part of an integrated computer-aided diagnosis(CAD)framework for breast cancer detection,which holds three stages:an input-output model is obtained from the image,followed by a high-level image feature extraction from the model and a classification module aimed at predicting breast cancer.In the first stage,the image data is rendered into a multiple-input-single-output(MISO)system.In order to improve the characterisation,the nonlinear autoregressive with exogenous inputs(NARX)model is introduced to rearrange the available input-output data in a nonlinear way.The forward regression orthogonal least squares(FROLS)algorithm is then used to take advantage of the previous arrangement by solving the system as a model structure detection problem and finding the output layer weights of the NARX-MSRBF network.In the second stage,once the network model is available,the feature extraction takes place by stimulating the input to produce output signals to be compressed by the discrete cosine transform(DCT).In the third stage,we leverage the extracted features by using a clustering algorithm for classification to integrate a CAD system for breast cancer detection.To test the method performance,three different and well-known public image repositories were used:the mini-MIAS and the MMSD for mammography,and the BreaKHis for histopathology images.A comparison exercise was also made between different database partitions to understand the mammogram breast density effect in the performance since there are few remarks in the literature on this factor.Classification results show that the new CAD method reached an accuracy of 93.5%in mini-Mammo graphic image analysis society(mini-MIAS),93.99%in digital database for screening mammography(DDSM)and 86.7%in the BreaKHis.We found that the MSRBF networks are able to build tailored and precise image models and,combined with the DCT,to extract high-quality features from both black and white and coloured images. 展开更多
关键词 Nonlinear system identification image processing discrete cosine transform radial basis functions computer-aided diagnosis neural networks
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The generalized unified computation of multidimensional discrete orthogonal transforms
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作者 成礼智 蒋增荣 张振慧 《Science in China(Series F)》 2001年第6期401-411,共11页
By introducing a form of reorder for multidimensional data, we propose a unified fast algo-rithm that jointly employs one-dimensional W transform and multidimensional discrete polynomial trans-form to compute eleven t... By introducing a form of reorder for multidimensional data, we propose a unified fast algo-rithm that jointly employs one-dimensional W transform and multidimensional discrete polynomial trans-form to compute eleven types of multidimensional discrete orthogonal transforms, which contain three types of m-dimensional discrete cosine transforms ( m-D DCTs) ,four types of m-dimensional discrete W transforms ( m-D DWTs) ( m-dimensional Hartley transform as a special case), and four types of generalized discrete Fourier transforms ( m-D GDFTs). For real input, the number of multiplications for all eleven types of the m-D discrete orthogonal transforms needed by the proposed algorithm are only 1/m times that of the commonly used corresponding row-column methods, and for complex input, it is further reduced to 1/(2m) times. The number of additions required is also reduced considerably. Furthermore, the proposed algorithm has a simple computational structure and is also easy to be im-plemented on computer, and the numerical experiments show that the computational efficiency is con-sistent with the theoretic analysis. 展开更多
关键词 multidimensional signal processing fast algorithm multidimensional discrete Fourier transform multidimensional discrete cosine transform multidimensional discrete W transform.
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基于人类视觉系统的自适应水印嵌入算法 被引量:20
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作者 陆哲明 姜守达 董寒丽 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2003年第2期138-141,共4页
为了保证水印算法的良好性能 ,在许多文献中提出自适应水印技术 .但是 ,大多数算法根据单一参数对图像块进行分类 ,无法实现最优嵌入 .为此 ,提出了一种新颖的基于DCT变换域的自适应数字水印嵌入算法 .该算法首先将原始图像块按照图像... 为了保证水印算法的良好性能 ,在许多文献中提出自适应水印技术 .但是 ,大多数算法根据单一参数对图像块进行分类 ,无法实现最优嵌入 .为此 ,提出了一种新颖的基于DCT变换域的自适应数字水印嵌入算法 .该算法首先将原始图像块按照图像块的多个特性参数分成不同的类 ,在嵌入过程中考虑到人类视觉系统 (HVS)的特点 ,在不同类的块中嵌入不同的水印能量 ,从而使算法具有自适应能力 .仿真实验表明 ,该算法对常见的一些数字图像处理操作具有较强的鲁棒性 。 展开更多
关键词 算法 自适应水印 人类视觉系统 离散余弦变换 数字水印 最优嵌入 信息安全 图像处理
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DCT和LBP特征融合的人脸识别 被引量:18
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作者 李建科 赵保军 +1 位作者 张辉 焦继超 《北京理工大学学报》 EI CAS CSCD 北大核心 2010年第11期1355-1359,共5页
提出一种特征融合的人脸识别新方法.该方法将人脸图像中少量的低频离散余弦变换(DCT)系数用作人脸的频域特征;把人脸图像规则地分成多个子块,计算每个子块的局部二值图(LBP)编码直方图.这些子块的LBP直方图连接成一个空域全局直方图,作... 提出一种特征融合的人脸识别新方法.该方法将人脸图像中少量的低频离散余弦变换(DCT)系数用作人脸的频域特征;把人脸图像规则地分成多个子块,计算每个子块的局部二值图(LBP)编码直方图.这些子块的LBP直方图连接成一个空域全局直方图,作为人脸的描述向量.这个描述向量经过PCA降维后作为人脸的LBP特征.DCT特征和LBP特征分别归一化,然后进行特征融合.在ORL人脸库上的实验显示了所提方法比单独采用DCT或LBP特征的人脸识别有较好的性能改善. 展开更多
关键词 图像处理 人脸识别 特征融合 离散余弦变换 局部二值图
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采用离散余弦变换的小波图像去噪方法 被引量:9
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作者 芮挺 王金岩 +1 位作者 沈春林 丁健 《光电工程》 EI CAS CSCD 北大核心 2005年第1期51-54,共4页
提出一种通过对小波域中噪声能量的估计来进行去噪的新方法。算法采用离散余弦变换(DCT)提取小波系数的主要特征,无需对噪声方差进行估计。对图像进行小波分解,利用 DCT对高频子带进行局部特征提取;利用部分 DCT 系数对小波系数进行重建... 提出一种通过对小波域中噪声能量的估计来进行去噪的新方法。算法采用离散余弦变换(DCT)提取小波系数的主要特征,无需对噪声方差进行估计。对图像进行小波分解,利用 DCT对高频子带进行局部特征提取;利用部分 DCT 系数对小波系数进行重建,并以重建系数的平均能量作为局部噪声能量的估计;去除原小波系数中的噪声分量后,进行小波逆变换,得到去噪后的图像。实验证明,其峰值信噪比(PSNR)比通常的阈值萎缩法提高了 2-4dB。 展开更多
关键词 图像处理 小波变换 离散余弦变换 去噪
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基于DCT变换的图像融合方法研究 被引量:30
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作者 楚恒 朱维乐 《光学精密工程》 EI CAS CSCD 北大核心 2006年第2期266-273,共8页
提出了一种基于离散余弦变换(DCT)以及一种结合小波变换与DCT变换的图像融合新方法。前者将源图像进行分块DCT变换,依据DCT系数的高频能量,对源图像的对应区域进行融合。后者利用DCT系数的高频能量对小波分解后得到的低频予幽进行... 提出了一种基于离散余弦变换(DCT)以及一种结合小波变换与DCT变换的图像融合新方法。前者将源图像进行分块DCT变换,依据DCT系数的高频能量,对源图像的对应区域进行融合。后者利用DCT系数的高频能量对小波分解后得到的低频予幽进行融合,同时以此为依据对小波最高分解层的小波高频系数进行选择,其他分解层的小波高频系数依据最大局部方差准则进行融合。依照平均误差、峰值信噪比以及均方根误差等客观评价标准,将新方法与其他常用的基于小波变换或DCT变换的融合方法进行了比较。实验结果表明,结合小波变换与DCT变换的图像融合新方法获得的融合效果优于其他方法。该疗法与常用的基于小波变换的融合方法相比,其平均误差减少了40.8%~69.5%,峰值信噪比提高了9.9%~15.6%,均方根误差减少了34.8%~47.5%,评价结果与日视效果相吻合,表明该方法能有效地提高图像融合的质量。基于DCT变换的图像融合新方法的融合效果仅次于结合小波变换与DCT变换的图像融合新方法且其计算量相对较少,适用于实时处理。 展开更多
关键词 图像融合 DCT变换 图像处理 小波变换 压缩域
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半色调图像中数据隐藏算法 被引量:15
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作者 牛少彰 钮心忻 +1 位作者 杨义先 胡文庆 《电子学报》 EI CAS CSCD 北大核心 2004年第7期1180-1183,共4页
在许多打印和出版应用中 ,需要在半色调图像中嵌入数据用于作品的版权保护和认证 .本文提出了一种半色调图像中数据隐藏的算法 ,该算法利用DCT的中频系数比较法进行数字水印信息的嵌入 .在对数字水印信息进行嵌入前 ,首先进行编码 ,转... 在许多打印和出版应用中 ,需要在半色调图像中嵌入数据用于作品的版权保护和认证 .本文提出了一种半色调图像中数据隐藏的算法 ,该算法利用DCT的中频系数比较法进行数字水印信息的嵌入 .在对数字水印信息进行嵌入前 ,首先进行编码 ,转化成比特流 ,然后通过改变DCT中频系数的序关系嵌入数字水印 ,经打印 /扫描后提取出水印 ,实验结果显示 :该算法能够抵抗打印—扫描攻击 ,并且隐藏效果好 ,恢复水印时不需要原始图像 . 展开更多
关键词 打印/扫描 数字水印 半色调图像
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基于频谱融合技术的光学衍射成像彩色图像加密系统 被引量:11
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作者 李婧 吕晓东 +1 位作者 马毛粉 秦怡 《光子学报》 EI CAS CSCD 北大核心 2015年第7期167-172,共6页
提出了一种基于光学衍射成像原理的彩色图像加密方法.首先把彩色图像分成红、绿、蓝三基色分量,并将三基色灰度图像分别作离散余弦变换,得到对应的离散余弦变换谱.保留离散余弦变换谱的主要数据,并用空间复用的方法把这三个主要数据融... 提出了一种基于光学衍射成像原理的彩色图像加密方法.首先把彩色图像分成红、绿、蓝三基色分量,并将三基色灰度图像分别作离散余弦变换,得到对应的离散余弦变换谱.保留离散余弦变换谱的主要数据,并用空间复用的方法把这三个主要数据融合于一个实值图像之中,该图像即为复合频谱.再将此复合频谱送入光学衍射成像系统中加密,得到单幅密文.解密过程为加密过程的逆过程,即首先由单幅密文恢复复合频谱,再由复合频谱分离出三基色图像的部分离散余弦变换谱,再对这些离散余弦变换谱做逆变换得到三基色图像.由于对复合频谱设置了一个特殊数据区,因此在利用相位恢复算法恢复复合频谱的过程中,这些特殊数据作为输入平面的部分振幅支撑,可以避免迭代过程的停滞问题并提高收敛速率,从而完全恢复复合频谱,进而恢复原始图像.本方法可以将一幅彩色图像加密成单幅具有噪声图样的强度密文,同时,解密恢复得到的原始彩色图像具有较高的像质. 展开更多
关键词 信息光学 图像加密 光学衍射 频谱融合技术 彩色图像 离散余弦变换 相位恢复算法 衍射强度
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