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Description: 于傅里叶变换的图像加密技术研究
具体是将一幅图像用 fft 变换到频域
在频域中进行加密 我考虑的是通过随机相位来加密的方法，请问用matlab怎样实现
加密后在通过 ifft 得到加密后的图象
-Fourier transform in the image encryption technology to study the details of an image is to use fft transformed to the frequency domain in the frequency domain I consider encryption is through random-phase approach to encryption, Will the use of Matlab how to achieve the adoption of encryption ifft be encrypted images
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Size: 856 |
Author: 李建成 |
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Description: VC编写的高效的图象2D快速傅立叶正变换程序,编译通过.适合256色bmp图象变换.效果和matlab的fft2()没法比,但是程序值得借鉴.适合图象处理初学者,有助于理解傅立叶变换在图象处理中的重要作用.-VC efficient preparation of the image is 2D fast Fourier transform procedures compile. Bmp for 256-color image transformation. Results and Matlab fft2 () no match for, but the procedure is worth learning from. Image processing for beginners, helps to understand Fourier transform in the image processing an important role.
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Size: 84992 |
Author: 李安定 |
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Description: 该程序实现二维的FFT变换，可以对图像做FFT变换，运行速度还可以。-procedures to achieve the two-dimensional FFT transform, the image can be done FFT, can also speed.
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Size: 1024 |
Author: 李文 |
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Description: 于傅里叶变换的图像加密技术研究
具体是将一幅图像用 fft 变换到频域
在频域中进行加密 我考虑的是通过随机相位来加密的方法，请问用matlab怎样实现
加密后在通过 ifft 得到加密后的图象
-Fourier transform in the image encryption technology to study the details of an image is to use fft transformed to the frequency domain in the frequency domain I consider encryption is through random-phase approach to encryption, Will the use of Matlab how to achieve the adoption of encryption ifft be encrypted images
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Size: 1024 |
Author: 李建成 |
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Description: 简单数字图像处理，直方图统计、滤波、均衡、锐化、转置、FFT变换等-Simple digital image processing, histogram statistics, filtering, balance, sharpening, transpose, FFT transform
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Size: 3072 |
Author: 唐新云 |
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Description: 用c语言实现了图像二维快速傅里叶变换，将图像变换到频域进行处理。-Use c language to achieve an image of two-dimensional fast Fourier transform, image transform to the frequency domain for processing.
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Size: 6148096 |
Author: 胡海力 |
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Description: The frequency domain plays an important role in image
processing to smooth, enhance, and detect edges of images. Although
image data typically does not include imaginary values, the fast Fourier
transform (FFT) has been used for obtaining spectra. In this paper,
the fast Hartley transform (FHT) is used to transform two-dimensional
image data. Because the Hartley transform is real valued, it does
not require complex operations. Both spectra and autocorrelations of
two-dimensional ultrasound images of normal and abnormal livers were
computed.
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Size: 4096 |
Author: archit |
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Description: 空载合成孔径雷达系统的研制过程中常需要对某些关键算法和功能原理进行验证，而这些验证用的数据
又不可能完全通过代价昂贵的实际飞行获得，因此通过半实物仿真和信号模拟来获得所需的目标回波数据成为一个有效
的解决手段。-Synthetic Aperture Radar (SAR) simulator of an extended three-dimensional scene is presented. It is based on a facet model for the scene, asymptotic evaluation of SAR unit
response, and two-dimensional fast Fourier transform (FFT) code
for data processing. Prescribed statistics of the model account for
a realistic speckle of the image. The simulator is implemented in a code (SARAS) whose performance is described and illustrated by a number of examples.
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Size: 1202176 |
Author: nico |
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Description: 本文论述并设计实现了一个脱机自由手写体数字识别系统。文中首先对待识别数字的预处理进行了介绍，包括二值化、平滑滤波、规范化、细化等图像处理方法；其次，探讨了如何提取数字字符的结构特征和笔划特征，并详细地描述了知识库的构造方法；最后采用了以知识库为基础的模板匹配识别方法,并以MATLAB作为编程工具实现了具有友好的图形用户界面的自由手写体数字识别系统。实验结果表明，本方法具有较高的识别率，并具有较好的抗噪性能。-In this paper, designed and implemented an off-line handwritten numeral recognition system. The paper first pre-treatment identification numbers were introduced, including binarization, smoothing filter, normalization, thinning and other image processing methods secondly, to explore how to extract the number of characters in the structural characteristics and stroke features, and described in detail Knowledge of construction methods finally adopted in order to Knowledge-based template matching recognition method, and to MATLAB as a programming tool to achieve a friendly graphical user interface handwritten numeral recognition system. The experimental results show that this method has higher recognition rate, and has good anti-noise performance.
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Size: 350208 |
Author: zhangying |
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Description: 数字图像处理中的滤波和傅里叶压缩，包括理想低通滤波器，巴特沃茨高通滤波器，高斯带通滤波器，高斯带阻滤波器，FFT图像压缩。附原图像和处理后的图像截图。-Digital image processing in filtering and Fourier compression, including the design of an ideal low-pass filter, design Batewoci high-pass filter, bandpass filter design Gaussian, Gaussian band stop filter, FFT image compression. Attached to the original image and processed image capture.
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Size: 272384 |
Author: 刘雨相 |
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Description: 二维傅里叶变换,对图像进行二维傅里叶变换处理-Two-Dimensional Fast Fourier Transform
The purpose of this project is to develop a 2-D FFT program "package" that will be used
in several other projects that follow. Your implementation must have the capabilities to:
(a) Multiply the input image by (-1)x+y to center the transform for filtering.
(b) Multiply the resulting (complex) array by a real function (in the sense that the
the real coefficients multiply both the real and imaginary parts of the transforms).
Recall that multiplication of two images is done on pairs of corresponding elements.
(c) Compute the inverse Fourier transform.
(d) Multiply the result by (-1)x+y and take the real part.
(e) Compute the spectrum.
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Size: 1024 |
Author: solo |
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Description: 2010年ICIP最新文章关于图像复原，提出了2D NHA算法，实验证明了该算法的优越性能。-In this study, we develop a technique for image restoration
The proposed method is based on the 2D non-harmonic analy-
sis (2D NHA). The 2D NHA algorithm assigns an initial value
by using the spectrum of the maximum amplitude, which is
obtained by FFT. This value is converged to a global min-
imum by using the steepest descent method and Newton’s
method. And, an image recovery method was proposed by
improving the cost function of 2D NHA as excluding the
missing region. To verify the effi cacy of the proposed method
simulation is carried out using a damaged image. The simula-
tion results show that a high-quality image is obtained when
the missing region is consist of periodicity. In both the ob-
jective and the subjective comparisons, the qualities of the
images recovered using the proposed method are the most fa-
vorable in all cases.
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Size: 140288 |
Author: kongsuhong |
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Description: MONOFILT - Apply monogenic filters to an image to obtain 2D analytic signal
Implementation of Felsberg s monogenic filters
Usage: [f, h1f, h2f, A, theta, psi] = ...
monofilt(im, nscale, minWaveLength, mult, sigmaOnf, orientWrap)
3 4 2 0.65 1/0
Arguments:
The convolutions are done via the FFT. Many of the parameters relate
to the specification of the filters in the frequency plane.- MONOFILT - Apply monogenic filters to an image to obtain 2D analytic signal
Implementation of Felsberg s monogenic filters
Usage: [f, h1f, h2f, A, theta, psi] = ...
monofilt(im, nscale, minWaveLength, mult, sigmaOnf, orientWrap)
3 4 2 0.65 1/0
Arguments:
The convolutions are done via the FFT. Many of the parameters relate
to the specification of the filters in the frequency plane.
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Size: 3072 |
Author: seshu babu v |
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Description: Matlab图像处理库的二维傅立叶变换，时域和频域的尺寸相同，这导致傅立叶变换运算低效，这里是一个优化后的算法的代码。-Many image processing applications require an extensive usage
of FFT2 routine (or, in the most general case, a N-dimensional
FFT) of matrices having the same dimensions. In these cases Matlab
FFT2 can result extremely inefficient.
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Size: 185344 |
Author: Tom |
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Description: 功能： 菲涅耳衍射的S-FFT计算
执行：调入一图像，计算平面波照射下给定波长及距离的衍射场振幅图像
-Given wavelength and the distance of the diffraction field amplitude image function: Fresnel diffraction of the S-FFT calculation of Execution: transferred to an image, computing the plane wave illumination
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Size: 696320 |
Author: liutian |
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Description: 产生右图所示图像f1(m,n)，其中图像大小为256×256，中间亮条为128
×32，暗处=0，亮处=100。对其进行FFT：
① 同屏显示原图f1(m,n)和FFT(f1)的幅度谱图；
② 若令f2(m,n)=（-1）m+n f1(m,n)，重复以上过程，比较二者幅度
谱的异同，简述理由；
③ 若将f2(m,n)顺时针旋转90 度得到f3(m,n)，试显示FFT(f3)的幅
度谱，并与FFT(f2)的幅度谱进行比较；
④ 若将f1(m,n) 顺时针旋转90 度得到f4(m,n)，令f5(m,n)=f1(m,n)+f4(m,n)，试显
示FFT(f5)的幅度谱，并指出其与FFT(f1)和FFT(f4)的关系；
⑤ 若令f6(m,n)=f2(m,n)+f3(m,n)，试显示FFT(f6)的幅度谱，并指出其与FFT(f2)和
FFT(f3)的关系，比较FFT(f6)和FFT(f5)的幅度谱。-Generating an image f1 (m, n) shown in the figure, wherein the image size is 256 256, the intermediate light bar 128 32 0 = dark, bright Department 100. Its FFT: ① screen display picture f1 (m, n) and the FFT (f1) of the amplitude spectrum ② If so f2 (m, n) = (-1) m+n f1 (m, n), repeat The above process, comparing the amplitude spectrum of the similarities and differences between the two, brief reasons ③ If f2 (m, n) 90 degrees clockwise to get f3 (m, n), try to display FFT (f3) the amplitude spectrum and with the FFT (f2) comparing the amplitude spectrum ④ If f1 (m, n) obtained by 90 degrees clockwise f4 (m, n), so f5 (m, n) = f1 (m, n)+f4 (m, n ), try to display FFT (f5) amplitude spectrum, and pointed out its relationship with the FFT (f1) and FFT (f4) of ⑤ If so f6 (m, n) = f2 (m, n)+f3 (m, n) and try to display the FFT (f6) amplitude spectrum, and pointed out its relationship with the FFT (f2) and FFT (f3), comparing FFT (f6) and FFT (f5) amplitude spectrum.
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Size: 1024 |
Author: 李欣 |
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Description: The discrete cosine transform (DC T) represents an image as a sum of
sinusoids of varying magnitudes and frequencies. The dct2 function
computes the two-dimensional discrete cosine transform (DC T) of an
image. The DC T has the property that, for a typical image, most of the
visually significant information about the image is concentrated in just a few
coefficients of the DC T. For this reason, the DC T is often used in image
compression applications. For example, the DC T is at the heart of the international
standard lossy image compression algorithm known as JPEG. (The name comes
from the working group that developed the standard: the Joint Photographic
Experts Group). In practice, the DC T is normally implemented using the same basic
efficiency techniques as in FFT algorithms
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Size: 3049472 |
Author: cj |
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Description: here a file to computee fourier tranform of an image
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Size: 1024 |
Author: Malik Masood Ahmed |
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Description: Skew detection and correction is very important task before pre-processing of an image and it is a major problem in scanned documents, if it
not detected correctly it will lead wrong result in future during image analysis. During the scanning of the document, skew is being often introduced in the
document image. To measure the processed time and speed taken by skew detection algorithm, the Fast Fourier Transform (FFT) technique is applied
as it is fast approach for finding the angle of skewed document. This technique is used by firstly applying DCT compression and thresholding on image
to reduce timing computation and after that Fourier spectrum is obtained. Further this spectrum is divided into four quadrants and detected skewed angle
of each quadrant is measured. And finally Input image is rotated by using bilinear interpolation method.
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Size: 77824 |
Author: ammar |
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Description: The following Matlab project contains the source code and Matlab examples used for use fourier interpolation to increase sampling of an image. also includes an optional filter. . Zero-pads the FFT of an image up to the desired size, then performs IFFT on larger array.
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Size: 2048 |
Author: zoya |
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