fourier transform of image 中文意思是什麼
fourier transform of image
解釋
圖象傅里葉變換-
Sequentially, the author discussed the technologies of medical image 3d visualization according to the clinical applications. with the development of computer, 3d visualization and computer graphics, the 3d visualization of medical images has progressed from fourier transform and convolve inverse projection to mpr ( multi - planar reformation, mpr ) and mtp ( maximum intensity projection, mtp ), nowadays, the real 3d reconstruction method, surface and volume rendering has risen. the image registering, image segmentation, pixel data set construction and 3d special interpolation are the key technologies in medical images 3d reconstruction
隨著計算機技術、三維可視化理論和計算機圖形學的發展，醫學圖像的三維可視化技術也從傅立葉變換、卷積反投影等基本圖像處理演算法，發展到真正的三維重建演算法：面繪制和體繪制；醫學圖像的三維可視化技術的應用也從三維醫學成像發展到虛擬內窺鏡，以及今天的虛擬可視化人體研究；而圖像的配準、圖像分割、體數據集的構建、三維空間插值則是醫學圖像三維可視化實現過程中的關鍵技術環節。 -
In the paper, we describe the whole configuration of the joint transform correlator ; introduce the correlative theories of joint fourier transform in detail ; in order to achieve better correlation result, the nonlinear processing of joint transform power spectrum ( jtps ) is put forward, the effect of jtps laplace sharpening and binary processing to the correlation image is given ; the method of the best binary threshold is determined ; we analyse the correlation image, present the way that removes liquid crystal diffraction spot, direct current spot and image noise, and binarize the correlation image finally
本論文主要對提出的聯合變換相關的整體結構進行了描述；詳細介紹了聯合傅里葉變換的相關理論；為了得到更好的相關結果，本文提出對聯合功率譜進行非線性處理的方法，給出了聯合變換功率譜的拉普拉斯銳化和譜的二值化處理對相關峰圖像的影響及二值化最佳閾值的確定方法；對相關峰圖像信息進行了分析；提出了消除液晶衍射光斑、直流光斑和圖像噪聲的方法；最後對相關峰圖像進行了二值化處理。 -
On the basis of study of fractional fourier transform and its digital computation, the main aim in this paper is to study the applications of fractional fourier transform in lfm signal detection and parameter estimation, to research filtering of lfm signal in the fractional fourier domain and the digital image watermarking in the fractional fourier domain
本文以研究分數階fourier變換的基本理論與應用為目標。在深入分析分數階fourier變換原理和數值實現的基礎上，對lfm信號的檢測與參數估計， lfm信號的分數階fourier域濾波，以及二維分數階fourier變換在數字圖像水印中的應用作了研究和模擬實現。 -
First, resistance to geometrical distortion was obtained by using moment normalization ; second, we focus on the phase of fourier - mellin transform. before detecting watermark, synchronization could be retrieved by using the phase information. to eliminate the influence of pixel value distortion generated during print / scan process, a dft - based robust watermark algorithm was designed, which could successfully detect watermark from a severe distorted image
另一種思路是根據圖像經過旋轉、縮放、平移后，其傅立葉?梅林變換域只有相位受到影響的特點，從其相位中提取幾何失真信息，然後再進行相應的失真補償，從而消除幾何失真的影響；對于列印掃描過程產生的像素值失真，本文也提出了一種基於dft的魯棒性演算法，能在較嚴重的圖像失真情況下，成功檢測水印。 -
Then, based on the theory of discrete fourier transform, discrete cosine transform and discrete wavelet transform, two invisible image watermarking schemes in transform domain are proposed, one is circular symmetric spread spectrum digital image watermarking based on chaotic sequences, the other is the hybrid image watermarking based on wavelet decomposition and discrete cosine transform. finally, the good performance of the two algorithms is verified by some common image processing and attack experiments
在分析了dft 、 dct 、 dwt的理論與演算法的基礎上，提出了兩種基於變換域的圖像隱形水印方案? ?基於混沌序列的圓對稱擴頻水印方案和基於小波分解和餘弦變換結合的水印方案，並通過一些常見的圖像處理及攻擊實驗驗證了這兩種演算法生成水印的性能。 -
In this paper, we firstly design orientation filters based on directional image of fingerprint and employ them to denoise gray - scale image. then, we binarize the gray - scale image with local self - adaptive binarization smoothness algorithm and eliminate the noises from the binary image with fast fourier transform algorithm
本文先基於指紋的方向圖設計出方向濾波器對原圖像進行濾波去噪，然後使用局部平滑閾值自適應二值化演算法，將灰度圖像進行二值化，並採用快速傅氏變換對所得到的二值化圖像進行去噪處理。 -
As the targets flying in groups may spread over several range of cells and their doppler frequencies are time *. varying, a scheme of target number detection in groups on a conventional low *. resolution radar is proposed based on a time *. range *. doppler image cube which is constructed by substituting a time *. frequency transform for the fourier transform in the conventional range *. doppler imaging
針對實際編隊目標在距離上的分佈特性和目標多普勒頻率的變化規律，利用聯合時頻變換代替傳統傅立葉變換，建立目標時間-距離-多普勒立體像，提出一種基於立體像的目標架次檢測方法。 -
Awg possesses an essential function of coherence system - " composing frequency and generating image ". therefore as far as spatial frequency field is concerned, awg is an optical integration of coherent system : two slab waveguides similar to two fourier lenses of one dimension and twice fourier transform of optical signals are realized. here the arrayed waveguide region is frequency spectrum region
Awg具有相干系統的「分頻成譜、合頻成像」這一本質功能，因此若從空間頻域的角度來看， awg就是一個相干系統的光學集成：兩個平板波導類似兩個一維傅里葉透鏡，實現光信號的兩次傅里葉變換；而陣列波導區即為頻譜區。 -
In the far field, the farther the distance, the similar and less distance dependent of the image and radiation pattern of electric and magnetic field, the similar the image of electromagnetic field to the fourier transform of the source current distribution, the less distance dependent of the radiation pattern
在越遠之遠場中，電場與磁場之影像及場型越相似，距離越遠差異越小，電磁場之影像越近似於電流源分佈之富氏轉換。 -
Wavelet transforms overcome the shortcomings of fourier - based techniques because of wavelet ’ s advantage on flexible time - frequency windows. wavelet has been widely applied in numerical analysis, signal processing, and image processing. at present, lifting scheme is new method for constructing wavelets and performing wavelet transform
小波變換克服了傳統fourier變換的不足，在時域和頻域都有良好的局部化特性，在數值分析，信號處理，圖像處理方面得到廣泛的應用，提升技術是構造小波和實現小波變換的一種新方法。 -
Circular symmetric spread spectrum digital image watermarking using chaotic sequences as the watermark takes advantage of the discrete fourier transform properties and spread - spectrum communication techniques to embed a circular symmetric watermark in the frequency domain. the watermark can be detected without the presence of the original image even when the watermarked image suffers geometrical attacks such as translation, rotation and scaling. experimental results show that the proposed scheme has good transparency and highly good robustness to geometric transformations
基於混沌序列的圓對稱擴頻水印方案是以實值混沌序列作為水印，根據離散傅立葉變換的特性並結合通信上的擴頻技術，將一圓對稱水印嵌入到了圖像的頻域中，且即使圖像遭受了平移、旋轉、縮放等幾何攻擊檢測水印也不需要原圖像。 -
Wavelet transform is a time and frequency local transformation and it can withdraw the information from the signal. through the calculate function making the muti - scale analysis it resolves many difficult problems which fourier transformation ca n ' t resolve. in recent years the researches and the applications of wavelet transform on the image compression are flourish, but because wavelet transform is very complicated and its apply has certain localizations
小波變換是一個時間和頻率的局域變換，因而能有效的從信號中提取信息，通過伸縮和平移等運算功能對函數或信號進行多尺度細化分析，解決了fourier變換不能解決的許多困難問題。近年來小波變換在圖像壓縮的研究和應用都十分活躍，但是由於小波的理論很復雜，因此應用起來就有一定的局限性。 -
First, the watermarked image minus the original image is the watermark information. according to the addition property of the fourier transform, a change of spatial domain will cause a change in the frequency domain, which will allow watermarks to be extracted from the watermark information. then, the watermark information is scaled down and embedded in one part of the x - coordinate of the original mesh
提出了三維網格模型盲水印演算法：利用fourier加法性質將水印間接嵌入網格模型頂點坐標上，即先將水印嵌入一個穩定圖像中，然後將嵌入水印后的圖像和原始圖像進行比較得到水印信息，最後將水印信息嵌入網格模型頂點坐標上得到嵌入水印的三維網格模型。 -
2. methods in frequency domain : through a comparative study, wedge and ring feature of fourier transform performs better than other features based on texture spectrum. it represents the directivity, coarseness and regularity of an image
在基於頻率域的紋理分析方法中，分析了基於傅立葉變換的紋理分析方法，經兩組對比實驗，楔環特徵能夠很好的反映圖象紋理的方向性、粗糙性和規律性，在檢索中明顯優于基於頻譜的簡單統計特徵。
分享友人