6.图像的傅立叶变换---数字图像处理实验报告

Internet迅速发展无所不在以及诱人的低价位，的确令众多厂商开始采用这种办法，但Internet天生的开放性特点令人无所适从，安全性又成了问题，公司的机密数据一旦在Internet传输，若没有安全性保障，其后果可想而知。villagetemplesCentralOfficeeveryday,carryouttheirduties.CorrespondencerelatingtoeducationbytheChiefofthefirstsectionmarkedmydraftstatement.Workedafterafewmonths,I'vebeenburiedintheofficialprogram,veryrigidmonotonyofclericalcareer,flavourless.1939of7Augustbetween,County,andSecretarytoIwithtoOfficemeeting,forGovernmentestablishedoneyearstoworkreported,fortimerush,priornotforfullprepared,hadtoinwaybyrankAnnMrdescribedoneyearstoaboutpeople,andfiscal,andbuilt,andtaught,andinsurancefiveaspectsimportantmatters,Iaccordinglydetailednarrativefinishingwritten,completedWujiangGovernmentestablishedoneyearstoofworkreport.TurnbackandforthmonthShanRoad,apartfromtheSecretary,Mrrankfootdiseaseimmobility,bamboocarinsteadofwalkingoutside,squarefoot(exceptformyselfand4guards),thewuxing,peace,SIan,Guangde,doorwayswing,ZhangZhutothedestination--wearingBu.Atdiweitotheimportanttownsoftroopsisdifficulttoaccess,wehavetochangeangles,Shanruggedtrails,Sunandrainontheway,hardshipexceptions,ifthepatrioticandpassionsofthewar,thanthesuccessfulcompletionoftasks.Anoldfrail,rank,long-distanceLawtonregrets,admirable!InNovember1939,IwasadmittedtotheFacultyoflaw,CollegeoflawandpoliticsinShanghai,butresignedfromthepostoffice,bidfarewelltothisshortandmemorablelife.(J)thesiazhenboatburiedJapanesemorningofOctober18,1937,siazhensicktoshunTangQiao-cutters,1fromNanxuntownjiaxingtoJapaneseboats,caughtdraggingbehind3smallboats,loadedwithmilitarygoods.Siazhentoolatetoescape,jumpedashoreJapancatchupwiththeboat,forcinghimtorowaboat.MeanwhilecaughtthemigrantsvillageZhangShun.Siazhenwassickforalongtime,计算机与信息工程学院验证性实验报告专业：通信工程年级/班级：2011级2013—2014学年第一学期课程名称数字图像处理指导教师段新涛本组成员学号姓名实验地点计科楼111实验时间周五5-6节项目名称图像的傅立叶变换实验类型验证性一、实验目的1了解图像变换的意义和手段；2熟悉傅立叶变换的基本性质；3熟练掌握FFT变换方法及应用；4通过实验了解二维频谱的分布特点；5通过本实验掌握利用MATLAB编程实现数字图像的傅立叶变换。6评价人眼对图像幅频特性和相频特性的敏感度。二、实验原理1应用傅立叶变换进行图像处理傅里叶变换是线性系统分析的一个有力工具，它能够定量地分析诸如数字化系统、采样点、电子放大器、卷积滤波器、噪音和显示点等的作用。通过实验培养这项技能，将有助于解决大多数图像处理问题。对任何想在工作中有效应用数字图像处理技术的人来说，把时间用在学习和掌握博里叶变换上是很有必要的。2傅立叶（Fourier）变换的定义对于二维信号，二维Fourier变换定义为：2()(,)(,)juxuyFuvfxyedxdy逆变换：2()(,)(,)juxuyfxyFuvedudv二维离散傅立叶变换为：112()001(,)(,)ikNNjmnNNikFmnfikeN逆变换：112()001(,)(,)ikNNjmnNNmnfikFmneNInternet迅速发展无所不在以及诱人的低价位，的确令众多厂商开始采用这种办法，但Internet天生的开放性特点令人无所适从，安全性又成了问题，公司的机密数据一旦在Internet传输，若没有安全性保障，其后果可想而知。villagetemplesCentralOfficeeveryday,carryouttheirduties.CorrespondencerelatingtoeducationbytheChiefofthefirstsectionmarkedmydraftstatement.Workedafterafewmonths,I'vebeenburiedintheofficialprogram,veryrigidmonotonyofclericalcareer,flavourless.1939of7Augustbetween,County,andSecretarytoIwithtoOfficemeeting,forGovernmentestablishedoneyearstoworkreported,fortimerush,priornotforfullprepared,hadtoinwaybyrankAnnMrdescribedoneyearstoaboutpeople,andfiscal,andbuilt,andtaught,andinsurancefiveaspectsimportantmatters,Iaccordinglydetailednarrativefinishingwritten,completedWujiangGovernmentestablishedoneyearstoofworkreport.TurnbackandforthmonthShanRoad,apartfromtheSecretary,Mrrankfootdiseaseimmobility,bamboocarinsteadofwalkingoutside,squarefoot(exceptformyselfand4guards),thewuxing,peace,SIan,Guangde,doorwayswing,ZhangZhutothedestination--wearingBu.Atdiweitotheimportanttownsoftroopsisdifficulttoaccess,wehavetochangeangles,Shanruggedtrails,Sunandrainontheway,hardshipexceptions,ifthepatrioticandpassionsofthewar,thanthesuccessfulcompletionoftasks.Anoldfrail,rank,long-distanceLawtonregrets,admirable!InNovember1939,IwasadmittedtotheFacultyoflaw,CollegeoflawandpoliticsinShanghai,butresignedfromthepostoffice,bidfarewelltothisshortandmemorablelife.(J)thesiazhenboatburiedJapanesemorningofOctober18,1937,siazhensicktoshunTangQiao-cutters,1fromNanxuntownjiaxingtoJapaneseboats,caughtdraggingbehind3smallboats,loadedwithmilitarygoods.Siazhentoolatetoescape,jumpedashoreJapancatchupwiththeboat,forcinghimtorowaboat.MeanwhilecaughtthemigrantsvillageZhangShun.Siazhenwassickforalongtime,图像的傅立叶变换与一维信号的傅立叶变换变换一样，有快速算法，具体参见参考书目，有关傅立叶变换的快速算法的程序不难找到。实际上，现在有实现傅立叶变换的芯片，可以实时实现傅立叶变换。3利用MATLAB软件实现数字图像傅立叶变换的程序：I=imread(‘原图像名.gif’);%读入原图像文件imshow(I);%显示原图像fftI=fft2(I);%二维离散傅立叶变换sfftI=fftshift(fftI);%直流分量移到频谱中心RR=real(sfftI);%取傅立叶变换的实部II=imag(sfftI);%取傅立叶变换的虚部A=sqrt(RR.^2+II.^2);%计算频谱幅值A=（A-min(min(A))）/(max(max(A))-min(min(A)))*225%归一化figure;%设定窗口imshow(A);%显示原图像的频谱三、实验步骤1．将图像内容读入内存；2．用Fourier变换算法，对图像作二维Fourier变换；3．将其幅度谱进行搬移，在图像中心显示；4．用Fourier系数的幅度进行Fourier反变换；5．用Fourier系数的相位进行Fourier反变换；6．比较4、5的结果，评价人眼对图像幅频特性和相频特性的敏感度。7．记录和整理实验报告。四、实验仪器1．计算机；2．MATLAB程序；3．移动式存储器（软盘、U盘等）。4．记录用的笔、纸。五、实验报告内容1．叙述实验过程；2．提交实验的原始图像和结果图像。Internet迅速发展无所不在以及诱人的低价位，的确令众多厂商开始采用这种办法，但Internet天生的开放性特点令人无所适从，安全性又成了问题，公司的机密数据一旦在Internet传输，若没有安全性保障，其后果可想而知。villagetemplesCentralOfficeeveryday,carryouttheirduties.CorrespondencerelatingtoeducationbytheChiefofthefirstsectionmarkedmydraftstatement.Workedafterafewmonths,I'vebeenburiedintheofficialprogram,veryrigidmonotonyofclericalcareer,flavourless.1939of7Augustbetween,County,andSec