数字图像处理(双语)期中考试试卷答案.pdf

《数字图像处理(双语)期中考试试卷答案.pdf》由会员分享，可在线阅读，更多相关《数字图像处理(双语)期中考试试卷答案.pdf（5页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、考试试卷（答案）考试试卷（答案）试卷编号试卷编号:（)卷卷课程编号：课程名称：数字图像处理（双语）考试形式：课程编号：课程名称：数字图像处理（双语）考试形式：适用班级：姓名：学号：班级：适用班级：姓名：学号：班级：学院：信息工程学院专业学院：信息工程学院专业:电子系各专业考试日期：电子系各专业考试日期：题分题分得分得分一一2020二二2020三三2020四四2020五五2020六六0 0七七0 0八八0 0九九0 0十十0 0总分总分100100累累 分分 人人签签名名考生注意事项：1、本试卷共 5 页，请查看试卷中是否有缺页或破损.如有立即举手报告以便更换.2、考试结束后,考生不得将试卷、答

2、题纸和草稿纸带出考场。一、基础知识填空题(1,2 为单项选择，每空 3 分，3,4 为多项选择,每空 2 分，共20 分)，1 1、When you enter a dark room on a bright day,it takes some time to see wellenough,this is the visual process or visual phenomenon ofA.（Brightness adaptation.)B。（Brightness discrimination。）C.（Optical illusion。）D.(Simultaneous contrast.)2

3、、The visible spectrum consists of electromagnetic spectrum nearly in therange of wavelength:A.(10 400nm)B。（0。01 10 nm)C。(400 700 nm）D.(700 1500 nm)3、For V=1，the subsets S1 and S2areA.(mconnected)B。(8connected）C.（4-connected)D。(None of these 3）4、Two pixels pandqare at the locations shown in the figur

4、e,their Euclidean,city-block and chessboard distances are respectively:A。De=（)B.D4=（6）C.D8=（4）0001212765(p)34567得分得分评阅人评阅人（q)45673第 1 页 共 5页二、空域图像增强题 1（Image enhancement in the spatial domain)（20 分）Exponential of the form s=T（r)=255,0 r 255,with beingapositiveconstant,areusefulforconstructingsmoothg

5、ray-leveltransformation functions.(1)Start with this basic function and constructtransformation functions having the shapes shown in the above figures.(15255分）(2)What kind255of transformation does255the function of(a）approximatelyapproximatelycomplete for an input of a gray intensity image?(5分）(1)so

6、。得分得分评阅人评阅人so(a),can not be decided from the information givenby the figure（c)。We can specifywith an arbitrarypositive number,for example,the same as in(a)or in(b）.(2）The transform function of(a)is likely to complete the reverse transform.(c)(a)(b)第 2 页 共 5页三、空域图像增强题 2（Image enhancement in the spati

7、al domain）（20分）The White bars in the test pattern shown are 7 pixels wide and 210 pixelshigh。The separator between bars is 17 pixels.What would this image looklike after application of得分得分评阅人评阅人1.A 33 median filter？2.A 77 median filter?3.A 99 median filter？4.A 1515 median filter?（Note:in your answer

8、,quantitative analysis is expected。)AnswerAnswer：(a)The separator between bars is 17 pixels wide 15，so none of the4 filters can remove any black pixels。We can treat all black pixels asbackground。1.Applying a 3 3 median filter removes the 1 pixel at the top left，topright，bottom left and bottom right

9、locations of each bar,as shown in(a),which is an amplified corner of the filtered image。2.Applying a 77 median filter remove 6 pixels(b)located at the top left,the top right，the bottom left,the bottom right of each bar，as shown in（b)，whichis an amplified corner of the median filtered image。(b)011111

10、0000100033111111177011111101111111011111103.Applying a 99 median filter remove 10 pixelslocated at the top left,the top right,the bottom left，(a)the bottom right of each bar，as shown in（c）.which is(c)an amplified corner of the median filtered image000000099001110001111104。This time all bars are disa

11、ppeared。三、频域图像增强题(Image enhancement in the frequency domain）(20分）We know that a lowpass filter transfer function has the relation with thatof the highpass filter第 3 页 共 5页四、频域图像增强题 1（Image enhancement in Freq。Domain 1)(20分）Given a continuous function f（t）=cos（2nt)，(1)Its period T=？得分得分评阅人评阅人(2)Its f

12、requency F=？(3)Its Fourier transform F F（j）=？(4)The Nyquist rate fs=?(5)If it is sampled with a rate higher than fs,whats the sampling function？What do the sampled function and itsFourier transform like like?(6)If it is sampled with a rate lower than fs，answer the same problem as(5）。(7)If it is samp

13、led with the Nyquist rate at the instants t=0，T,2T,，answer the same problem as得分得分评阅人评阅人(5）.Answer:Answer:(1)The period T=1/n。(2)The frequency F=n.(3)F F(j)=(a)(a)The period is such that 2nt=2,or t=1/n。（b b）The frequency is 1 divided by the period，or n。The continuous Fourier transformof the given si

14、ne wave looks as in Fig.P4.4(a）(see Problem 4.3),and thetransform of the sampled data(showing a few periods)has the general form illustratedin Fig。P4。4(b)（the dashed box is an ideal filter that would allow reconstructionif the sine function were sampled,with the sampling theorem beingsatisfied)。(c)(

15、c)The Nyquist sampling rate is exactly twice the highest frequency，or 2n.Thatis,(1/T)=2n，or T=1/2n。Taking samples at t=T,2T,.。wouldyield the sampled function sin（2nT）whose values are all 0s because T=54CHAPTER 4。PROBLEM SOLUTIONS n nF（）Figure P4Figure P4。4 41/2n and n is an integer.In terms of Fig.P

16、4。4（b）,we see that when T=1/2nall the positive and negative impulses would coincide,thus canceling each otherand giving a result of 0 for the sampled data。(d(d）When the sampling rate is less than the Nyquist rate,we can have a situationsuch as the one illustrated in Fig.P4.4（c）,which is the sum of t

17、wo sine wavesin this case.For some values of sampling，the sum of the two sines combine toform a single sine wave and a plot of the samples would appear as in Fig.4.8 ofthe book.Other values would result in functions whose samples can describeany shape obtainable by sampling the sum of two sines。第 4

18、页 共 5页五、频域图像增强题 2(Image enhancement in Freq。Domain 2)（20 分）In a group of images there are（1）somebright and isolated dots we are not interested得分得分评阅人评阅人in,(2)not sufficient resolutions,(3)notsufficient contrast and(4)the average graylevel was changed whereas the correct DCvalue should be V。Please pr

19、opose solutions or processing steps respectively for theseobjectives by using the methods introduced in Chapter 3 or Chapter 4 of thetextbook in our bilingual course Digital Image Processing。Answer：(1）Performamedian filtering operation,because the median filter isgood at eliminating the isolated noi

20、ses。(2）Follow(1）by highfrequency emphasis.（3）Histogramequalize this result or some piecewise linearstretch filters。（4)Compute the average gray level，K0.Add the quantity（VK0)to all pixels.If the blank space is not enoughIf the blank space is not enough，you can write your answer on the reverse of the pageyou can write your answer on the reverse of the page。第 5 页 共 5页