图像处理和分析技术基础试卷

1．根据所学过的图像处理和分析方法，设计一套算法流程来实现汽车牌照的定位和数字的识别（给出设计思想即可）。 答：要点:

Step 1：定位汽车牌照。

通过高通滤波，得到所有的边缘，对边缘细化（但要保持连通关系），找出所有封闭的边缘，对封闭边缘求多边形逼近。在逼近后的所有4边形中，找出尺寸与牌照大小相同的四边形。牌照被定位。 Step 2：识别数字。

对牌照区域中的细化后的图像对象进行识别（如前面所介绍的矩阵模糊识别法等）。

2、试设计一套算法来实现染色体（图像见下图）的统计与识别（给出算法思想即可）。

1.applylut 功能:

在二进制图像中利用lookup表进行边沿操作. 语法:

A = applylut(BW,lut) 举例

lut = makelut('sum(x(:)) == 4',2); BW1 = imread('text.tif'); BW2 = applylut(BW1,lut); imshow(BW1) figure, imshow(BW2) 相关命令: makelut 2.bestblk 功能:

确定进行块操作的块大小. 语法:

siz = bestblk([m n],k) [mb,nb] = bestblk([m n],k) 举例

siz = bestblk([640 800],72) siz = 64 50 相关命令: blkproc 3.blkproc 功能:

MATLAB高级应用——图形及影像处理 320 实现图像的显式块操作. 语法:

B = blkproc(A,[m n],fun)

B = blkproc(A,[m n],fun,P1,P2,...)

B = blkproc(A,[m n],[mborder nborder],fun,...) B = blkproc(A,'indexed',...) 举例

I = imread('alumgrns.tif');

I2 = blkproc(I,[8 8],'std2(x)*ones(size(x))'); imshow(I)

figure, imshow(I2,[]); 相关命令: colfilt, nlfilter,inline 4.brighten 功能:

增加或降低颜色映像表的亮度. 语法: brighten(beta)

newmap = brighten(beta) newmap = brighten(map,beta) brighten(fig,beta) 相关命令: imadjust, rgbplot 5.bwarea 功能:

计算二进制图像对象的面积. 语法:

total = bwarea(BW) 举例

BW = imread('circles.tif'); imshow(BW);

附录 MATLAB图像处理命令 321 bwarea(BW) ans = 15799 相关命令: bweuler, bwperim

6.bweuler. 功能:

计算二进制图像的欧拉数. 语法:

eul = bweuler(BW,n) 举例

BW = imread('circles.tif'); imshow(BW); bweuler(BW) ans = -2 相关命令:

bwmorph, bwperim 7.bwfill 功能:

填充二进制图像的背景色. 语法:

BW2 = bwfill(BW1,c,r,n) BW2 = bwfill(BW1,n) [BW2,idx] = bwfill(...) BW2 = bwfill(x,y,BW1,xi,yi,n) [x,y,BW2,idx,xi,yi] = bwfill(...) BW2 = bwfill(BW1,'holes',n) [BW2,idx] = bwfill(BW1,'holes',n) 举例

MATLAB高级应用——图形及影像处理 322 BW1 =[1 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 1 0 0 0 1 0 1 0 1 0 0 0 1 1 1 0 1 1 1 1 0 1 1 1 1 0 0 1 1 0 1 0 1 0 0 0 1 0 1 0 1 0 0 0 1 1 1 0]

BW2 = bwfill(BW1,3,3,8) BW2 = 1 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0

1 1 1 1 1 0 1 0 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 0 0 1 1 0 1 0 1 0 0 0 1 0 1 0 1 0 0 0 1 1 1 0 I = imread('blood1.tif'); BW3 = ~im2bw(I); BW4 = bwfill(BW3,'holes'); imshow(BW3) figure, imshow(BW4) 相关命令: bwselect, roifill 8.bwlabel 功能:

标注二进制图像中已连接的部分. 语法:

附录 MATLAB图像处理命令 323 L = bwlabel(BW,n) [L,num] = bwlabel(BW,n) 举例

BW = [1 1 1 0 0 0 0 0 1 1 1 0 1 1 0 0 1 1 1 0 1 1 0 0 1 1 1 0 0 0 1 0 1 1 1 0 0 0 1 0 1 1 1 0 0 0 1 0 1 1 1 0 0 1 1 0 1 1 1 0 0 0 0 0] L = bwlabel(BW,4) L =

1 1 1 0 0 0 0 0 1 1 1 0 2 2 0 0 1 1 1 0 2 2 0 0 1 1 1 0 0 0 3 0 1 1 1 0 0 0 3 0 1 1 1 0 0 0 3 0 1 1 1 0 0 3 3 0

1 1 1 0 0 0 0 0 [r,c] = find(L==2); rc = [r c] rc = 2 5 3 5 2 6 3 6 相关命令: bweuler, bwselect 9.bwmorph 功能:

提取二进制图像的轮廓. 语法:

BW2 = bwmorph(BW1,operation) BW2 = bwmorph(BW1,operation,n) 举例

BW1 = imread('circles.tif');

MATLAB高级应用——图形及影像处理 324 imshow(BW1);

BW2 = bwmorph(BW1,'remove'); BW3 = bwmorph(BW1,'skel',Inf); imshow(BW2) figure, imshow(BW3) 相关命令:

bweuler, bwperim, dilate, erode 10.bwperim 功能:

计算二进制图像中对象的周长. 语法:

BW2 = bwperim(BW1,n) 举例

BW1 = imread('circbw.tif'); BW2 = bwperim(BW1,8); imshow(BW1) figure, imshow(BW2)

附录 MATLAB图像处理命令 325 相关命令:

bwarea, bweuler, bwfill 11.bwselect 功能:

在二进制图像中选择对象. 语法:

BW2 = bwselect(BW1,c,r,n) BW2 = bwselect(BW1,n) [BW2,idx] = bwselect(...) 举例

BW1 = imread('text.tif'); c = [16 90 144]; r = [85 197 247];

BW2 = bwselect(BW1,c,r,4); imshow(BW1) figure, imshow(BW2) 相关命令:

bwfill, bwlabel, impixel, roipoly, roifill 12.cmpermute

MATLAB高级应用——图形及影像处理 326 功能:

调整颜色映像表中的颜色. 语法:

[Y,newmap] = cmpermute(X,map) [Y,newmap] = cmpermute(X,map,index) 举例

To order a colormap by luminance, use: ntsc = rgb2ntsc(map); [dum,index] = sort(ntsc(:,1));

[Y,newmap] = cmpermute(X,map,index); 相关命令: randperm 13.cmunique 功能:

查找颜色映像表中特定的颜色及相应的图像. 语法:

[Y,newmap] = cmunique(X,map) [Y,newmap] = cmunique(RGB) [Y,newmap] = cmunique(I)

相关命令: gray2ind, rgb2ind 14.col2im 功能:

将矩阵的列重新组织到块中. 语法:

A = col2im(B,[m n],[mm nn],block_type) A = col2im(B,[m n],[mm nn]) 相关命令:

blkproc, colfilt, im2col, nlfilter 15.colfilt 功能:

利用列相关函数进行边沿操作. 语法:

B = colfilt(A,[m n],block_type,fun)

B = colfilt(A,[m n],block_type,fun,P1,P2,...)

B = colfilt(A,[m n],[mblock nblock],block_type,fun,...) B = colfilt(A,'indexed',...) 附录 MATLAB图像处理命令 327 相关命令:

blkproc, col2im, im2col, nlfilter 16.colorbar 功能: 显示颜色条. 语法:

colorbar('vert') colorbar('horiz') colorbar(h) colorbar h = colorbar(...) 举例

I = imread('blood1.tif'); h = fspecial('log'); I2 = filter2(h,I);

imshow(I2,[]), colormap(jet(64)), colorbar 17.conv2 功能:

进行二维卷积操作.

语法:

C = conv2(A,B) C = conv2(hcol,hrow,A) C = conv2(...,shape) 举例 A = magic(5) A =

17 24 1 8 15 23 5 7 14 16 4 6 13 20 22

MATLAB高级应用——图形及影像处理 328 10 12 19 21 3 11 18 25 2 9

B = [1 2 1;0 2 0;3 1 3] B = 1 2 1 0 2 0 3 1 3

C = conv2(A,B) C =

17 58 66 34 32 38 15 23 85 88 35 67 76 16 55 149 117 163 159 135 67 79 78 160 161 187 129 51 23 82 153 199 205 108 75 30 68 135 168 91 84 9 33 65 126 85 104 15 27 相关命令: filter2 18.convmtx2 功能:

计算二维卷积矩阵. 语法:

T = convmtx2(H,m,n) T = convmtx2(H,[m n]) 相关命令: conv2 19.convn

功能: 计算n维卷积. 语法:

C = convn(A,B) C = convn(A,B,shape) 相关命令: conv2 20.corr2 功能:

计算两个矩阵的二维相关系数. 附录 MATLAB图像处理命令 329 语法: r = corr2(A,B) 相关命令: std2 21.dct2 功能:

进行二维离散余弦变换. 语法: B = dct2(A) B = dct2(A,m,n) B = dct2(A,[m n]) 举例

RGB = imread('autumn.tif'); I = rgb2gray(RGB); J = dct2(I);

imshow(log(abs(J)),[]), colormap(jet(64)), colorbar J(abs(J) < 10) = 0; K = idct2(J)/255; imshow(K) 相关命令: fft2, idct2, ifft2 22.dctmtx 功能:

MATLAB高级应用——图形及影像处理 330 计算离散余弦变换矩阵. 语法: D = dctmtx(n) 相关命令:

dct2 23.dilate 功能:

放大二进制图像. 语法:

BW2 = dilate(BW1,SE) BW2 = dilate(BW1,SE,alg) BW2 = dilate(BW1,SE,...,n) 举例

BW1 = imread('text.tif'); SE = ones(6,2); BW2 = dilate(BW1,SE); imshow(BW1) figure, imshow(BW2) 相关命令: bwmorph, erode 24.dither 功能:

通过抖动增加外观颜色分辨率,转换图像. 语法:

X = dither(RGB,map) BW = dither(I) 相关命令: rgb2ind 25.double

附录 MATLAB图像处理命令 331 功能:

转换数据为双精度型. 语法: B = double(A) 举例

A = imread('saturn.tif'); B = sqrt(double(A)); 相关命令:

im2double, im2uint, uint8 26.edge 功能:

识别强度图像中的边界.

语法:

BW = edge(I,'sobel') BW = edge(I,'sobel',thresh)

BW = edge(I,'sobel',thresh,direction) [BW,thresh] = edge(I,'sobel',...) BW = edge(I,'prewitt') BW = edge(I,'prewitt',thresh)

BW = edge(I,'prewitt',thresh,direction) [BW,thresh] = edge(I,'prewitt',...) BW = edge(I,'roberts') BW = edge(I,'roberts',thresh) [BW,thresh] = edge(I,'roberts',...) BW = edge(I,'log') BW = edge(I,'log',thresh) BW = edge(I,'log',thresh,sigma) [BW,threshold] = edge(I,'log',...) BW = edge(I,'zerocross',thresh,h) [BW,thresh] = edge(I,'zerocross',...) BW = edge(I,'canny') BW = edge(I,'canny',thresh) BW = edge(I,'canny',thresh,sigma) MATLAB高级应用——图形及影像处理 332 [BW,threshold] = edge(I,'canny',...) 举例

I = imread('rice.tif'); BW1 = edge(I,'prewitt'); BW2 = edge(I,'canny'); imshow(BW1); figure, imshow(BW2) 27.erode 功能:

弱化二进制图像的边界. 语法:

BW2 = erode(BW1,SE) BW2 = erode(BW1,SE,alg) BW2 = erode(BW1,SE,...,n) 举例

BW1 = imread('text.tif');

SE = ones(3,1); BW2 = erode(BW1,SE); imshow(BW1) figure, imshow(BW2) 相关命令: bwmorph, dilate

附录 MATLAB图像处理命令 333 28.fft2 功能:

进行二维快速傅里叶变换. 语法: B = fft2(A) B = fft2(A,m,n) 举例

load imdemos saturn2 imshow(saturn2) B = fftshift(fft2(saturn2));

imshow(log(abs(B)),[]), colormap(jet(64)), colorbar 相关命令:

dct2, fftshift, idct2, ifft2 29.fftn

功能: 进行n维快速傅里叶变换. 语法: B = fftn(A) B = fftn(A,siz) 相关命令: fft2, ifftn 30.fftshift

MATLAB高级应用——图形及影像处理 334 功能:

把快速傅里叶变换的DC组件移到光谱中心. 语法: B = fftshift(A) 举例 B = fftn(A); C = fftshift(B); 相关命令: fft2, fftn, ifftshift

31.filter2 功能:

进行二维线性过滤操作. 语法:

B = filter2(h,A) B = filter2(h,A,shape) 举例 A = magic(6) A =

35 1 6 26 19 24 3 32 7 21 23 25 31 9 2 22 27 20 8 28 33 17 10 15 30 5 34 12 14 16 4 36 29 13 18 11 h = fspecial('sobel') h = 1 2 1 0 0 0 -1 -2 -1

B = filter2(h,A,'valid') B = -8 4 4 -8 -23 -44 -5 40 -23 -50 1 40 -8 4 4 -8 相关命令: conv2, roifilt2 32.freqspace

附录 MATLAB图像处理命令 335 功能:

确定二维频率响应的频率空间. 语法:

[f1,f2] = freqspace(n) [f1,f2] = freqspace([m n]) [x1,y1] = freqspace(...,'meshgrid') f = freqspace(N) f = freqspace(N,'whole')

相关命令:

fsamp2, fwind1, fwind2 33.freqz2 功能:

计算二维频率响应. 语法:

[H,f1,f2] = freqz2(h,n1,n2) [H,f1,f2] = freqz2(h,[n2 n1]) [H,f1,f2] = freqz2(h,f1,f2) [H,f1,f2] = freqz2(h) [...] = freqz2(h,...,[dx dy]) [...] = freqz2(h,...,dx) freqz2(...) 举例

Hd = zeros(16,16); Hd(5:12,5:12) = 1; Hd(7:10,7:10) = 0; h = fwind1(Hd,bartlett(16)); colormap(jet(64))

freqz2(h,[32 32]); axis ([-1 1 -1 1 0 1]) 34.fsamp2

MATLAB高级应用——图形及影像处理 336 功能:

用频率采样法设计二维FIR过滤器. 语法:

h = fsamp2(Hd)

h = fsamp2(f1,f2,Hd,[m n]) 举例

[f1,f2] = freqspace(21,'meshgrid'); Hd = ones(21); r = sqrt(f1.^2 + f2.^2); Hd((r0.5)) = 0; colormap(jet(64)) mesh(f1,f2,Hd) 相关命令:

conv2, filter2, freqspace, ftrans2, fwind1, fwind2 35.fspecial 功能:

创建预定义过滤器. 语法:

h = fspecial(type)

h = fspecial(type,parameters) 举例

I = imread('saturn.tif'); h = fspecial('unsharp',0.5); I2 = filter2(h,I)/255; imshow(I) figure, imshow(I2) 相关命令:

conv2, edge, filter2, fsamp2, fwind1, fwind2 36.ftrans2 功能:

通过频率转换设计二维FIR过滤器. 语法:

附录 MATLAB图像处理命令 337 h = ftrans2(b,t) h = ftrans2(b) 举例

colormap(jet(64))

b = remez(10,[0 0.05 0.15 0.55 0.65 1],[0 0 1 1 0 0]); [H,w] = freqz(b,1,128,'whole'); plot(w/pi-1,fftshift(abs(H))) 相关命令:

conv2, filter2, fsamp2, fwind1, fwind2 37.fwind1 功能:

用一维窗口方法设计二维FIR过滤器. 语法:

h = fwind1(Hd,win) h = fwind1(Hd,win1,win2) h = fwind1(f1,f2,Hd,...) 举例

[f1,f2] = freqspace(21,'meshgrid'); Hd = ones(21); r = sqrt(f1.^2 + f2.^2); Hd((r0.5)) = 0;

colormap(jet(64)) mesh(f1,f2,Hd) 相关命令:

conv2, filter2, fsamp2, freqspace, ftrans2, fwind2 38.fwind2 功能:

用二维窗口方法设计二维FIR过滤器. 语法:

h = fwind2(Hd,win) h = fwind2(f1,f2,Hd,win) 举例

[f1,f2] = freqspace(21,'meshgrid'); Hd = ones(21); r = sqrt(f1.^2 + f2.^2); Hd((r0.5)) = 0; colormap(jet(64)) mesh(f1,f2,Hd)

MATLAB高级应用——图形及影像处理 338 相关命令:

conv2, filter2, fsamp2, freqspace, ftrans2, fwind1 39.getimage 功能:

从坐标轴取得图像数据. 语法:

A = getimage(h) [x,y,A] = getimage(h) [...,A,flag] = getimage(h) [...] = getimage 举例

imshow rice.tif I = getimage; 40.gray2ind 功能:

转换灰度图像为索引图像. 语法:

[X,map] = gray2ind(I,n) 相关命令: ind2gray

41.grayslice 功能:

从灰度图像创建索引图像. 语法:

X = grayslice(I,n) X = grayslice(I,v) 举例

I = imread('ngc4024m.tif'); X = grayslice(I,16); imshow(I)

figure, imshow(X,jet(16)) 附录 MATLAB图像处理命令 339 相关命令: gray2ind 42.histeq 功能:

用柱状图均等化增强对比. 语法:

J = histeq(I,hgram) J = histeq(I,n) [J,T] = histeq(I,...) 举例

I = imread('tire.tif'); J = histeq(I); imshow(I) figure, imshow(J) imhist(I,64) figure; imhist(J,64) 相关命令:

brighten, imadjust, imhist 43.hsv2rgb

功能: 转换HSV值为RGB颜色空间. 语法:

rgbmap = hsv2rgb(hsvmap) RGB = hsv2rgb(HSV) 相关命令:

MATLAB高级应用——图形及影像处理 340 rgb2hsv, rgbplot

44.idct2 功能:

计算二维离散反余弦变换. 语法: B = idct2(A) B = idct2(A,m,n) B = idct2(A,[m n]) 相关命令:

dct2, dctmtx, fft2, ifft2 45.ifft2 功能:

计算二维快速傅里叶反变换. 语法: B = ifft2(A) B = ifft2(A,m,n) 相关命令: fft2, fftshift, idct2 46.ifftn

功能: 计算n维快速傅里叶反变换. 语法: B = ifftn(A) B = ifftn(A,siz) 相关命令: fft2, fftn, ifft2 47.sim2bw 功能:

转换图像为二进制图像. 语法:

BW = im2bw(I,level) BW = im2bw(X,map,level) BW = im2bw(RGB,level) 举例 load trees

BW = im2bw(X,map,0.4); imshow(X,map)

附录 MATLAB图像处理命令 341 figure, imshow(BW) 相关命令:

ind2gray, rgb2gray 48.im2col 功能:

重调图像块为列. 语法:

B = im2col(A,[m n],block_type) B = im2col(A,[m n]) B = im2col(A,'indexed',...) 相关命令:

blkproc, col2im, colfilt, nlfilter 49.im2double 功能:

转换图像矩阵为双精度型. 语法:

I2 = im2double(I1) RGB2 = im2double(RGB1) BW2 = im2double(BW1) X2 = im2double(X1,'indexed') 相关命令:

double, im2uint8, uint8 50.im2uint8 功能:

转换图像阵列为8位无符号整型. 语法:

I2 = im2uint8(I1) RGB2 = im2uint8(RGB1) BW2 = im2uint8(BW1) X2 = im2uint8(X1,'indexed')

MATLAB高级应用——图形及影像处理 342 相关命令:

im2uint16, double, im2double, uint8, imapprox, uint16 51.im2uint16 功能:

转换图像阵列为16位无符号整型. 语法:

I2 = im2uint16(I1) RGB2 = im2uint16(RGB1) X2 = im2uint16(X1,'indexed')

相关命令:

im2uint8, double, im2double, uint8, uint16, imapprox 52.imadjust 功能:

调整图像灰度值或颜色映像表. 语法:

J = imadjust(I,[low high],[bottom top],gamma)

newmap = imadjust(map,[low high],[bottom top],gamma) RGB2 = imadjust(RGB1,...) 举例

I = imread('pout.tif'); J = imadjust(I,[0.3 0.7],[]); imshow(I) figure, imshow(J) 相关命令: brighten, histeq 53.imapprox 功能:

对索引图像进行近似处理. 语法:

[Y,newmap] = imapprox(X,map,n) 附录 MATLAB图像处理命令 343 [Y,newmap] = imapprox(X,map,tol) Y = imapprox(X,map,newmap) [...] = imapprox(...,dither_option) 相关命令:

cmunique, dither, rgb2ind 54.imcontour 功能:

创建图像数据的轮廓图. 语法: imcontour(I,n) imcontour(I,v) imcontour(x,y,...) imcontour(...,LineSpec) [C,h] = imcontour(...) 举例

I = imread('ic.tif');

imcontour(I,3) 相关命令:

clabel, contour, LineSpec 55.imcrop 功能: 剪切图像. 语法: I2 = imcrop(I) X2 = imcrop(X,map) RGB2 = imcrop(RGB) I2 = imcrop(I,rect) X2 = imcrop(X,map,rect) RGB2 = imcrop(RGB,rect)

MATLAB高级应用——图形及影像处理 344 [...] = imcrop(x,y,...) [A,rect] = imcrop(...) [x,y,A,rect] = imcrop(...) 举例

I = imread('ic.tif');

I2 = imcrop(I,[60 40 100 90]); imshow(I) figure, imshow(I2) 相关命令: zoom 56.imfeature 功能:

计算图像区域的特征尺寸. 语法:

stats = imfeature(L,measurements) stats = imfeature(L,measurements,n) 举例

BW = imread('text.tif'); L = bwlabel(BW); stats = imfeature(L,'all'); stats(23) ans = Area: 89

Centroid: [95.6742 192.9775]

BoundingBox: [87.5000 184.5000 16 15] MajorAxisLength: 19.9127 MinorAxisLength: 14.2953 Eccentricity: 0.6961 Orientation: 9.0845 ConvexHull: [28x2 double] 附录 MATLAB图像处理命令 345 ConvexImage: [15x16 uint8 ] ConvexArea: 205 Image: [15x16 uint8 ] FilledImage: [15x16 uint8 ] FilledArea: 122 EulerNumber: 0 Extrema: [ 8x2 double] EquivDiameter: 10.6451 Solidity: 0.4341 Extent: 0.3708 PixelList: [89x2 double] 相关命令: bwlabel 57.imfinfo 功能:

返回图形文件信息. 语法:

info = imfinfo(filename,fmt) info = imfinfo(filename) 举例

info = imfinfo('canoe.tif') info =

Filename:'canoe.tif'

FileModDate: '25-Oct-1996 22:10:39' FileSize: 69708 Format: 'tif' FormatVersion: [] Width: 346 Height: 207 BitDepth: 8

ColorType: 'indexed'

FormatSignature: [73 73 42 0] ByteOrder: 'little-endian' NewSubfileType: 0 BitsPerSample: 8 Compression: 'PackBits'

PhotometricInterpretation: 'RGB Palette' MATLAB高级应用——图形及影像处理 346 StripOffsets: [ 9x1 double] SamplesPerPixel: 1 RowsPerStrip: 23

StripByteCounts: [ 9x1 double] XResolution: 72 YResolution: 72 ResolutionUnit: 'Inch' Colormap: [256x3 double] PlanarConfiguration: 'Chunky' TileWidth: [] TileLength: [] TileOffsets: [] TileByteCounts: [] Orientation: 1 FillOrder: 1

GrayResponseUnit: 0.0100 MaxSampleValue: 255 MinSampleValue: 0 Thresholding: 1 相关命令: imread, imwrite 58.imhist 功能:

显示图像数据的柱状图. 语法: imhist(I,n) imhist(X,map) [counts,x] = imhist(...) 举例

I = imread('pout.tif'); imhist(I)

附录 MATLAB图像处理命令 347 相关命令: histeq 59.immovie 功能:

创建多帧索引图的电影动画. 语法:

mov = immovie(X,map) 举例 load mri

mov = immovie(D,map); 相关命令: montage 60.imnoise 功能:

增加图像的渲染效果. 语法:

J = imnoise(I,type)

J = imnoise(I,type,parameters) 举例

I = imread('eight.tif');

J = imnoise(I,'salt & pepper',0.02); imshow(I) figure, imshow(J) 相关命令: rand 61.impixel 功能:

确定像素颜色值. 语法:

MATLAB高级应用——图形及影像处理 348 P = impixel(I) P = impixel(X,map) P = impixel(RGB) P = impixel(I,c,r) P = impixel(X,map,c,r) P = impixel(RGB,c,r) [c,r,P] = impixel(...)

P = impixel(x,y,I,xi,yi) P = impixel(x,y,X,map,xi,yi) P = impixel(x,y,RGB,xi,yi) [xi,yi,P] = impixel(x,y,...) 举例

RGB = imread('flowers.tif'); c = [12 146 410]; r = [104 156 129]; pixels = impixel(RGB,c,r) pixels = 61 59 101 253 240 0 237 37 44 相关命令: improfile, pixval 62.improfile 功能:

沿线段计算剖面图的像素值. 语法: c = improfile c = improfile(n) c = improfile(I,xi,yi) c = improfile(I,xi,yi,n) [cx,cy,c] = improfile(...) [cx,cy,c,xi,yi] = improfile(...) [...] = improfile(x,y,I,xi,yi) [...] = improfile(x,y,I,xi,yi,n) 附录 MATLAB图像处理命令 349 [...] = improfile(...,method) 举例

I = imread('alumgrns.tif'); x = [35 338 346 103]; y = [253 250 17 148]; improfile(I,x,y), grid on 相关命令: impixel, pixval 63.imread 功能:

从图形文件中读取图像. 语法:

A = imread(filename,fmt) [X,map] = imread(filename,fmt) [...] = imread(filename) [...] = imread(...,idx) (TIFF only) [...] = imread(...,ref) (HDF only)

[...] = imread(...,'BackgroundColor',BG) (PNG only) [A,map,alpha] = imread(...) (PNG only) 举例

[X,map] = imread('flowers.tif',6); info = imfinfo('skull.hdf');

[X,map] = imread('skull.hdf',info(4).Reference); bg = [255 0 0];

A = imread('image.png','BackgroundColor',bg); MATLAB高级应用——图形及影像处理 350 [A,map,alpha] = imread('image.png'); 相关命令:

imfinfo, imwrite,fread,double,uint8,uint16 64.imresize 功能: 改变图像大小. 语法:

B = imresize(A,m,method)

B = imresize(A,[mrows ncols],method) B = imresize(...,method,n) B = imresize(...,method,h) 65.imrotate 功能: 旋转图像. 语法:

B = imrotate(A,angle,method) B = imrotate(A,angle,method,'crop') 举例

I = imread('ic.tif');

J = imrotate(I,-4,'bilinear','crop'); imshow(I) figure, imshow(J)

相关命令: imcrop, imresize 66.imshow 功能: 显示图像. 语法:

附录 MATLAB图像处理命令 351 imshow(I,n) imshow(I,[low high]) imshow(BW) imshow(X,map) imshow(RGB)

imshow(...,display_option) imshow(x,y,A,...) imshow filename h = imshow(...) 相关命令:

getimage, imread, iptgetpref, iptsetpref, subimage, truesize, warp 67.imwrite 功能:

把图像写入图形文件中. 语法:

imwrite(A,filename,fmt) imwrite(X,map,filename,fmt) imwrite(...,filename)

imwrite(...,Param1,Val1,Param2,Val2...) 举例

imwrite(X,map,'flowers.hdf','Compression','none',... 'WriteMode','append') 相关命令: imfinfo, imread 68.ind2gray 功能:

把检索图像转化为灰度图像. 语法:

I = ind2gray(X,map) 举例 load trees

I = ind2gray(X,map); imshow(X,map) figure,imshow(I)

MATLAB高级应用——图形及影像处理 352 相关命令:

gray2ind, imshow, rgb2ntsc 69.ind2rgb 功能:

转化索引图像为RGB真彩图像. 语法:

RGB = ind2rgb(X,map) 相关命令: ind2gray, rgb2ind 70.iptgetpref 功能:

获取图像处理工具箱参数设置. 语法:

value = iptgetpref(prefname) 举例

value = iptgetpref('ImshowAxesVisible') value = off 相关命令: imshow, iptsetpref 71.iptsetpref 功能:

设置图像处理工具箱参数. 语法:

iptsetpref(prefname,value) 举例

iptsetpref('ImshowBorder','tight') 相关命令:

imshow, iptgetpref, truesize 72.iradon

附录 MATLAB图像处理命令 353 功能:

进行反Radon变换. 语法:

I = iradon(P,theta)

I = iradon(P,theta,interp,filter,d,n) [I,h] = iradon(...) 举例

P = phantom(128); R = radon(P,0:179);

I = iradon(R,0:179,'nearest','Hann'); imshow(P) figure, imshow(I) 相关命令: radon, phantom 73.isbw 功能:

判断是否为二进制图像. 语法: flag = isbw(A) 相关命令: isind, isgray, isrgb 74.isgray 功能:

判断是否为灰度图像. 语法:

flag = isgray(A) 相关命令: isbw, isind, isrgb 75.isind

MATLAB高级应用——图形及影像处理 354 功能:

判断是否为索引图像. 语法: flag = isind(A) 相关命令: isbw, isgray, isrgb 76.isrgb 功能:

判读是否为RGB真彩图像. 语法: flag = isrgb(A)

相关命令: isbw, isgray, isind 77.makelut 功能:

创建一个用于applylut函数的lookup表. 语法:

lut = makelut(fun,n)

lut = makelut(fun,n,P1,P2,...) 举例

f = inline('sum(x(:)) >= 2'); lut = makelut(f,2) lut = 0 0 0 1 0 1 1 1 0 1 1 1 1 1

附录 MATLAB图像处理命令 355 1 1 相关命令: applylut 78.mat2gray 功能:

转化矩阵为灰度图像. 语法:

I = mat2gray(A,[amin amax]) I = mat2gray(A) 举例

I = imread('rice.tif'); J = filter2(fspecial('sobel'),I); K = mat2gray(J); imshow(I) figure, imshow(K) 相关命令: gray2ind 79.mean2 功能:

计算矩阵元素的平均值. 语法: b = mean2(A) 相关命令: std2, mean, std 80.medfilt2 功能:

进行二维中值过滤. 语法:

MATLAB高级应用——图形及影像处理 356 B = medfilt2(A,[m n]) B = medfilt2(A)

B = medfilt2(A,'indexed',...) 举例

I = imread('eight.tif');

J = imnoise(I,'salt & pepper',0.02); K = medfilt2(J); imshow(J) figure, imshow(K) 相关命令:

filter2, ordfilt2, wiener2 81.montage 功能:

在矩形框中同时显示多幅图像. 语法: montage(I) montage(BW) montage(X,map) montage(RGB)

h = montage(...) 举例 load mri montage(D,map)

附录 MATLAB图像处理命令 357 相关命令: immovie 82.nlfilter 功能: 进行边沿操作. 语法:

B = nlfilter(A,[m n],fun)

B = nlfilter(A,[m n],fun,P1,P2,...) B = nlfilter(A,'indexed',...) 举例

B = nlfilter(A,[3 3],'median(x(:))'); 相关命令: blkproc, colfilt 83.ntsc2rgb

功能: 转换NTSC的值为RGB颜色空间. 语法:

rgbmap = ntsc2rgb(yiqmap) RGB = ntsc2rgb(YIQ) 相关命令:

rgb2ntsc, rgb2ind, ind2rgb, ind2gray 84.ordfilt2 功能:

进行二维统计顺序过滤. 语法:

B = ordfilt2(A,order,domain) B = ordfilt2(A,order,domain,S)

MATLAB高级应用——图形及影像处理 358 B = ordfilt2(...,padopt) 相关命令: medfilt2 85.phantom 功能:

产生一个头部幻影图像.

语法:

P = phantom(def,n) P = phantom(E,n) [P,E] = phantom(...) 举例

P = phantom('Modified Shepp-Logan',200); imshow(P) 相关命令: radon, iradon 86.pixval 功能:

显示图像像素信息. 语法: pixval on pixval off pixval

pixval(fig,option) 相关命令: impixel, improfile 87.qtdecomp 功能:

进行四叉树分解.

附录 MATLAB图像处理命令 359 语法:

S = qtdecomp(I)

S = qtdecomp(I,threshold) S = qtdecomp(I,threshold,mindim)

S = qtdecomp(I,threshold,[mindim maxdim]) S = qtdecomp(I,fun)

S = qtdecomp(I,fun,P1,P2,...) 举例

I = [1 1 1 1 2 3 6 6 1 1 2 1 4 5 6 8 1 1 1 1 10 15 7 7 1 1 1 1 20 25 7 7 20 22 20 22 1 2 3 4 20 22 22 20 5 6 7 8 20 22 20 20 9 10 11 12

22 22 20 20 13 14 15 16]; S = qtdecomp(I,5); full(S) ans = 4 0 0 0 2 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 2 0 0 0 0 0 1 1 0 0 4 0 0 0 2 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 0 0 0 0 0 0 0 0 0 相关命令: qtgetblk, qtsetblk 88.qtgetblk 功能:

获取四叉树分解中的块值. 语法:

[vals,r,c] = qtgetblk(I,S,dim)

MATLAB高级应用——图形及影像处理 360 [vals,idx] = qtgetblk(I,S,dim) 举例

[vals,r,c] = qtgetblk(I,S,4) vals(:,:,1) = 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 vals(:,:,2) = 20 22 20 22 20 22 22 20 20 22 20 20 22 22 20 20 r = 1 5 c = 1

1 相关命令:

qtdecomp, qtsetblk 89.qtsetblk 功能:

设置四叉树分解中的块值. 语法:

J = qtsetblk(I,S,dim,vals) 举例

newvals = cat(3,zeros(4),ones(4)); J = qtsetblk(I,S,4,newvals) J =

0 0 0 0 2 3 6 6 0 0 0 0 4 5 6 8 0 0 0 0 10 15 7 7

附录 MATLAB图像处理命令 361 0 0 0 0 20 25 7 7 1 1 1 1 1 2 3 4 1 1 1 1 5 6 7 8 1 1 1 1 9 10 11 12 1 1 1 1 13 14 15 16 相关命令:

qtdecomp, qtgetblk 90.radon

功能: 计算Radon变换. 语法:

R = radon(I,theta) R = radon(I,theta,n) [R,xp] = radon(...) 举例

iptsetpref('ImshowAxesVisible','on') I = zeros(100,100); I(25:75,25:75) = 1; theta = 0:180; [R,xp] = radon(I,theta);

imshow(theta,xp,R,[]), colormap(hot), colorbar 相关命令: iradon, phantom

91.rgb2gray

功能: 转换RGB图像或颜色映像表为灰度图像. 语法:

I = rgb2gray(RGB) newmap = rgb2gray(map) 相关命令:

MATLAB高级应用——图形及影像处理 362 ind2gray, ntsc2rgb, rgb2ind, rgb2ntsc 92.rgb2hsv

功能: 转化RGB值为HSV颜色空间. 语法:

hsvmap = rgb2hsv(rgbmap) HSV = rgb2hsv(RGB) 相关命令: hsv2rgb, rgbplot 93.rgb2ind

功能: 转化RGB图像为索引图像. 语法:

[X,map] = rgb2ind(RGB,tol) [X,map] = rgb2ind(RGB,n) X = rgb2ind(RGB,map) [...] = rgb2ind(...,dither_option) 举例

RGB = imread('flowers.tif'); [X,map] = rgb2ind(RGB,128); imshow(X,map) 相关命令:

cmunique, dither, imapprox, ind2rgb, rgb2gray 94.rgb2ntsc

功能: 转化RGB的值为NTSC颜色空间. 语法:

yiqmap = rgb2ntsc(rgbmap) YIQ = rgb2ntsc(RGB)

附录 MATLAB图像处理命令 363 相关命令:

ntsc2rgb, rgb2ind, ind2rgb, ind2gray 95.rgb2ycbcr

功能: 转化RGB的值为YcbCr颜色空间.

语法:

ycbcrmap = rgb2ycbcr(rgbmap) YCBCR = rgb2ycbcr(RGB) 相关命令:

ntsc2rgb, rgb2ntsc, ycbcr2rgb 96.rgbplot 功能:

划分颜色映像表. 语法: rgbplot(map) 举例 rgbplot(jet) 相关命令: colormap 97.roicolor 功能:

选择感兴趣的颜色区. 语法:

BW = roicolor(A,low,high) BW = roicolor(A,v) 举例

I = imread('rice.tif'); BW = roicolor(I,128,255); imshow(I);

MATLAB高级应用——图形及影像处理 364 figure, imshow(BW) 相关命令: roifilt2, roipoly 98.roifill 功能:

在图像的任意区域中进行平滑插补. 语法: J = roifill(I,c,r) J = roifill(I) J = roifill(I,BW) [J,BW] = roifill(...) J = roifill(x,y,I,xi,yi) [x,y,J,BW,xi,yi] = roifill(...)

举例

I = imread('eight.tif');

c = [222 272 300 270 221 194]; r = [21 21 75 121 121 75]; J = roifill(I,c,r); imshow(I) figure, imshow(J)

附录 MATLAB图像处理命令 365 相关命令: roifilt2, roipoly 99.roifilt2 功能: 过滤敏感区域. 语法:

J = roifilt2(h,I,BW) J = roifilt2(I,BW,fun)

J = roifilt2(I,BW,fun,P1,P2,...) 举例

h = fspecial('unsharp'); J = roifilt2(h,I,BW); imshow(J) 相关命令: filter2, roipoly 100.roipoly 功能:

选择一个敏感的多边形区域. 语法:

BW = roipoly(I,c,r) BW = roipoly(I) BW = roipoly(x,y,I,xi,yi) [BW,xi,yi] = roipoly(...) [x,y,BW,xi,yi] = roipoly(...) 举例

I = imread('eight.tif');

c = [222 272 300 270 221 194]; r = [21 21 75 121 121 75]; BW = roipoly(I,c,r); imshow(I)

MATLAB高级应用——图形及影像处理 366 figure, imshow(BW) 相关命令:

roifilt2, roicolor, roifill 101.std2 功能:

计算矩阵元素的标准偏移. 语法: b = std2(A) 相关命令: corr2, mean2 102.subimage 功能:

在一幅图中显示多个图像. 语法:

subimage(X,map) subimage(I) subimage(BW) subimage(RGB) subimage(x,y,...) h = subimage(...) 举例 load trees

[X2,map2] = imread('forest.tif'); subplot(1,2,1), subimage(X,map) subplot(1,2,2), subimage(X2,map2) 相关命令:

附录 MATLAB图像处理命令 367 103.truesize 功能:

调整图像显示尺寸. 语法:

truesize(fig,[mrows mcols]) truesize(fig) 相关命令:

imshow, iptsetpref, iptgetpref 104.uint8 功能:

转换数据为8位无符号整型. 语法: B = uint8(A) 举例 a = [1 3 5]; b = uint8(a); whos

Name Size Bytes Class a 1x3 24 doublearray b 1x3 3 uint8 array 相关命令:

double, im2double, im2uint8 105.uint16 功能:

转换数据为16位无符号整型. 语法: I = uint16(X)

MATLAB高级应用——图形及影像处理 368 举例 a = [1 3 5]; b = uint16(a); whos

Name Size Bytes Class a 1x3 24 double array b 1x3 6 uint16 array 相关命令:

double, datatypes, uint8, uint32, int8, int16, int32. 106.warp 功能:

将图像显示到纹理映射表面. 语法: warp(X,map) warp(I,n) warp(BW) warp(RGB) warp(z,...) warp(x,y,z,...) h = warp(...)

举例

[x,y,z] = cylinder; I = imread('testpat1.tif'); warp(x,y,z,I); 相关命令: imshow

附录 MATLAB图像处理命令 369 107.wiener2 功能:

进行二维适应性去噪过滤处理. 语法:

J = wiener2(I,[m n],noise) [J,noise] = wiener2(I,[m n]) 举例

I = imread('saturn.tif');

J = imnoise(I,'gaussian',0,0.005); K = wiener2(J,[5 5]); imshow(J) figure, imshow(K) 相关命令: filter2, medfilt2 108.ycbcr2rgb

功能: 转化YcbCr值为RGB颜色空间. 语法:

rgbmap = ycbcr2rgb(ycbcrmap) RGB = ycbcr2rgb(YCBCR) 相关命令:

ntsc2rgb, rgb2ntsc, rgb2ycbcr 109.zoom 功能: 缩放图像. 语法: zoom on zoom off zoom out

MATLAB高级应用——图形及影像处理 370 zoom reset zoom

zoom xon zoom yon zoom(factor) zoom(fig,option) 相关命令: imcrop

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