MATLAB图像处理函数汇总2

MATLAB图像处理数汇总 （二） MATLAB图像处理函数汇总 （二） 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: 计算离散余弦变换矩阵. MATLAB高级应用——图形及影像处理 330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: rgb2hsv, rgbplot MATLAB高级应用——图形及影像处理 340 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. 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) [vals,idx] = qtgetblk(I,S,dim) MATLAB高级应用——图形及影像处理 360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: ind2gray, ntsc2rgb, rgb2ind, rgb2ntsc MATLAB高级应用——图形及影像处理 362 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