1、1MATLAB與數(shù)字信號(hào)處理圖象處理25 基于MATLAB的圖象處理n5.1 圖象運(yùn)算n5.2 圖象變換n5.3 圖象增強(qiáng)n5.4 圖象分割 n5.5 圖象分析35.1 圖象運(yùn)算n代數(shù)運(yùn)算、幾何運(yùn)算、鄰域操作和塊操作。代數(shù)運(yùn)算、幾何運(yùn)算、鄰域操作和塊操作。n1）代數(shù)運(yùn)算：）代數(shù)運(yùn)算：n 指對(duì)兩幅輸入圖象點(diǎn)對(duì)點(diǎn)的代數(shù)運(yùn)算。指對(duì)兩幅輸入圖象點(diǎn)對(duì)點(diǎn)的代數(shù)運(yùn)算。n絕對(duì)差值函數(shù)絕對(duì)差值函數(shù) z=imabsdiff(x,y)n I=imread( cameraman.tif );n J=uint8(filter2(fspecial(gaussian),I);n K=imabsdiff(I,J);n sub

2、plot(1,2,1);imshow(I,);n subplot(1,2,2);imshow(K,);4n顯示結(jié)果：5n圖象的疊加函數(shù)z=imadd(x,y)n I=imread( cameraman.tif );n J=imread(rice.tif);n K=imadd(I,J);n imshow(K,);6增加亮度n I=imread(rice.tif);n J=imadd(I,50);n subplot(2,2,1);imshow(I,);n subplot(2,2,2);imshow(J,);7n圖象的求補(bǔ)函數(shù)z=imcomplement(x)nI = imread(text.tif

3、);nJ = imcomplement(I);nsubplot(1,2,1);imshow(I,);nsubplot(1,2,2);imshow(J,)8n灰度圖象補(bǔ)運(yùn)算n I = imread(bonemarr.tif);n J = imcomplement(I); n subplot(1,2,1);imshow(I,);n subplot(1,2,2);imshow(J,)9n其它計(jì)算：n imdividen immultiplyn imsubtractn imlincomb10n2）幾何操作）幾何操作n改變圖象大?。焊淖儓D象大?。簓=imresize(x,m,method)I = imr

4、ead(circuit.tif); J = imresize(I,1.25); imshow(I);figure;imshow(J)11n圖象旋轉(zhuǎn)：圖象旋轉(zhuǎn)：y=imrotate(x,angle,method)nI = imread(circuit.tif);nJ = imrotate(I,-15,bilinear); nimshow(I);nfigure;nimshow(J)12n3）鄰域和塊操作）鄰域和塊操作n實(shí)現(xiàn)一個(gè)滑動(dòng)鄰域操作步驟：實(shí)現(xiàn)一個(gè)滑動(dòng)鄰域操作步驟：n（1）選擇一個(gè)單獨(dú)的像素。）選擇一個(gè)單獨(dú)的像素。n（2）確定該像素的滑動(dòng)鄰域。）確定該像素的滑動(dòng)鄰域。n（3）對(duì)鄰域中的像素值應(yīng)

5、用一個(gè)函數(shù)求值。）對(duì)鄰域中的像素值應(yīng)用一個(gè)函數(shù)求值。n（4）將結(jié)果作為對(duì)應(yīng)像素的值。）將結(jié)果作為對(duì)應(yīng)像素的值。n（5）對(duì)輸入圖象的每一個(gè)像素都重復(fù)上面四個(gè)步驟。）對(duì)輸入圖象的每一個(gè)像素都重復(fù)上面四個(gè)步驟。13n滑動(dòng)鄰域操作函數(shù)滑動(dòng)鄰域操作函數(shù)：n y=nlfilter(x,m n,fun，p1,p2,)nI=imread(tire.tif);nf=inline(max(x(:);nJ=nlfilter(I,3 3,f);nimshow(I);figure;imshow(J);14n塊操作函數(shù)塊操作函數(shù)：n y=blkproc(x,m n,fun，p1,p2,)nI=imread(cameram

6、an.tif);nf=dct;nJ=blkproc(I,8 8,f);nimagesc(J);15 I = imread(alumgrns.tif) fun = inline(std2(x)*ones(size(x); I2 = blkproc(I,8 8,fun); imshow(I) figure, imshow(I2,)16175.2 圖象變換n1）FFTn例：繪制一個(gè)二值圖象矩陣，將其傅立葉變換可視化nf=zeros(40,40);nf(5:24,13:17)=1;nsubplot(1,2,1);imshow(f);nF=fft2(f);nF2=log(abs(F);nsubplot(

7、1,2,2);nimshow(F2,-1 5);1819n圖象定位：圖象定位：nw=imread(text.tif);na=w(59:71,81:91);nimshow(w);figure;imshow(a);nC=ifft2(fft2(w).*fft2(rot90(a,2),256,256);nfigure;imshow(C,);nthresh=45;nfigure;imshow(Cthresh);2021n離散余弦變換：離散余弦變換：n 兩種方法：兩種方法：dct2 dctmtxn例：對(duì)圖象進(jìn)行DCT變換和反變換nRGB=imread(autumn.tif);nI=rgb2gray(RGB

8、);nsubplot(1,2,1);imshow(I);nJ=dct2(I);nsubplot(1,2,2);imshow(J);22n將上例中DCT變換后的矩陣中小于100的設(shè)為0，重構(gòu)圖象。nJ(abs(j)70;bw_210=steel210;imshow(steel);figure;subplot(1,2,1);imshow(bw_70);subplot(1,2,2);imshow(bw_210);67nr,c=find(bw_70=0);nbw_clean=bwselect(bw_210,c,r,8);nimshow(bw_clean);figure;nbw_skel=bwmorph(bw_clean,skel,6);nbw_pruned=bwmorph(bw_skel,spur,8);nsubplot(1,2,1);nimshow(bw_skel);nsubplot(1,2,2);nimshow(bw_pruned);68ngrain_boundaries=bw_pruned;nsubplot(1,2,1);imshow(grain_boundaries);nlabeled=bwlabel(grai