matlab练习程序(透视变换)
close all; clc; H=1; %索引pix中第一个元素,即高度 W=2; %索引pix中第二个元素,即宽度 left_right=0.3; %抬起左边或右边时值为0-1之间,不抬起时为0 up_down=0; %抬起上边或下边时值为0-1之间,不抬起时为0 img=imread('lena.jpg'); %这里v为原图像的高度,u为原图像的宽度 imshow(img); %这里y为变换后图像的高度,x为变换后图像的宽度 %img=flipud(img); %注释掉为抬起下边,没注释掉为抬起上边 %img=fliplr(img); %注释掉为抬起右边,没注释掉为抬起左边 [v u]=size(img); a=1;b=up_down;c=0; d=left_right;e=1;f=0; g=up_down/v;h=left_right/u;i=1; rot=[a b c;d e f;g h i]; pix1=[1 1 1]*rot./(g+h+i); %变换后图像左上点的坐标 pix2=[1 u 1]*rot./(g*v+h+i); %变换后图像右上点的坐标 pix3=[v 1 1]*rot./(g+h*u+i); %变换后图像左下点的坐标 pix4=[v u 1]*rot./(g*v+h*u+i); %变换后图像右下点的坐标 height=round(max([abs(pix1(H)-pix3(H))+0.5 abs(pix2(H)-pix3(H))+0.5 ... abs(pix1(H)-pix4(H))+0.5 abs(pix2(H)-pix4(H))+0.5])); %变换后图像的高度 width=round(max([abs(pix1(W)-pix2(W))+0.5 abs(pix3(W)-pix2(W))+0.5 ... abs(pix1(W)-pix4(W))+0.5 abs(pix3(W)-pix4(W))+0.5])); %变换后图像的宽度 imgn=zeros(height,width); delta_y=abs(min([pix1(H)-0.5 pix2(H)-0.5 pix3(H)-0.5 pix4(H)-0.5])); %取得y方向的负轴超出的偏移量 delta_x=abs(min([pix1(W)-0.5 pix2(W)-0.5 pix3(W)-0.5 pix4(W)-0.5])); %取得x方向的负轴超出的偏移量 for y=1-floor(delta_y):height-floor(delta_y) for x=1-floor(delta_x):width-floor(delta_x) pix=[y x 1]/rot*(g*y+h*x+i); %用变换后图像的点的坐标去寻找原图像点的坐标, %否则有些变换后的图像的像素点无法完全填充 if pix(H)>=0.5 && pix(W)>=0.5 && pix(H)<=v && pix(W)<=u imgn(y+floor(delta_y),x+floor(delta_x))=img(round(pix(H)),round(pix(W))); end end end figure,imshow(uint8(imgn)); %%二次变换,暂时只想起来这种笨方法,一次变换好像没法进行透视变换 img=imgn; [v u]=size(img); a=1;b=-b/2;c=0; d=-d/2;e=1;f=0; g=0;h=0;i=1; rot=[a b c;d e f;g h i]; pix1=[1 1 1]*rot./(g+h+i); %变换后图像左上点的坐标 pix2=[1 u 1]*rot./(g*v+h+i); %变换后图像右上点的坐标 pix3=[v 1 1]*rot./(g+h*u+i); %变换后图像左下点的坐标 pix4=[v u 1]*rot./(g*v+h*u+i); %变换后图像右下点的坐标 height=round(max([abs(pix1(H)-pix3(H))+0.5 abs(pix2(H)-pix3(H))+0.5 ... abs(pix1(H)-pix4(H))+0.5 abs(pix2(H)-pix4(H))+0.5])); %变换后图像的高度 width=round(max([abs(pix1(W)-pix2(W))+0.5 abs(pix3(W)-pix2(W))+0.5 ... abs(pix1(W)-pix4(W))+0.5 abs(pix3(W)-pix4(W))+0.5])); %变换后图像的宽度 imgn=zeros(height,width); delta_y=abs(min([pix1(H)-0.5 pix2(H)-0.5 pix3(H)-0.5 pix4(H)-0.5])); %取得y方向的负轴超出的偏移量 delta_x=abs(min([pix1(W)-0.5 pix2(W)-0.5 pix3(W)-0.5 pix4(W)-0.5])); %取得x方向的负轴超出的偏移量 for y=1-floor(delta_y):height-floor(delta_y) for x=1-floor(delta_x):width-floor(delta_x) pix=[y x 1]/rot*(g*y+h*x+i); %用变换后图像的点的坐标去寻找原图像点的坐标, %否则有些变换后的图像的像素点无法完全填充 if pix(H)>=0.5 && pix(W)>=0.5 && pix(H)<=v && pix(W)<=u imgn(y+floor(delta_y),x+floor(delta_x))=img(round(pix(H)),round(pix(W))); end end end %imgn=flipud(imgn); %注释掉为抬起下边,没注释掉为抬起上边 %imgn=fliplr(imgn); %注释掉为抬起右边,没注释掉为抬起左边 figure,imshow(uint8(imgn));
图片福利:
注:更好的实现在这里
参考网址:
1.http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/EPSRC_SSAZ/epsrc_ssaz.html
2.http://alumni.media.mit.edu/~cwren/interpolator/
3.http://www.robots.ox.ac.uk/~vgg/presentations/bmvc97/criminispaper/