opencv仿射变换与透视变换

基本上就是learning opencv一书第4章，练习7的答案了。

先来个自己写的透视变换代码：

//透视变换#include <cv.h>#include <highgui.h>#include <math.h>int main(int argc,char** argv){CvPoint2D32f srcQuad[4],dstQuad[4];CvMat* warp_matrix = cvCreateMat(3,3,CV_32FC1);IplImage *src,*dst;src=cvLoadImage("../lena.jpg",1);if(!src)return -1;cvNamedWindow("Perspective_warp",1);int pressKey;int df1(1),df2(1),df3(1),df4(1),df5(1),df6(1),df7(1),df8(1);df1 = 5;df2 = 33;df3 = 90;df4 = 25;df5 = 20;df6 = 70;df7 = 80;df8 = 90;//df1 = df2 = df3 = df4 = df5 = df6 = df7 = df8 = 0;dst = cvCloneImage(src);dst->origin = src->origin;cvZero(dst);srcQuad[0].x = 0;srcQuad[0].y = 0;srcQuad[1].x = src->width - 1;srcQuad[1].y = 0;srcQuad[2].x = 0;srcQuad[2].y = src->height - 1;srcQuad[3].x = src->width - 1;srcQuad[3].y = src->height - 1;float delta=0.01;while(1){//dstQuad[0].x = src->width*delta*(df1%101);//dstQuad[0].y = src->height*delta*(df2%101);//dstQuad[1].x = src->width - 1+src->width*delta*(df3%101);//dstQuad[1].y = src->height*delta*(df4%101);//dstQuad[2].x = src->width*delta*(df5%101);//dstQuad[2].y = src->height - 1+src->height*delta*(df6%101);//dstQuad[3].x = src->width - 1+src->width*delta*(df7%101);//dstQuad[3].y = src->height - 1+src->height*delta*(df8%101);dstQuad[0].x = src->width*delta*abs(df1%101);dstQuad[0].y = src->height*delta*abs(df2%101);dstQuad[1].x = src->width*delta*abs(df3%101);dstQuad[1].y = src->height*delta*abs(df4%101);dstQuad[2].x = src->width*delta*abs(df5%101);dstQuad[2].y = src->height*delta*abs(df6%101);dstQuad[3].x = src->width*delta*abs(df7%101);dstQuad[3].y = src->height*delta*abs(df8%101);cvGetPerspectiveTransform(srcQuad,dstQuad,warp_matrix);cvWarpPerspective(src,dst,warp_matrix);//--------------------------字符显示-----------------------------------------CvFont font = cvFont(1,1);char buf[8];char dspStr1[32] = {'/0'};//char dspStr2[32] = {'/0'};//char dspStr3[32] = {'/0'};//memset(buf,'/0',sizeof(buf));strcat(dspStr1,"|");strcat(dspStr1,itoa(abs(df6%101),buf,10));strcat(dspStr1,",");strcat(dspStr1,itoa(abs(df7%101),buf,10));strcat(dspStr1,",");strcat(dspStr1,itoa(abs(df8%101),buf,10));strcat(dspStr1,"|");strcat(dspStr2,"|");strcat(dspStr2,itoa(abs(df4%101),buf,10));strcat(dspStr2,",00,");strcat(dspStr2,itoa(abs(df5%101),buf,10));strcat(dspStr2,"|");//「」┌└┘┐|strcat(dspStr3,"|");strcat(dspStr3,itoa(abs(df1%101),buf,10));strcat(dspStr3,",");strcat(dspStr3,itoa(abs(df2%101),buf,10));strcat(dspStr3,",");strcat(dspStr3,itoa(abs(df3%101),buf,10));strcat(dspStr3,"|");cvPutText(dst,dspStr1,cvPoint(dst->width-120,20),&font,cvScalar(0,0xff));cvPutText(dst,dspStr2,cvPoint(dst->width-120,40),&font,cvScalar(0,0xff));cvPutText(dst,dspStr3,cvPoint(dst->width-120,60),&font,cvScalar(0,0xff));//-------------------------------------------------------------------cvShowImage("Perspective_warp",dst);pressKey = cvWaitKey();printf("%x pressed/n",pressKey);switch(pressKey){case '1':df1++;break;case 0x230000:df1--;break;case '2':df2++;break;case 0x280000:df2--;break;case '3':df3++;break;case 0x220000:df3--;break;case '4':df4++;break;case 0x250000:df4--;break;case '6':df5++;break;case 0x270000:df5--;break;case '7':df6++;break;case 0x240000:df6--;break;case '8':df7++;break;case 0x260000:df7--;break;case '9':df8++;break;case 0x210000:df8--;break;case 27:cvReleaseImage(&dst);cvDestroyWindow("Perspective_warp");cvReleaseMat(&warp_matrix);return 0;default:break;}}return 0;}

这个程序的运行效果，是比较容易分析的，就是变换一张图片的四个角的位置后，引起图像的相应变化，而每个角就是二维平面的一个点具有x和y属性，4个点的x，y间接保存到df1到df8变量中。

      注意cvCloneImage函数和cvCopyImage函数的区别，前来可用来分配内存，后者不负责内存分配，只负责值的传递。这个代码不包含图像的放大、缩小、旋转功能，不过如果愿意的话，完全可以用例子中的函数自己写这些功能，因为放大、缩小、旋转图像不过是任意变换图像四个角的特例。

 

     再来个自己写的仿射变换代码：

//仿射变换#include <cv.h>#include <highgui.h>int main(int argc,char** argv){CvPoint2D32f srcTri[3],dstTri[3];CvMat* rot_mat = cvCreateMat(2,3,CV_32FC1);CvMat* warp_mat = cvCreateMat(2,3,CV_32FC1);IplImage *src,*dst, *srcBak;//int df1(0),df2(33),df3(85),df4(25),df5(15),df6(70);int df1(0),df2(0),df3(0),df4(0),df5(0),df6(0);double angle(-50.0),scale(0.6);float delta = 0.01;int pressKey;if(!(src=cvLoadImage("../ac.jpg",1)) ){return -1;}srcTri[0].x = 0;srcTri[0].y = 0;srcTri[1].x = src->width-1;srcTri[1].y = 0;srcTri[2].x = 0;srcTri[2].y = src->height-1;dst = cvCloneImage(src);srcBak = cvCloneImage(src);cvCopy(src,srcBak);dst->origin = src->origin;cvZero(dst);cvNamedWindow("at",1);CvFont font = cvFont(1,1);while(1){dstTri[0].x = srcBak->width*delta*(df1%101);dstTri[0].y = srcBak->height*delta*(df2%101);dstTri[1].x = src->width-1 + srcBak->width*delta*(df3%101);dstTri[1].y = srcBak->height*delta*(df4%101);dstTri[2].x = srcBak->width*delta*(df5%101);dstTri[2].y = src->height-1 + srcBak->height*delta*(df6%101);cvGetAffineTransform(srcTri,dstTri,warp_mat);cvWarpAffine(srcBak,dst,warp_mat);cvCopy(dst,src);//compute rotation matrixCvPoint2D32f center = cvPoint2D32f(src->width/2,src->height/2);cv2DRotationMatrix(center,angle,scale,rot_mat);//do the transformationcvWarpAffine(src,dst,rot_mat);//--------------------------字符显示-----------------------------------------char buf[8];char dspStr1[32] = {'/0'};//char dspStr2[32] = {'/0'};//char dspStr3[32] = {'/0'};//memset(buf,'/0',sizeof(buf));strcat(dspStr1,"|");strcat(dspStr1,itoa(df4%101,buf,10));strcat(dspStr1,",");strcat(dspStr1,itoa(df5%101,buf,10));strcat(dspStr1,",");strcat(dspStr1,itoa(df6%101,buf,10));strcat(dspStr1,"|");strcat(dspStr2,"|angle=");strcat(dspStr2,itoa(int(angle),buf,10));strcat(dspStr2,",scale=");strcat(dspStr2,itoa(int(scale*100),buf,10));strcat(dspStr2,"%|");//「」┌└┘┐|strcat(dspStr3,"|");strcat(dspStr3,itoa(df1%101,buf,10));strcat(dspStr3,",");strcat(dspStr3,itoa(df2%101,buf,10));strcat(dspStr3,",");strcat(dspStr3,itoa(df3%101,buf,10));strcat(dspStr3,"|");cvPutText(dst,dspStr1,cvPoint(dst->width-120,20),&font,cvScalar(0,0xff));cvPutText(dst,dspStr2,cvPoint(dst->width-210,40),&font,cvScalar(0,0xff));cvPutText(dst,dspStr3,cvPoint(dst->width-120,60),&font,cvScalar(0,0xff));//-------------------------------------------------------------------------------------cvShowImage("at",dst);pressKey = cvWaitKey();//printf("src->width:%d/n",src->width);printf("%c pressed/n",pressKey);switch(pressKey){case '1':df1++;break;case 0x230000:df1--;break;case '2':df2++;break;case 0x280000:df2--;break;case '3':df3++;break;case 0x220000:df3--;break;case '4'://旋转角度angle++;break;case 0x250000:angle--;break;case '6'://缩放scale+=0.01;break;case 0x270000:scale-=0.01;break;case '7':df4++;break;case 0x240000:df4--;break;case '8':df5++;break;case 0x260000:df5--;break;case '9':df6++;break;case 0x210000:df6--;break;case 27:cvReleaseImage(&dst);cvDestroyWindow("at");cvReleaseMat(&rot_mat);cvReleaseMat(&warp_mat);return 0;default:break;}}cvReleaseImage(&dst);cvReleaseMat(&rot_mat);cvReleaseMat(&warp_mat);return 0;}

      这个程序中加入图片的放大、缩小、旋转功能，另外仿射变换也是透视变换的一个特例，因为仿射变换过程中图像始终是平行四边形的。所以要确定仿射变换的目标图像，只需要三个点的坐标，因为三个点可以确定一个平行四边形，比透视变换少一个点的坐标。