利用OpenCV实现图像的仿射变换

利用OpenCV实现图像的仿射变换

仿射变换可以形象的表示成如下形式：一个平面内任意的平行四边形ABCD可以被仿射变换映射为另一个平行四边形A'B'C'D'，如果四边形的面积不等于0，仿射变换就被这两个平行四边形（其中的三个顶点）唯一的定义，这里注意确定一个平行四边形只需要三个顶点。我们可以把仿射变换想象成把一幅图像画到一个胶板上，在胶板的角上推或拉以得到不同的平行四边形。

下面的程序实现了对图像的仿射变换，还包括图像旋转、缩放这两个重要的子集。

#include <cv.h>

#include <highgui.h>

#include <stdio.h>

#include <iostream.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, *dstBak;

int TLx = 0, TLy = 0, TRx = 0, TRy = 0, DLx = 0, DLy = 0;

double angle = 40, scale = 0.8;

float delta = 0.01;

int PressKey;

char name[1][80];

if(!(src=cvLoadImage("C:/Users/jinxing/Desktop/Tests/test/Debug/lena.bmp",1)) )

{

printf("Input Error\n");

return -1;

}

srcTri[0].x = 0;// Top left

srcTri[0].y = 0;

srcTri[1].x = src->width-1;//Top right

srcTri[1].y = 0;

srcTri[2].x = 0;//Down left

srcTri[2].y = src->height-1;

dst = cvCloneImage(src);

srcBak = cvCloneImage(src);

cvCopy(src,srcBak);

dst->origin = src->origin;

cvZero(dst);

cvNamedWindow( "AffineTransform", 1 );

CvFont font = cvFont( 1, 1 );

while(1)

{

dstTri[0].x = srcBak->width*delta*(TLx%101);

dstTri[0].y = srcBak->height*delta*(TLy%101);

dstTri[1].x = srcBak->width-1 - srcBak->width*delta*(TRx%101);

dstTri[1].y = srcBak->height*delta*(TRy%101);

dstTri[2].x = srcBak->width*delta*(DLx%101);

dstTri[2].y = srcBak->height-1 - srcBak->height*delta*(DLy%101);

cvGetAffineTransform(srcTri,dstTri,warp_mat);

cvWarpAffine(srcBak,dst,warp_mat);

cvCopy(dst,src);

CvPoint2D32f center = cvPoint2D32f(src->width/2,src->height/2);

cv2DRotationMatrix(center,angle,scale,rot_mat);

cvWarpAffine(src,dst,rot_mat);

dstBak = cvCloneImage(dst);

cvCopy(dst,dstBak);

//--------------------------字符显示--------------------------------//

char buf[8];

char dspStr1[32] = {'|'};

char dspStr2[32] = {'|'};

char dspStr3[32] = {'|'};

char dspStr4[32] = {'|'};

memset(buf,'/0',sizeof(buf));

strcat(dspStr1,itoa(TLx%101,buf,10));

strcat(dspStr1,",");

strcat(dspStr1,itoa(TLy%101,buf,10));

strcat(dspStr1,"|TL");

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,itoa(TRx%101,buf,10));

strcat(dspStr3,",");

strcat(dspStr3,itoa(TRy%101,buf,10));

strcat(dspStr3,"|TR");

strcat(dspStr4,itoa(DLx%101,buf,10));

strcat(dspStr4,",");

strcat(dspStr4,itoa(DLy%101,buf,10));

strcat(dspStr4,"|DL");

cvPutText(dst,dspStr1,cvPoint(dst->width-120,20),&font,cvScalar(0,0xff));

cvPutText(dst,dspStr2,cvPoint(dst->width-180,80),&font,cvScalar(0,0xff));

cvPutText(dst,dspStr3,cvPoint(dst->width-120,40),&font,cvScalar(0,0xff));

cvPutText(dst,dspStr4,cvPoint(dst->width-120,60),&font,cvScalar(0,0xff));

//---------------------------------------------------------------------//

cvShowImage( "AffineTransform", dst );

PressKey = cvWaitKey();

printf("%c is pressed\n",PressKey);

switch(PressKey)

{

case '1':

TLx++;

break;

case 'q':

TLx--;

break;

case '2':

TLy++;

break;

case 'w':

TLy--;

break;

case '3':

TRx++;

break;

case 'e':

TRx--;

break;

case '4':

TRy++;

break;

case 'r':

TRy--;

break;

case '5':

DLx++;

break;

case 't':

DLx--;

break;

case '6':

DLy++;

break;

case 'y':

DLy--;

break;

case '7':

angle++;

break;

case 'u':

angle--;

break;

case '8':

scale+=0.01;

break;

case 'i':

scale-=0.01;

break;

case 27:

cvReleaseImage(&dst);

cvDestroyWindow("AffineTransform");

cvReleaseMat(&rot_mat);

cvReleaseMat(&warp_mat);

return 0;

case 's':

cout<<"Input the filename:"<<endl;

cin>>name[0];

cvSaveImage( name[0], dstBak );

cout<<name[0]<<" is saved."<<endl;

break;

default:

cout<<"Input Error."<<endl;

cout<<"Input 1 2 3 4 5 6 7 8 q w e r t y to change the coordinate."<<endl<<

"Input u and i to change the angle and scale."<<endl<<"Input s to save the image."<<endl

<<"Input the esc to quit."<<endl;

break;

}

}

cvDestroyWindow("AffineTransform");

cvReleaseImage(&dst);

cvReleaseMat(&rot_mat);

cvReleaseMat(&warp_mat);

return 0;

}

程序执行结果：