对于倾斜的图像，可以通过矩阵转换将其进行矫正。
先计算出图像倾斜矩形的长宽，而后将矫正后的形状的矩形坐标确定，通过getPerspectiveTransform获取矫正前与矫正后坐标的变换矩阵，而后利用warpPerspective将图像进行变换
1 float dstSize1 = dist(Final_poly[i][0], Final_poly[i][1]); 2 float dstSize2 = dist(Final_poly[i][1], Final_poly[i][2]); 3 float dstSizeW, dstSizeH; 4 Point2f pts0[4], pts1[4]; 5 pts0[0].x = x1; pts0[0].y = y1; 6 pts0[1].x = x2; pts0[1].y = y2; 7 pts0[2].x = x3; pts0[2].y = y3; 8 pts0[3].x = x4; pts0[3].y = y4; 9 //cout<<pts0[0].x<<" "<<pts0[0].y<<" "<<pts0[1].x<<" "<<pts0[1].y<<" "<<pts0[2].x<<" "<<pts0[2].y<<" "<<pts0[3].x<<" "<<pts0[3].y<<endl; 10 //cout<<dstSize1<<" "<<dstSize2<<endl; 11 //if(dstSize1 > dstSize2 && fabs(Final_theta[i]) > 45.0) 12 if (fabs(Final_theta[i]) > 45.0) 13 { 14 dstSizeW = dstSize1; 15 dstSizeH = dstSize2; 16 pts1[0].x = dstSizeW; pts1[0].y = dstSizeH; 17 pts1[1].x = 0; pts1[1].y = dstSizeH; 18 pts1[2].x = 0; pts1[2].y = 0; 19 pts1[3].x = dstSizeW; pts1[3].y = 0; 20 } 21 //else if(dstSize1 < dstSize2 && fabs(Final_theta[i]) < 45.0) 22 else if (fabs(Final_theta[i]) <= 45.0) 23 { 24 dstSizeW = dstSize2; 25 dstSizeH = dstSize1; 26 pts1[0].x = 0; pts1[0].y = dstSizeH; 27 pts1[1].x = 0; pts1[1].y = 0; 28 pts1[2].x = dstSizeW; pts1[2].y = 0; 29 pts1[3].x = dstSizeW; pts1[3].y = dstSizeH; 30 } 31 Mat M_perspective = getPerspectiveTransform(pts0, pts1); 32 Mat img_perspective; 33 warpPerspective(image, img_perspective, M_perspective, Size(dstSizeW, dstSizeH), cv::INTER_CUBIC, cv::BORDER_CONSTANT);