图像切边

这里采用第一种方法
待处理得图
  1 #include <opencv2/opencv.hpp>
  2 #include <iostream>
  3 #include <math.h>
  4 
  5 using namespace cv;
  6 using namespace std;
  7 
  8 Mat src, gray_src, dst;
  9 int threshold_value = 100;
 10 int max_level = 255;
 11 
 12 const char* output_win = "Contours Result";
 13 const char* roi_win = "Final Result";
 14 
 15 void FindROI(int, void*);
 16 void Check_Skew(int, void*);
 17 
 18 int main(int argc, char** argv) {
 19     src = imread("timg.jpg");
 20     if (src.empty()) {
 21         printf("could not load image...
");
 22         return -1;
 23     }
 24     namedWindow("input image", CV_WINDOW_AUTOSIZE);
 25     imshow("input image", src);
 26     namedWindow(output_win, CV_WINDOW_AUTOSIZE);
 27     Check_Skew(0, 0);
 28     // namedWindow(roi_win, CV_WINDOW_AUTOSIZE);
 29     //createTrackbar("Threshold:", output_win, &threshold_value, max_level, FindROI);
 30     // FindROI(0, 0);
 31 
 32     waitKey(0);
 33     return 0;
 34 }
 35 
 36 //将原图放正，如需切边还需执行另一个函数一次（因为不能对斜着的图直接切边）
 37 void Check_Skew(int, void*) {
 38     Mat canny_output;
 39     cvtColor(src, gray_src, COLOR_BGR2GRAY);
 40     Canny(gray_src, canny_output, threshold_value, threshold_value * 2, 3, false);
 41 
 42     vector<vector<Point>> contours;
 43     vector<Vec4i> hireachy;
 44     findContours(canny_output, contours, hireachy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));
 45     Mat drawImg = Mat::zeros(src.size(), CV_8UC3);
 46     float maxw = 0;
 47     float maxh = 0;
 48     double degree = 0;
 49 
 50     //获取最大旋转矩形的尺寸
 51     for (size_t t = 0; t < contours.size(); t++) {
 52         RotatedRect minRect = minAreaRect(contours[t]);
 53         degree = abs(minRect.angle);
 54         if (degree > 0) {//判断是否有旋转
 55             maxw = max(maxw, minRect.size.width);
 56             maxh = max(maxh, minRect.size.height);
 57         }
 58     }
 59     RNG rng(12345);
 60 
 61     //根据最大旋转矩形的尺寸，判断并画出来轮廓同时得到旋转角度
 62     for (size_t t = 0; t < contours.size(); t++) {
 63         RotatedRect minRect = minAreaRect(contours[t]);
 64         if (maxw == minRect.size.width && maxh == minRect.size.height) {//判断是否是最大边界
 65             degree = minRect.angle+90;//判断得是0点到height边的角度，逆时针为负，即使正放也有-90°所以要+90
 66             Point2f pts[4];
 67             minRect.points(pts);
 68             Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
 69             for (int i = 0; i < 4; i++) {
 70                 line(drawImg, pts[i], pts[(i + 1) % 4], color, 2, 8, 0);
 71             }
 72         }
 73     }
 74     printf("max contours width : %f
", maxw);
 75     printf("max contours height : %f
", maxh);
 76     printf("max contours angle : %f
", degree);
 77     imshow(output_win, drawImg);
 78 
 79     //旋转成正的
 80     Point2f center(src.cols / 2, src.rows / 2);//旋转中心
 81     Mat rotm = getRotationMatrix2D(center, degree, 1.0);//函数调用形式：
 82                                                         //Mat getRotationMatrix2D(Point2f center,表示旋转的中心点
 83                                                                                 //double angle, 表示旋转的角度
 84                                                                                 //double scale)        图像缩放因子                                        
 85     Mat dst;
 86     warpAffine(src, dst, rotm, src.size(), INTER_LINEAR, 0, Scalar(255, 255, 255));//仿射变换
 87     imshow("Correct Image", dst);
 88 }
 89 
 90 //无旋转的处理函数，对已经放正的函数切边
 91 void FindROI(int, void*) {
 92 
 93     //提取边缘
 94     cvtColor(src, gray_src, COLOR_BGR2GRAY);
 95     Mat canny_output;
 96     Canny(gray_src, canny_output, threshold_value, threshold_value * 2, 3, false);
 97 
 98     //绘制轮廓
 99     vector<vector<Point>> contours;
100     vector<Vec4i> hireachy;
101     findContours(canny_output, contours, hireachy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));
102 
103     //画出最大轮廓的最小外接矩形
104     int minw = src.cols*0.75;
105     int minh = src.rows*0.75;
106     RNG rng(12345);
107     Mat drawImage = Mat::zeros(src.size(), CV_8UC3);
108     Rect bbox;
109     for (size_t t = 0; t < contours.size(); t++) {
110         RotatedRect minRect = minAreaRect(contours[t]);//获取轮廓t的最小外接矩形，RotatedRect旋转矩形，可以设置矩形中心，矩形长宽，旋转角度
111         float degree = abs(minRect.angle);//获取旋转角度
112         if (minRect.size.width > minw && minRect.size.height > minh && minRect.size.width < (src.cols - 5)) {//轮廓筛选，选出最大的外接矩形
113             printf("current angle : %f
", degree);
114             Point2f pts[4];
115             minRect.points(pts);//将最大的外接矩形的四个点赋给pts
116             bbox = minRect.boundingRect();//外接正矩形边界
117             Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
118             for (int i = 0; i < 4; i++) {
119                 line(drawImage, pts[i], pts[(i + 1) % 4], color, 2, 8, 0);
120             }
121         }
122     }
123     imshow(output_win, drawImage);
124 
125     //用找到的最小外接矩形截取图像
126     if (bbox.width > 0 && bbox.height > 0) {
127         Mat roiImg = src(bbox);//用括号内的范围截取ROI区域
128         imshow(roi_win, roiImg);
129     }
130     return;
131 }