opencv实现图像倾斜校正

#include <iostream>
#include"opencv2/opencv.hpp"
using namespace std;
using namespace cv;


bool cmp_x(cv::Point pt1, cv::Point pt2)
{
    return (pt1.x < pt2.x);
}

cv::Point2f get_mid_pt(cv::Point2f pt1, cv::Point2f pt2)
{
    return cv::Point2f((pt1.x + pt2.x)/2.0,(pt1.y + pt2.y) / 2.0);
}

double get_point_angle(cv::Point2f pointO,cv::Point2f pointA)
{
    double angle = 0;
    cv::Point2f point;
    double temp;
    point = cv::Point2f((pointA.x - pointO.x), (pointA.y - pointO.y));

    if ((0==point.x) && (0==point.y))
    {
        return 0;
    }

    if (0==point.x)
    {
        angle = 90;
        return angle;
    }

    if (0==point.y)
    {
        angle = 0;
        return angle;
    }

    temp = fabsf(float(point.y)/float(point.x));
    temp = atan(temp);
    temp = temp*180/CV_PI ;

    if ((0<point.x)&&(0<point.y))
    {
        angle = 360 - temp;
        return angle;
    }

    if ((0>point.x)&&(0<point.y))
    {
        angle = 360 - (180 - temp);
        return angle;
    }

    if ((0<point.x)&&(0>point.y))
    {
        angle = temp;
        return angle;
    }

    if ((0>point.x)&&(0>point.y))
    {
        angle = 180 - temp;
        return angle;
    }

    printf("sceneDrawing :: getAngle error!");
    return -1;
}

int RotateImage(const cv::Mat &src, double angle, cv::Mat &dst, cv::Mat &rot_matrix, bool crop = true, int flags = cv::INTER_NEAREST,
                int borderMode = cv::BORDER_CONSTANT, const cv::Scalar &borderValue = cv::Scalar())
{
    if(0 == src.cols * src.rows) { return 0;}
    cv::Point2f center(src.cols / 2.0f, src.rows / 2.0f);
    rot_matrix = cv::getRotationMatrix2D(center, angle, 1.0);
    if (crop) {
        if (dst.data == NULL) {
            dst = cv::Mat(src.rows, src.cols, src.type());
        }
    } else {
        cv::Rect bbox = cv::RotatedRect(center, cv::Size2f(src.cols, src.rows), angle).boundingRect();
        double *p = (double *) rot_matrix.data;
        p[2] += bbox.width / 2.0 - center.x;
        p[5] += bbox.height / 2.0 - center.y;
        if (dst.rows != bbox.height || dst.cols != bbox.width) {
            dst = cv::Mat(bbox.height, bbox.width, src.type());
        }
    }
    cv::warpAffine(src, dst, rot_matrix, dst.size(), flags, borderMode, borderValue);
    return 0;
}


int main(int argc, char *argv[])
{
    cv::Mat img = cv::imread("/data_1/everyday/0325/13.jpeg");

    cv::Mat m_gray,m_bi;
    cv::cvtColor(img,m_gray,CV_BGR2GRAY);
    cv::threshold(m_gray,m_bi,100,255,THRESH_BINARY_INV);

    vector<vector<Point>> contours;
    vector<Vec4i> hierarchy;
    findContours(m_bi,contours,hierarchy,RETR_TREE,CHAIN_APPROX_SIMPLE,Point());

    RotatedRect rt_rot_max,rt_tmp;
    int max_szie = -1;
    for(int i=0;i<contours.size();i++)
    {
        rt_tmp = minAreaRect(Mat(contours[i]));
        if(rt_tmp.size.area() > max_szie)
        {
            max_szie = rt_tmp.size.area();
            rt_rot_max = rt_tmp;
        }
    }
    std::vector<cv::Point2f> v_pt(4);
    rt_rot_max.points(v_pt.data());

    std::sort(v_pt.begin(),v_pt.end(),cmp_x);

    cv::Point2f pt_left = get_mid_pt(v_pt[0], v_pt[1]);
    cv::Point2f pt_right = get_mid_pt(v_pt[2], v_pt[3]);

    double ang = get_point_angle(pt_left,pt_right);
    std::cout<<"ang="<<ang<<std::endl;

    cv::circle(img,v_pt[0],6,Scalar(50,12,189),3);
    cv::circle(img,v_pt[1],6,Scalar(10,255,255),3);
    cv::circle(img,v_pt[2],6,Scalar(150,120,19),3);
    cv::circle(img,v_pt[3],6,Scalar(0,0,0),3);

    cv::Mat m_rot,rot_matrix;
    RotateImage(img, -ang, m_rot, rot_matrix, false);

    cv::imshow("m_rot",m_rot);
    cv::imshow("m_bi",m_bi);
    cv::imshow("m_gray",m_gray);
    cv::imshow("img",img);
    cv::waitKey(0);

    return 0;
}