cvtColor(crop, crop, CV_RGB2GRAY);
adaptiveThreshold(crop, crop, 255, CV_ADAPTIVE_THRESH_MEAN_C,CV_THRESH_BINARY, 31, 15);
    Mat dst1, cdst1;
Canny(crop, dst1, 50, 200, 3);
cvtColor(dst1, cdst1, CV_GRAY2BGR);

vector<Vec2f> lines;
// detect lines
HoughLines(dst1, lines, 1, CV_PI/180, 200, 0, 0 );
//HoughLinesP(dst1, lines, 1, CV_PI/180, 150, 0, 0);

// draw lines
for( size_t i = 0; i < lines.size(); i++ )
{
    float rho = lines[i][0], theta = lines[i][1];
    //if( theta>CV_PI/180*170 || theta<CV_PI/180*10){
        Point pt1, pt2;
        double a = cos(theta), b = sin(theta);
        double x0 = a*rho, y0 = b*rho;
        pt1.x = cvRound(x0 + 1000*(-b));
        pt1.y = cvRound(y0 + 1000*(a));
        pt2.x = cvRound(x0 - 1000*(-b));
        pt2.y = cvRound(y0 - 1000*(a));
        line( cdst1, pt1, pt2, Scalar(0,0,255), 3, CV_AA);
    //}
}
namedWindow("detected lines",WINDOW_NORMAL);
imshow("detected lines", cdst1);