opencv crop a portion of image within contour

Question

I've just started learning OpenCv. i wanted to crop a portion of an image which is a text surrounded by the red circle. can you guys help me to find the solution like what are all the methods i should follow to crop it. I've tried few things and got the red circle cropped and stored it in a mat.

while(1)
    {
        capture>>img0;
        imshow("original", img0);
        imwrite("original.jpg", img0);
        cv::inRange(img0,cv::Scalar(0,0,100),cv::Scalar(76,85,255),img1);
        imshow("threshold.jpg", img1);
        imwrite("threshold.jpg", img1);
        // find the contours
        vector< vector<Point> > contours;
        findContours(img1, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_NONE);

        Mat mask = Mat::zeros(img1.rows, img1.cols, CV_8UC1);

        drawContours(mask, contours, -1, Scalar(255), CV_FILLED);

        Mat crop(img0.rows, img0.cols, CV_8UC3);

        crop.setTo(Scalar(255,255,255));

        img0.copyTo(crop, mask);

        normalize(mask.clone(), mask, 0.0, 255.0, CV_MINMAX, CV_8UC3);

        imshow("mask", mask);
        imshow("cropped", crop);

        imwrite("mask.jpg", mask);
        imwrite("cropped.jpg", crop);

        if(waitKey(30)=='27')
        {
            break;
        }
    }
    return 0;`[original image[cropped image][1]`

From this image i wanted to crop a text alone. do help me to find the solution by sharing me the methods or steps to follow.

Thanks in advance

Answer 1

If you wish to extract the text alone, you can try this:-

drawContours(mask, contours, -1, Scalar(255), CV_FILLED);
vector<Rect> boundRect( contours.size() );
for(int i=0;i<contours.size();i++)
    {
        boundRect[i] = boundingRect(contours[i]);//enclose in Rect
        Mat ROI,ROI_txt;
        if(boundRect[i].width>30 && boundRect[i].height>30)//ignore noise rects
        {
            ROI=img0(boundRect[i]);//extract Red circle on ROI
            inRange(ROI,Scalar(0,0,0),cv::Scalar(50,50,50),ROI_txt);
            //black colour threshold to extract black text
        }
    }