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Sort bounding boxes in x- Axis of a image in order

asked 2013-09-02 12:25:12 -0500

Vanushka gravatar image

updated 2017-12-27 17:12:03 -0500

In this cord it finds all the contours and extract each contour and save them as .jpg randomly . But is there a method to save the images in order from left to right (e.g. as 1.jpg, 2.jpg, 3.jpg...).

Any suggestions will be greatly appreciated. Thank you.

image description

int main() {

cv::Mat img_ori= cv::imread("NumberPlate.jpg");
if (!img_ori.data)
{
std::cout << "Image file not found\n";
return 1;
}

cv::Mat img_threshold;
// threshold image
cv::cvtColor(img_ori, img_threshold, CV_BGR2GRAY);
//cv::threshold(img_threshold,img_threshold, 150, 255, CV_THRESH_BINARY_INV);
//cv::adaptiveThreshold(img_threshold, img_threshold,255,CV_ADAPTIVE_THRESH_GAUSSIAN_C, CV_THRESH_BINARY,15,-5);
cv::threshold(img_threshold, img_threshold, 128, 255,CV_THRESH_BINARY_INV | CV_THRESH_OTSU);

cv::Mat binary;
cv::erode(img_threshold,binary,cv::Mat(),cv::Point(-1,-1),2);
cv::dilate(img_threshold,binary,cv::Mat(),cv::Point(-1,-1),3);

//Search contours
cv::Mat blur_out(img_threshold);
cv::vector<cv::vector<cv::Point> > contours;
cv::vector<cv::Point> points;
cv::vector<cv::Vec4i> hierarchy;

//cv::Mat canny_output;
//int thresh = 100;

//Canny( img_threshold, canny_output, thresh, thresh*2, 3 );

//findContours(blur_out, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
findContours(img_threshold, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
// Approximate contours to polygons + get bounding rects 
cv::vector<cv::vector<cv::Point> > contours_poly( contours.size() );
cv::vector<cv::Rect> boundRect( contours.size() );
cv::vector<cv::Point2f>center( contours.size() );
cv::vector<float>radius( contours.size() );

for( int i = 0; i < contours.size(); i++ )
{
approxPolyDP( cv::Mat(contours[i]), contours_poly[i], 3, true );
boundRect[i] = cv::boundingRect( cv::Mat(contours_poly[i]) );
}

//Draw bounding rect
int x=1;
cv::Mat drawing(img_ori);
for( int i = 0; i< contours.size(); i++ )
{
    std::stringstream s;
    s << x;
    std::string str1 = s.str();
    cv::Scalar color = cv::Scalar(0,255,0);

    if(boundRect[i].height>50 && boundRect[i].width>25)
    {
    rectangle( drawing, boundRect[i].tl(), boundRect[i].br(), color, 2, 8, 0 );
    cv::Rect region_of_interest = cv::Rect(boundRect[i].x,boundRect[i].y,boundRect[i].width,boundRect[i].height);
    cv:: Mat imageroi=img_ori(region_of_interest);

    //templates.Add(new Comparison<FoundTemplateDesc>((t1, t2) => -t2.sample.contour.SourceBoundingRect.X.CompareTo(t1.sample.contour.SourceBoundingRect.X)));

    std::stringstream ss;
    ss << i;
    std::string str = ss.str();
    const char *cstr = str.c_str();

    cv::imwrite( str1+".jpg", imageroi );

    cvNamedWindow(cstr,CV_WINDOW_AUTOSIZE);
    imshow(str,imageroi);
    x++;
    }
}

imshow("Box",img_ori);

cvWaitKey(0);

return 0;

}

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answered 2013-09-02 13:22:43 -0500

berak gravatar image

if you got a vector<Rect>, you can use std::sort, all you need is a compare function:

bool compare_rect(const Rect & a, const Rect &b) {
    return a.x < b.x;
}

vector<Rect> rects;
sort( rects.begin(), rects.end(), compare_rect );
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Asked: 2013-09-02 12:25:12 -0500

Seen: 4,749 times

Last updated: Sep 02 '13