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I've never studied opencv and I'm trying to learn the basic of opencv and I used similar code to this from one of the tutorial in the net and I want to detect the color of the shape all of my shapes have the same color which is green how can I do this using open cv I use opencv 2.4.9 and xcode

I found this tutorial but it use Python can I still follow http://www.pyimagesearch.com/2014/08/...

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <cmath>
#include <iostream>

/**
 * Helper function to find a cosine of angle between vectors
 * from pt0->pt1 and pt0->pt2
 */
static double angle(cv::Point pt1, cv::Point pt2, cv::Point pt0)
{
    double dx1 = pt1.x - pt0.x;
    double dy1 = pt1.y - pt0.y;
    double dx2 = pt2.x - pt0.x;
    double dy2 = pt2.y - pt0.y;
    return (dx1*dx2 + dy1*dy2)/sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10);
}

/**
 * Helper function to display text in the center of a contour
 */
void setLabel(cv::Mat& im, const std::string label, std::vector<cv::Point>& contour)
{
    int fontface = cv::FONT_HERSHEY_SIMPLEX;
    double scale = 0.4;
    int thickness = 1;
    int baseline = 0;

    cv::Size text = cv::getTextSize(label, fontface, scale, thickness, &baseline);
    cv::Rect r = cv::boundingRect(contour);

    cv::Point pt(r.x + ((r.width - text.width) / 2), r.y + ((r.height + text.height) / 2));
    cv::rectangle(im, pt + cv::Point(0, baseline), pt + cv::Point(text.width, -text.height), CV_RGB(255,255,255), CV_FILLED);
    cv::putText(im, label, pt, fontface, scale, CV_RGB(0,0,0), thickness, 8);
}

int main()
{
    //cv::Mat src = cv::imread("polygon.png");
    cv::Mat src = cv::imread("assets/basic-shapes-2.png");
    if (src.empty())
        return -1;

    // Convert to grayscale
    cv::Mat gray;
    cv::cvtColor(src, gray, CV_BGR2GRAY);

    // Use Canny instead of threshold to catch squares with gradient shading
    cv::Mat bw;
    cv::Canny(gray, bw, 0, 50, 5);

    // Find contours
    std::vector<std::vector<cv::Point> > contours;
    cv::findContours(bw.clone(), contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);

    std::vector<cv::Point> approx;
    cv::Mat dst = src.clone();

    for (int i = 0; i < contours.size(); i++)
    {
        // Approximate contour with accuracy proportional
        // to the contour perimeter
        cv::approxPolyDP(cv::Mat(contours[i]), approx, cv::arcLength(cv::Mat(contours[i]), true)*0.02, true);

        // Skip small or non-convex objects 
        if (std::fabs(cv::contourArea(contours[i])) < 100 || !cv::isContourConvex(approx))
            continue;

        if (approx.size() == 3)
        {
            setLabel(dst, "TRI", contours[i]);    // Triangles
        }
        else if (approx.size() >= 4 && approx.size() <= 6)
        {
            // Number of vertices of polygonal curve
            int vtc = approx.size();

            // Get the cosines of all corners
            std::vector<double> cos;
            for (int j = 2; j < vtc+1; j++)
                cos.push_back(angle(approx[j%vtc], approx[j-2], approx[j-1]));

            // Sort ascending the cosine values
            std::sort(cos.begin(), cos.end());

            // Get the lowest and the highest cosine
            double mincos = cos.front();
            double maxcos = cos.back();

            // Use the degrees obtained above and the number of vertices
            // to determine the shape of the ...