C++:openCV error -

hi trying rgb pixel in image using c++ opencv 2.4.5

but error when compile .

it loads image exception arise when trying rgb pixel

can 1 me please ?

the following code loads image , find rgb pixel @ index 25,4
code :

 #include <opencv2/core/core.hpp>     #include <opencv2/highgui/highgui.hpp>     #include <opencv2/imgproc/imgproc.hpp>     #include <opencv/cv.h>     #include <opencv/highgui.h>     #include <iostream>     using namespace std;     using namespace cv;     int main()     {         int x;         mat input = imread("c:/red.jpg");         if (input.empty())             {                 std::cout << "!!! failed imread(): image not found" << std::endl;                 cin>>x;                 return 0;                 // don't let execution continue, else imshow() crash.             }         imshow("input", input);          vec3f pixel = input.at<vec3f>(25, 40);          if( !pixel[0])          {              std::cout << "!!! failed pixel(): image not found" << std::endl;                 cin>>x;                 return 0;          }             int b = pixel[0];             int g = pixel[1];             int r = pixel[2];         cout<<b;         cout <<" ";         cout<<r;         cout <<" ";         cout <<g;         cin>>b;          /*             // detect squares after filtering...         */         return 0;     } 

you image of type cv_8uc3, means value of pixel stored 3-channel 8-bit uchar. in

vec3f pixel = input.at<vec3f>(25, 40); 

you trying access pixel values floats, since in opencv vec3f defined typedef vec<float, 3> vec3f;. causes program crush. instead should be:

vec3b pixel = input.at<vec3b>(25, 40); 

in opencv vec3b defined typedef vec<uchar, 3> vec3b;, want.

here's documentation cv:: vec data type.

edit can output pixel data with

cout << pixel << endl; 

or this:

printf("[%u, %u, %u]", pixel[0], pixel[1], pixel[2]); 

or this:

int b = static_cast<int>(pixel[0]); int g = static_cast<int>(pixel[1]); int r = static_cast<int>(pixel[2]); cout<< "[" << b <<", " << g << ", " << r << "]" << endl;