I use color Webcamera and I want to know one pixel's color I'm looking for an opencv function that define one pixel's color. for example:
int RED, GREEN, BLUE;
x=1;
y=1;
RED=RedColorFunction(x,y);
GREEN=GreenColorFunction(x,y);
BLUE=BlueColorFunction(x,y);
so I get the first pixel's color. Do you know similar fuction?
oh, please don't use the old api(IplImages, cvfunctions) but instead the new one (cv::Mat, cv::functions)
using namespace cv;
using namespace std;
int main()
{
int x=1, y=1; // pixel location
Mat frame;
namedWindow("cam");
VideoCapture cap(0);
while( cap.isOpened() )
{
cap >> frame;
if ( frame.empty() )
break;
Vec3b pixel = frame.at<Vec3b>( y, x ); // row,col index (NOT x,y)
int b = pixel[0];
int g = pixel[1];
int r = pixel[2];
cout << "r:" << r << " g:" << g << " b:" << b << endl;
imshow("cam",frame);
if ( waitKey(30) == 27) break;
}
return 0;
}
if you got a cv::Mat from your camera, get the pixel:
Vec3b pixel = frame.at<Vec3b>( y, x );
then you can access the colours, note that it's bgr-order here:
int b = pixel[0];
int g = pixel[1];
int r = pixel[2];
so I have this code:
using namespace std;
int b,g,r;
int main() { CvCapture* capture = cvCaptureFromCAM(0);
if ( !capture ) {
fprintf( stderr, "ERROR: capture is NULL \n" );
getchar();
return -1;
} cvNamedWindow( "mywindow", CV_WINDOW_AUTOSIZE );
while ( 1 ) {
IplImage* frame = cvQueryFrame( capture );
cout << b <<" " ;
cout << g <<" " ;
cout << r << endl;
cvShowImage( "mywindow", frame );
if ( (cvWaitKey(10) & 255) == 27 ) break;
}
cvReleaseCapture( &capture );
cvDestroyWindow( "mywindow" );
return 0; }
How can I do this? ( Sorry, I'm very beginner but I must to do it. and thanks for your help.) :)
Asked: 2013-03-10 06:36:46 -0600
Seen: 2,877 times
Last updated: Mar 10 '13