Is there a function similar MATLAB's 'impixelinfo()' available in OpenCV? - c++

Question

I'm searching for a function in OpenCV that is similar to impixelinfo() in MATLAB.
impixelinfo() shows you
the location of the pixel (x, y) and
the pixel intensity of your cursor hovering in the image,
like:
impixelinfo() in matlab shows you this
Is there any implementation of this in OpenCV already? Does anyone have a personal version of it created?

Answer 1

You can do something like this:
#include <opencv2/opencv.hpp>
#include <iostream>
using namespace std;
using namespace cv;
Mat img;
void
CallBackFunc(int event,int x,int y,int flags,void* userdata)
{
if(event==EVENT_MOUSEMOVE){
cout << "Pixel (" << x << ", " << y << "): " << img.at<Vec3b>(y,x) << endl;
}
}
int main()
{
// Read image from file
img=imread("demo.jpg");
// Check it loaded
if(img.empty())
{
cout << "Error loading the image" << endl;
exit(1);
}
//Create a window
namedWindow("ImageDisplay",1);
// Register a mouse callback
setMouseCallback("ImageDisplay",CallBackFunc,nullptr);
// Main loop
while(true){
imshow("ImageDisplay",img);
waitKey(50);
}
}
As a result of the helpful comments, I (hopefully) improved the code and now handle grayscale images, and have also set the RGB ordering more akin to how non-OpenCV aficionados might expect it - i.e. RGB rather than BGR. The updated function is below:
void
CallBackFunc(int event,int x,int y,int flags,void* userdata)
{
if(event==EVENT_MOUSEMOVE){
// Test if greyscale or color
if(img.channels()==1){
cout << "Grey Pixel (" << x << ", " << y << "): " << (int)img.at<uchar>(y,x) << endl;
} else {
cout << "RGB Pixel (" << x << ", " << y << "): " << (int)img.at<Vec3b>(y,x)[2] << "/" << (int)img.at<Vec3b>(y,x)[1] << "/" << (int)img.at<Vec3b>(y,x)[0] << endl;
}
}
}