Getting pixel value in OpenCV

Question

I'm new to OpenCV and I'm trying to get the pixel value from a grayscale image.

#include<opencv2\opencv.hpp> #include<opencv2\highgui\highgui.hpp> #include<opencv2\core\core.hpp> #include<iostream> using namespace cv; int main() { VideoCapture cap(1); Mat image,gray_image; cap>>image; cvtColor(image,gray_image,CV_BGR2GRAY); std::cout<<"Value: "<<gray_image.at<uchar>(0,0); imshow("Window",gray_image); waitKey(0); return 0; }

The pixel value is displayed as * or ~ etc. I think it is getting converted to ASCII value. How do I fix that?

Thank you.

possible duplicate of Visualization pixel with Opencv Mat at — Bull
– Bull, Commented Nov 21, 2013 at 10:05

AlexBG · Accepted Answer · 2013-11-21 07:59:54Z

4

Try to output as integer

std::cout<<"Value: "<<static_cast<int>(gray_image.at<uchar>(0,0));

answered Nov 21, 2013 at 7:59

AlexBG

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Comments

Haris · Accepted Answer · 2013-11-21 07:58:36Z

You need to typecast your uchar variable to int before printing

like,

std::cout<<"Value: "<<(int)src.at<uchar>(0,0);

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