OpenCV Display Pixels Value

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I have below code. When I run the program, unknown characters instead of pixel values comes to the screen. I want to display pixel values. How do I do this? Thank you.

#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main()
{
    Mat image = imread("/home/fd/baby.jpg");
    for( int i = 0 ; i < image.rows ; i++)
    {
        for( int j = 0 ; j < image.cols ; j++ )
        {
            if(image.type() == CV_8UC1)
            {
                image.at<uchar>(i,j) = 255;
            }
            else if(image.type() == CV_8UC3)
            {
                cout << image.at<Vec3b>(i,j)[0] << " " << image.at<Vec3b>(i,j)[1] << " " << image.at<Vec3b>(i,j)[2] << endl;

                image.at<Vec3b>(i,j)[0] = 255;
                image.at<Vec3b>(i,j)[1] = 255;
                image.at<Vec3b>(i,j)[2] = 255;

                cout << image.at<Vec3b>(i,j)[0] << " " << image.at<Vec3b>(i,j)[1] << " " << image.at<Vec3b>(i,j)[2] << endl;
            }
            else
            {
                cout << "Anknown image format" << endl;
                return 0;
            }
        }
    }
    imshow("Result İmage", image);
    waitKey(0);
}

This is the result screen:

Cast each of the outputs to an integer

<< image.at<Vec3b>(i,j)[0] ...

change to

<< (int)image.at<Vec3b>(i,j)[0] ...

You are printing a char (or probably unsigned char) which is printed through the stream as a single character (which at 255 looks like what you see). Cast to int forces it to display the numerical representation of the value.

The other answers changing the image.at<type> changes how the raw data is interpreted; don't do that. They must be interpreted properly.

Operations with images — OpenCV 2.4.13.7 documentation, In order to get pixel intensity value, you have to know the type of an for a single channel grey scale image (type 8UC1) and pixel coordinates x and y: namedWindow("image", CV_WINDOW_AUTOSIZE); imshow("image",� OpenCV Display Pixels Value. Ask Question Asked 4 years, 10 months ago. Active 3 months ago. Viewed 7k times 2. I have below code. When I run the program, unknown

Change the

image.at<Vec3b>(i, j)

to

image.at<int>(i, j)

or

image.at<double>(i, j)

or

image.at<float>(i, j)

to print the values instead of characters

How to get pixel's value from a picture?, The C++ interface has a very handy function: at(), which allows for random access of pixel values in a Mat object, the OpenCV image storage� C++ version only: intensity.val[0] contains a value from 0 to 255. Note the ordering of x and y. Since in OpenCV images are represented by the same structure as matrices, we use the same convention for both cases - the 0-based row index (or y-coordinate) goes first and the 0-based column index (or x-coordinate) follows it.

Vec3b px= image.at(x,y);

cout << "value: ("<<(int)px.val[0]<<", "<<(int)px.val[1]<<", "<<(int)px.val[2]<<")" << endl;

This works form me.

#000 How to access and edit pixel values in OpenCV with Python?, OpenCV. Also, learn how to convert RGB and BGR using OpenCV with Python. We call these values pixels and they collectively represent an image. Basically To display an image, we will use the cv2.imshow() function. If we are dealing with a grayscale image, we are using numeric values from 0 (black pixels) up to 255 (white pixels). Any number in between these two is a shade of gray. On the other hand, color images are represented with three matrices. Each of those matrices represent one primary color which is also called a channel.

You are displaying characters try converting using function image.at<int>(j,i);

reunanen/opencv-show-pixel-value: Display images using , Display images using OpenCV so that pixel values are displayed on mouse hover. - reunanen/opencv-show-pixel-value. So what you do is simply split the whole histogram to 16 sub-parts and value of each sub-part is the sum of all pixel count in it. This each sub-part is called "BIN". In first case, number of bins were 256 (one for each pixel) while in second case, it is only 16. BINS is represented by the term histSize in OpenCV docs.

opencv, opencv documentation: Setting and getting pixel values of a Gray image in C++. file\n\n"; // show error message on command line return(0); // and exit program � low_pixel = pic < 20 # to ensure of it let's check if all values in low_pixel are True or not if low_pixel.any() == True: print(low_pixel.shape) (1079, 1293, 3) Now as we said, a host variable , well this name is not traditionally used but i refer it because it behaves.

Assessing the pixel values of an image, OpenCV examples for Assessing the pixel values of an image. CV_BGR2GRAY); namedWindow( "Gray image", CV_WINDOW_AUTOSIZE ); imshow( "Gray� We can access a pixel value by its row and column coordinates. For BGR image, it returns an array of Blue, Green, Red values. For grayscale image, corresponding intensity is returned. We get BGR value from the color image:

Tutorial 6, Today I'm going to show you how to assessing the pixel values of an image using OpenCv. Digital color images are made out of pixels. First we� Size( w, h ): Defines the size of the kernel to be used ( of width w pixels and height h pixels) Point(-1, -1): Indicates where the anchor point (the pixel evaluated) is located with respect to the neighborhood. If there is a negative value, then the center of the kernel is considered the anchor point.

Comments
  • possible duplicate of Why is std::cout not printing the correct value for my int8_t number?
  • But you know picture of pixels have values between 0 and 255. So I think my problem is not signed or unsigned pixel value.
  • cout << int(uchar_value); but better even, just print the whole Mat: cout << img << endl;
  • It's not about signed or unsigned. Any flavour of char is printed as a single character not a number by default. Promoting to a bigger type prevents this. (If cout << 'A' printed 65 it would cause confusion. Blame backward compatibility.)
  • Thank you @berak, I solved my problem wity your answer. Thank you. cout << int(image.at<Vec3b>(i,j)[0])