如何获得图像中像素的颜色（灰色）？

Question

I am using this code to print the intensity of OpenCV Mat pixels. However, I am getting character printed on the console instead of values between 0 and 250:

image1 = imread(nameJpg, 0);
image2 = imread(lastJpg, 0);
for (int j = 0; j < image1.rows-10; j += 1){
    for (int i = 0; i < image1.cols-10; i += 1) {
        std::cout << "" << image1.at<uchar>(i, j) << "    " <<i mage1.at<uchar>(i, j)<<"\n";
    }
}

How can I solve this problem?

Answer 1

You want to cast it to int, such as:

(int)image.at<uchar>(i, j)

You can test this by referring to the ASCII table .

Edit

The source of the bug you're mentioning is from how you access the pixel. i should be for the rows, and j for the columns.

for (int i = 0; i < src.rows; i++) {
    for (int j = 0; j < src.cols; j++)
        cout << (int)src.at<uchar>(i, j) << " ";
    cout << endl;
}

Answer 2

In gray image, the pixel intensity is between 0 and 255 not 250.

If you mean that you want to get the value of a certain pixel, you may use this:

auto image=cv::imread(path,CV_LOAD_IMAGE_GRAYSCALE);
auto pixel_value=image.at<uchar>(row_idx,col_idx);

After OP's edit:

If you want to get number instead of character while printing, use this instead:

auto pixel_value= static_cast<unsigned int>(image.at<uchar>(row_idx,col_idx));