可视化像素与Opencv Mat在

I don't understand why output is a strange number when I run my code:

我不明白为什么在运行代码时输出是一个奇怪的数字:

int main(int argc, char** argv)
{
    Mat im;
    im = imread("lena.png", CV_LOAD_IMAGE_GRAYSCALE);
    cout << im.at<uchar>(0, 0) << endl;
    waitKey(0);
}

If I visualize image I see the correct image. Where am I wrong?

如果我可视化图像,我会看到正确的图像。我哪里错了?

2 个解决方案

#1

Because it shows the symbol, like cout << char(123) << endl;

因为它显示符号,如cout << char(123)<< endl;

You have to use int cast:

你必须使用int cast:

cout << (int) im.at<uchar>(0, 0) << endl;

#2

As stated in the official documentation you don´t get the actual intensity value directly but a scalar.

正如官方文档中所述,您不能直接获得实际强度值,而是标量。

Try this:

Scalar intensity = im.at<uchar>(0, 0);

cout << intensity.val[0] << endl;

and for images with more than one channel you can use:

对于具有多个频道的图像,您可以使用:

Vec3b intensity = im.at<Vec3b>(0, 0);
cout << intensity.val[0] << intensity.val[1] << intensity.val[2] << endl;

#1