img.at<Vec3b> giving 3 values for grayscale image

C++
1

Hi,
When I’m reading image as COLOR image, I’m getting appropriate intensity (3 values) at each at pixel (y,x).

 Vec3b intensity = img.at<Vec3b>(y, x);
 unsigned int blue = intensity.val[0];
 unsigned int green = intensity.val[1];
 unsigned int red = intensity.val[2];

However, when I’m reading same image as GRAYSCALE, and trying to applying same code as above, I’m still getting 3 intensity values. & all the 3 values are different compared to if I read intensity for single channel using below code:

 uchar intensity = img.at<uchar>(y, x);

Not understanding why I’m getting 3 values for grayscale image and that to something different from actual gray pixel intensities.
Thanks in advance.

2

if it’s grayscale, then accessing with Vec3b is an error

3

indeed, those are the next 2 grayscale pixels.

if you run a debug build, you should get a proper exception

1 Like