# minimum value per pixel (w.r.t channel) in a 3 channel image

Hi everyone,

Is there any function in openCV which can return the minimum/maximum value of a pixel w.r.t channel in a 3 channel image (e.g. a BGR image) like the following available in MATLAB:

```
temp = min(im, [], 3);
```

I know that you can use nested loops to access each pixel using `Mat::at<type>(i,j)`

operator and then use `min`

function twice to get the minimum value per pixel like this:

```
for (int m = 0; m<src.rows; m++)
{
for (int n = 0; n<src.cols; n++)
{
intensity = src.at<Vec3b>(m, n);
rgbmin.at<uchar>(m, n) = min(min(intensity.val[0], intensity.val[1]), intensity.val[2]);
}
}
```

but this seems slower and I am looking for a more efficient way to do this.

Thanks