How to find avergae of thresholded elements only from a matrix?

I am trying to calculate average RGB of images with a uniform background. So I want to remove the background from the calculation. How do I select only elements belows above/below certain value (say <250) and calculate average of those only.

[Jan]

@Tarunkishwor Yumnam: Please do not advertise questions in other threads. Imagine the clutter, if all users do this. Thanks.

[Selva Karna]

Avg=mean2(your image (:));

Answer 1

[KSSV]

Let A be your matrix......say you want values below a threshold val.

idx = A<val ; 
themean = mean(A(idx)) ; 

[Tarunkishwor Yumnam]

Thanks!