Counting Voxels in a Binary Mask

I have a mask, which is binary and 3-D. I want to count the number of white voxels. How can I do it?

Answer 1

[Iain]

if white is true:

 count_of_white_voxels = sum(mask(:)) ;

[Jamuna Jayashri Mahalingam]

I am using masks in NIFTI format. Here is my code:

clc; nii= load_nii('Seg.nii');%% loading NIFTI files view_nii(nii); %Count voxels count_of_white_voxels = sum(mask(:));

I keep getting this error: Undefined function 'sum' for input arguments of type 'struct'

[Jamuna Jayashri Mahalingam]

I think i figured what the error is..

 I used 
 count_of_white_voxels = sum(nii.img(:)) ;

Now there is no error