Hi Sarah,
In the code you mentioned, I have assumed that in your second line of code, you are binarizing I and not IBW and your code is
IBW = 0.01*imbinarize(I);
From my understanding of the problem, you are binarizing a greyscale image, scaling it down by a factor of 100, summing it up with a rotated version of the image and then trying to find the white percentage. While using the equation:
PercentWhite = (1-nnz(stack)/numel(stack))*100;
since all the pixel values of the image matrix stack are non-zero, the function 'nnz' returns the total number of elements. Hence, the equation becomes (1-1)*100. To resolve the issue, you can follow one out of the following two steps:-
1. If you just want to count the number of pixels which are fully white i.e. value 1, you can use the 'floor' function to make all the values between zero and one 0.
stack = imcomplement(IBW + Irot);
stack_floor=floor(stack);
PercentWhite = (1-nnz(stack_floor)/numel(stack_floor))*100;
2. If you want a range of values of pixels to be counted as whites(e.g. if pixel value is >0.7), then, you can use a code like this:-
th=0.7;
th_comp=1-th; %complemented threshold
I = imcomplement(imread(figname));
IBW = 0.01*imbinarize(I);
Irot = imrotate(IBW, 90);
stack = imcomplement(IBW + Irot);
PercentWhite = (1-nnz(stack<th_comp)/numel(stack))*100
Hope this helps!
