Try the following:
Variables 'dark_number' and 'dark_percent' reports the number and percentage of black pixels in each ROI respectively.
Each row refers to each binary image and each column refers to each ROI. So the number of columns are always 4 while row number varies
clear; clc;
[filename_roi,pathname_roi] = uigetfile('*.png','Select ROI png Files','MultiSelect', 'on');
if ~iscell(filename_roi)
filename_roi = {filename_roi};
end
Nroi = length(filename_roi);
ROI = cell(1,Nroi);
for r = 1:Nroi
ROI{1,r} = imread(fullfile(pathname_roi,filename_roi{r}));
end
%
[filename,pathname] = uigetfile('*.png','Select One or More png Files','MultiSelect', 'on');
if ~iscell(filename)
filename = {filename};
end
Nz = length(filename);
white_mask = cellfun(@nnz,ROI);
dark_number = zeros(Nz,Nroi);
for k = 1:Nz
I = imread(fullfile(pathname,filename{k}));
white_number = cellfun(@(x) sum((I & x),'all'),ROI);
dark_number(k,:) = white_mask - white_number;
end
dark_percent = 100*dark_number./white_mask
