row = 256;
col = 256;
mask = zeros(row, col);
% 32 vertical lines in the middle (or one vertical line 32 columns wide)
mask(:, 113:144) = 1;
% create 30 other vertical lines at random:
idx_avail = 1:col; % column indexes available for the new random lines
idx_avail(113:144) = []; % don't allow random lines in the middle
% 30 random numbers chosen from idx_avail without repeats:
% randperm(N_avail,30) returns 30 unique integers between 1 and N_avail, inclusive
% then idx_avail(randperm(__)) converts those to indexes of columns of mask
N_avail = numel(idx_avail);
random_idx = idx_avail(randperm(N_avail,30));
% put the lines in place:
mask(:,random_idx) = 1;
figure, imshow(mask);
save("new-created-mask.mat", "mask");
