In one question in which I wanted to calculate the dark (black) area in a binary image, you guys answered to me:
"If all you need is the area of the dark region then you don't need to find the edge at all. You just need to threshold and sum
binaryImage = grayImage < 128; % or whatever.
darkArea = sum(binaryImage);
darkArea2 = bwarea(binaryImage); % Another way using different algorithm. "
Now a problem comes to me. I wonder:
We want the area of black region not white, so when we use sum (or bwarea), we are actually calculating the white area region. right? because white pixels are 1 and black ones are 0 and by summing we are summing the white ones not black ones.
Thus, the area of black region should be this:
image_size = size(binary_image)
whole_area = image_size(1)*image_size(2)
white_area = sum(sum(binary_image)); % or
% white_area = bwarea(binary_image);
black_area = whole_area - white_area;
Am I right?
Sorry for such a trivial question, but I was really confused!
Thanks so much.