MATLAB: How can i plot a histogram of pixel values

Question

i'm working on a simulation and it contains a histogram of pixel differences for original image and marked one. but i do not understand this plot (that comes in attachment). can anybody please review it and guide me on that?

Answer 1

Your plot shows that there is a pixel-to-pixel difference (same location) of anywhere from -4 to +0.5 gray levels.

diffImage = double(image1) - double(image2);
minValue = min(diffImage(:));
maxValue = max(diffImage(:));
edges = linspace(minValue, maxValue, 500); % 500 bins
counts = histc(diffImage(:));
plot(edges, counts, 'b-');
grid on;