There is an advantage in MATLAB that when a function is created, it can be used as a command in another file. say for example,
%Type this in one file
A=imread('input.jpg'); % Reads input Image
B = imagedisplay(A); % Call the function image display
% Here A, input argument, B output argument
figure, imshow(B);
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%Type this in other file
function [output_img] = imagedisplay(input_img)
output_img = rgb2gray(input_img);
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This function returns an image called ' output_img' and that is displayed in the main program.
