需求：

     求图像的最大灰度、最小灰度、以及平均灰度。

代码如下：

% BY SCOTT
% Count max gray and min gray

clear all;
clc;
rgb = imread('test.jpg');
gray = rgb2gray(rgb);
[m,n] = size(gray);
max = 0;
min = 255;
sum = 0;
avg = 0;

for i=1:1:m
    for j=1:1:n
        if (gray(i,j) > max)
            max = gray(i,j);
        end
        if (gray(i,j) < min)
            min = gray(i,j);
        end
        sum = sum + double(gray(i, j));
    end
end

avg = sum/(m*n);
imshow(rgb); figure; imshow(gray);

MATLAB图像处理_统计最大/最小/平均灰度