The first moment is defined average intensity of each color component
Second moment, color variance test reflection region, i.e. inhomogeneity
Third moment defined skewness color components, i.e., the color asymmetry
close all;clear all;clc;
J = imread('lena.jpg');
K = imadjust(J,[70/255 160/255],[]);
figure;
subplot(121),imshow(J);
subplot(122),imshow(K);
[m,n] = size(J);
mm = round(m/2);
mn = round(n/2);
[p,q] = size(K);
pp = round(p/2);
qq = round(q/2);
J = double(J);
K = double(K);
colorsum = 0.0;
Javg = mean2(J) %求原图像一阶矩
Kavg = mean2(K) %求增强对比度后的图像一阶矩
Jstd = std(std(J)) %求原图像的二阶矩，因为一次std函数表示按列求标准差，两次std表示求整个矩阵的标准差
Kstd = std(std(K)) %求增强对比度后的图像二阶矩
for i=1:mm
for j=1:mn
colorsum = colorsum+(J(i,j)-Javg)^3;
end
end
Jske = (colorsum/(mm*mn))^(1/3) %求原图像的三阶矩
colorsum = 0.0;
for i=1:pp
for j=1:qq
colorsum = colorsum + (J(i,j)-Kavg)^3;
end
end
Kske = (colorsum/(pp*qq))^(1/3) %求增强对比度后的图像三阶矩
Section Function Description:
mean2 (A): averaging matrix A
std (x, flag, dim): find the standard deviation of x
std (x, 0,1): 0 In addition to n-1,1 by column represents time division request indicates standard deviation
std (x, 1,2): 1 indicates inter n, 2 denotes dividing line when evaluated by standard deviation