【二值化】Otsu算法

Otsu算法对图像进行二值化，核心就是计算背景和前景的最大类间方差，把类间方差最大的像素值作为全局二值化的阈值

二值化实现程序

%matlab程序 G = imread('IMG_0019.JPG'); I = rgb2gray(G); [m,n] = size(I); Hist = zeros(255);%直方图 dHist = zeros(255); variance = zeros(255);%方差 PXD = 0; for i = 1:m for j = 1:n Hist(uint8(I(i,j))) = Hist(uint8(I(i,j))) + 1; end end for i = 1:255 dHist(i) = Hist(i)/(m*n); end for PXD = 1:255 w0 = 0; w1 = 0; g0 = 0; g1 = 0; for i = 1:PXD g0 = g0 + i*dHist(i); w0 = w0 + dHist(i); end for i = PXD+1 : 255 g1 = g1 + i*dHist(i); w1 = w1 + dHist(i); end variance(PXD) = w0*w1*(g0 - g1)*(g0 - g1); end PXD = 1; for i = 1:255 if variance(PXD) < variance(i) PXD = i; end end for i = 1:m for j = 1:n if I(i,j) > PXD I(i,j) = 255; else I(i,j) = 0; end end end imagBW = I;