RGB 图像转HSI图像

function hsi=rgb2hsi(image)
% image=imread('SKY.bmp');
rgb_r=image(:,:,1);
rgb_g=image(:,:,2);
rgb_b=image(:,:,3);
[width,height]=size(rgb_r);
hsi=zeros(width,height,3);
hsi_h=hsi(:,:,1);
hsi_s=hsi(:,:,2);
hsi_i=hsi(:,:,3);
PI=3.1415956;
for i=1:width
     for j=1:height
         R=double(rgb_r(i,j));G=double(rgb_g(i,j));B=double(rgb_b(i,j));
        min = R;
if (G < min)
   min = G;
     end
if (B < min)
   min = B;
     end
I =(R+G+B)/3;
S = 1 - min/I;
if (S == 0.0)
   H = 0;
     else
   H = ((R-G)+(R-B))/2.0;
   H = H/sqrt((R-G)*(R-G) + (R-B)*(G-B));
   H = acos(H);
   if (B > G)