matlab下 hsi转rgb代码

hsi应该是不能在电脑上显示的，要转化为rgb图像。表述或许不准确，体会一下吧。

imshow（）函数默认接收的是rgb图像，按RGB对应矩阵中的值显示。或者显示灰度图imshow(I(:,:,1));

在hsi输入下，hsi矩阵的值会被当成rgb的值来输出。具体结果见附图。

function rgb = hsi2rgb( hsi )
%rgb = hsi2rgb( hsi ) 将hsi图像转化为rgb
%hsi(:,:,1)色调，范围0-1 double 以下同
%hsi(:,:,2)饱和度 
%hsi(:,:,3)亮度
%


hsi = im2double(hsi);
H = hsi(:,:,1)*2*pi;
S = hsi(:,:,2);
I = hsi(:,:,3);

%执行转化
R = zeros(size(hsi,1),size(hsi,2));
G = zeros(size(hsi,1),size(hsi,2));
B = zeros(size(hsi,1),size(hsi,2));

%RG扇形 0 <= H < 2*pi/3
idx = find( (0 <= H) & (H<2*pi/3) );
B(idx) = I(idx) .* (1 - S(idx));
R(idx) = I(idx) .* (1 + S(idx) .* cos(H(idx)) ./ cos(pi/3 - H(idx)) );
G(idx) = 3*I(idx) - (R(idx) + B(idx));

%BG扇形 2*pi/3 <= H < 4*pi/3
idx = find( (2*pi/3 <= H ) & ( H < 4*pi/3) );
R(idx) = I(idx) .* (1 - S(idx));
G(idx) = I(idx) .* (1 + S(idx) .* cos(H(idx) - 2*pi/3) ./ cos(pi - H(idx)) );
B(idx) = 3*I(idx) - (R(idx) + G(idx));

%BR扇形 (4*pi/3) <= H <= (2*pi)
idx = find( (4*pi/3 <= H ) & (H <= 2*pi) );
G(idx) = I(idx) .* (1 - S(idx));
B(idx) = I(idx) .* (1 + S(idx) .* cos(H(idx) - 4*pi/3) ./ cos(5*pi/3 - H(idx)) );
R(idx) = 3*I(idx) - (G(idx) + B(idx));

%合成
rgb = cat(3,R,G,B);
rgb = max(min(rgb,1),0);


end

执行测试代码，rgb2hsi见另一篇文

I = input('input the picture path:\n');
figure(1);
imshow(I),title('原图RGB');
I1 = rgb2hsi(I);
figure(2);
imshow(I1),title('hsi');
figure(3);
imshow(hsi2rgb(I1)),title('rgb');

结果图片：