RGB 颜色空间转 HSI 颜色空间的matlab程序实现

RGB 颜色空间转 HSI 颜色空间的matlab程序实现

2014.10.20之前的内容有误，这里根据wikipedia更新了算法内容. 算法以wiki为准

https://en.wikipedia.org/wiki/HSL_and_HSV

这里demo出 HSI中 S 空间的图像和暗通道图的对比.

会发现，确实右边到很暗，这是因为HSV转换的时候对RGB值做了归一化处理，如果打印出归一化处理后的R+G+B值会发现输出图像很亮(白茫茫一片～)



下图是取自图像第321列的数据分布，可以看见图像的灰度分布是很明晰的



下面给出了我写的转换函数，直接调用即可.

%%**************************************************************************
% Function writer : EOF
% code file : RGB2SHI_Color.m
% code date : 2014.10.16
% Translate RGB into HSI-space
%
% Code Description:
%
% If you want to translate a colourful Image which is coded as
% RGB colour space into HSI space, what you need to do is just input your
% colour image.
%
% This function would return HSI as a matrix [H,S,I].
%
%% *************************************************************************
function [H,S,I] = RGB2SHI_Color(Image)

if size(Image,3) ~= 3
fprintf('ERROR Imput-Image must be three channel image\n');
return;
end

Height_Image = size(Image,1);
Width_Image = size(Image,2);
Channel_Image = size(Image,3);

H = zeros(1,Height_Image * Width_Image);
H_temp = zeros(1,Height_Image * Width_Image);
S = zeros(1,Height_Image * Width_Image);
I = zeros(1,Height_Image * Width_Image);
%% Normalization into (0,1)
R_temp = double(Image(:,:,1));
G_temp = double(Image(:,:,2));
B_temp = double(Image(:,:,3));

R = R_temp./(R_temp + G_temp + B_temp);
G = G_temp./(R_temp + G_temp + B_temp);
B = B_temp./(R_temp + G_temp + B_temp);

Max_channel = max(max(R,G),B);
Min_channel = min(min(R,G),B);
Difference = Max_channel - Min_channel;

I = (R + G + B)./3;

for row = 1:Height_Image
for col = 1: Width_Image

% In fact , if Difference(row,col) is zero, the H_temp is
% undefine , it means that H_temp(row,col) close to
% infinite.
if Difference(row,col) == 0
H_temp(row,col) = 0;
end

if Max_channel(row,col) == R(row,col)
H_temp(row,col) = mod((G(row,col) - B(row,col)) ...
./Difference(row,col), 6 );
end

if Max_channel(row,col) == G(row,col)
H_temp(row,col) = (B(row,col) - R(row,col)) ...
./Difference(row,col) + 2;
end

if Max_channel(row,col) == B(row,col)
H_temp(row,col) = (B(row,col) - R(row,col)) ...
./Difference(row,col) + 4;
end

H(row,col) = H_temp(row,col)*60;

if I(row,col) == 0
S(row,col) = 0;
else
S(row,col) = 1 - (Min_channel(row,col)./I(row,col));
end
end
end

end