rgb2hsv.m

可用于对信号的频谱进行分析,希望站长能整理好,以便大家互相学习

function [h,s,v] = rgb2hsv(r,g,b)
%RGB2HSV Convert red-green-blue colors to hue-saturation-value.
%   H = RGB2HSV(M) converts an RGB color map to an HSV color map.
%   Each map is a matrix with any number of rows, exactly three columns,
%   and elements in the interval 0 to 1.  The columns of the input matrix,
%   M, represent intensity of red, blue and green, respectively.  The
%   columns of the resulting output matrix, H, represent hue, saturation
%   and color value, respectively.
%
%   HSV = RGB2HSV(RGB) converts the RGB image RGB (3-D array) to the
%   equivalent HSV image HSV (3-D array).
%
%   CLASS SUPPORT
%   -------------
%   If the input is an RGB image, it can be of class uint8, uint16, or 
%   double; the output image is of class double.  If the input is a 
%   colormap, the input and output colormaps are both of class double.
% 
%   See also HSV2RGB, COLORMAP, RGBPLOT. 

%   Undocumented syntaxes:
%   [H,S,V] = RGB2HSV(R,G,B) converts the RGB image R,G,B to the
%   equivalent HSV image H,S,V.
%
%   HSV = RGB2HSV(R,G,B) converts the RGB image R,G,B to the 
%   equivalent HSV image stored in the 3-D array (HSV).
%
%   [H,S,V] = RGB2HSV(RGB) converts the RGB image RGB (3-D array) to
%   the equivalent HSV image H,S,V.

%   See Alvy Ray Smith, Color Gamut Transform Pairs, SIGGRAPH '78.
%   C. B. Moler, 8-17-86, 5-10-91, 2-2-92.
%      revised by C. Griffin for uint8 inputs 7-26-96
%      revised by P. Gravel for faster execution and less memory
%   Copyright 1984-2003 The MathWorks, Inc. 
%   $Revision: 5.15.4.1 $  $Date: 2003/05/01 20:43:53 $


switch nargin
  case 1,
     if isa(r, 'uint8'), 
        r = double(r) / 255; 
     elseif isa(r, 'uint16')
        r = double(r) / 65535;
     end
  case 3,
     if isa(r, 'uint8'), 
        r = double(r) / 255; 
     elseif isa(r, 'uint16')
        r = double(r) / 65535;
     end
     
     if isa(g, 'uint8'), 
        g = double(g) / 255; 
     elseif isa(g, 'uint16')
        g = double(g) / 65535;
     end
     
     if isa(b, 'uint8'), 
        b = double(b) / 255; 
     elseif isa(b, 'uint16')
        b = double(b) / 65535;
     end
     
  otherwise,
      error('MATLAB:rgb2hsv:WrongInputNum', 'Wrong number of input arguments.');
end
  
threeD = (ndims(r)==3); % Determine if input includes a 3-D array

if threeD,
  g = r(:,:,2); b = r(:,:,3); r = r(:,:,1);
  siz = size(r);
  r = r(:); g = g(:); b = b(:);
elseif nargin==1,
  g = r(:,2); b = r(:,3); r = r(:,1);
  siz = size(r);
else
  if ~isequal(size(r),size(g),size(b)), 
    error('MATLAB:rgb2hsv:InputSizeMismatch', 'R,G,B must all be the same size.');
  end
  siz = size(r);
  r = r(:); g = g(:); b = b(:);
end

v = max(max(r,g),b);
s = zeros(size(v));
h = zeros(size(v));
s = (v - min(min(r,g),b));

z = ~s;
s = s + z;
k = find(r == v);
h(k) = (g(k) - b(k))./s(k);
k = find(g == v);
h(k) = 2 + (b(k) - r(k))./s(k);
k = find(b == v);
h(k) = 4 + (r(k) - g(k))./s(k);
h = h/6;
k = find(h < 0);
h(k) = h(k) + 1;
h=(~z).*h;

k = find(v);
s(k) = (~z(k)).*s(k)./v(k);
k = find(~v);
s(k) = 0;

if nargout<=1,
  if (threeD || nargin==3),
    h = reshape(h,siz);
    s = reshape(s,siz);
    v = reshape(v,siz);
    h=cat(3,h,s,v);
  else
    h=[h s v];
  end
else
  h = reshape(h,siz);
  s = reshape(s,siz);
  v = reshape(v,siz);
end