cmap_grad

 Make gradation color map from two color
  C = cmap_grad(chigh,clow,Nlevel)
    returns colormap matrix
  cmap_grad(chigh,clow,Nlevel)
    set colormap
 --- Input
 chigh : color corresponding to max value
 clow  : color corresponding to min value
 Nlevel : number of levels in colormap
 --- Output
 C : colormap matrix ([R G B] matix) : [Nlevel x 3]

 Masa-aki Sato 2008-8-1

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function C = cmap_grad(chigh,clow,Nlevel)
0002 % Make gradation color map from two color
0003 %  C = cmap_grad(chigh,clow,Nlevel)
0004 %    returns colormap matrix
0005 %  cmap_grad(chigh,clow,Nlevel)
0006 %    set colormap
0007 % --- Input
0008 % chigh : color corresponding to max value
0009 % clow  : color corresponding to min value
0010 % Nlevel : number of levels in colormap
0011 % --- Output
0012 % C : colormap matrix ([R G B] matix) : [Nlevel x 3]
0013 %
0014 % Masa-aki Sato 2008-8-1
0015 %
0016 % Copyright (C) 2011, ATR All Rights Reserved.
0017 % License : New BSD License(see VBMEG_LICENSE.txt)
0018 
0019 if length(chigh) ~= 3, error('Color must be 3 vector'); end;
0020 if length(clow) ~= 3,  error('Color must be 3 vector'); end;
0021 
0022 chigh = chigh(:)';
0023 clow  = clow(:)';
0024 
0025 if nargin<3, Nlevel=100; end;
0026 
0027 step=1/(Nlevel-1);
0028 
0029 % gradation
0030 cgrad = [0:step:1]'; 
0031 
0032 % difference of two color
0033 cdif  = chigh - clow;
0034 
0035 % colormap
0036 C = vb_repadd( cgrad * cdif, clow);
0037 
0038 if nargout==0
0039     colormap(C);
0040 end