pr_scaletocmap

 scales image data to colormap, returning colormap indices
 FORMAT [img, badvals]=pr_scaletocmap(inpimg,mn,mx,cmap,lrn)
 
 Inputs
 inpimg     - matrix containing image to scale
 mn         - image value that maps to first value of colormap
 mx         - image value that maps to last value of colormap
 cmap       - 3xN colormap
 lrn        - 1x3 vector, giving colormap indices that should fill:
              - lrn(1) (L=Left) - values less than mn
              - lrn(2) (R=Right) - values greater than mx
              - lrn(3) (N=NaN) - NaN values
             If lrn value is 0, then colormap values are set to 1, and
             indices to these values are returned in badvals (below)
 
 Output
 img        - inpimg scaled between 1 and (size(cmap, 1))
 badvals    - indices into inpimg containing values out of range, as
              specified by lrn vector above
 
 $Id: pr_scaletocmap.m,v 1.1 2005/04/20 15:05:00 matthewbrett Exp $

0001 function [img, badvals]=pr_scaletocmap(inpimg,mn,mx,cmap,lrn)
0002 % scales image data to colormap, returning colormap indices
0003 % FORMAT [img, badvals]=pr_scaletocmap(inpimg,mn,mx,cmap,lrn)
0004 %
0005 % Inputs
0006 % inpimg     - matrix containing image to scale
0007 % mn         - image value that maps to first value of colormap
0008 % mx         - image value that maps to last value of colormap
0009 % cmap       - 3xN colormap
0010 % lrn        - 1x3 vector, giving colormap indices that should fill:
0011 %              - lrn(1) (L=Left) - values less than mn
0012 %              - lrn(2) (R=Right) - values greater than mx
0013 %              - lrn(3) (N=NaN) - NaN values
0014 %             If lrn value is 0, then colormap values are set to 1, and
0015 %             indices to these values are returned in badvals (below)
0016 %
0017 % Output
0018 % img        - inpimg scaled between 1 and (size(cmap, 1))
0019 % badvals    - indices into inpimg containing values out of range, as
0020 %              specified by lrn vector above
0021 %
0022 % $Id: pr_scaletocmap.m,v 1.1 2005/04/20 15:05:00 matthewbrett Exp $
0023 
0024 if nargin <  4
0025   error('Need inpimg, mn, mx, and cmap');
0026 end
0027 
0028 cml = size(cmap,1);
0029 
0030 if nargin < 5
0031   lrn = [1 cml 0];
0032 end
0033 
0034 img = (inpimg-mn)/(mx-mn);  % img normalized to mn=0,mx=1
0035 if cml==1 % values between 0 and 1 -> 1
0036   img(img>=0 & img<=1)=1;
0037 else
0038   img = img*(cml-1)+1;
0039 end
0040 outvals = {img<1, img>cml, isnan(img)};
0041 img= round(img);
0042 badvals = zeros(size(img));
0043 for i = 1:length(lrn)
0044   if lrn(i)
0045     img(outvals{i}) = lrn(i);
0046   else
0047     badvals = badvals | outvals{i};
0048     img(outvals{i}) = 1;
0049   end    
0050 end
0051 return