% showgimg.m
% show a matrix as a grey level image
% usage: showgimg(A,numcol,rng,X,Y)
% X = image matrix,  numcol = # greylevels
% rng = range of matrix entries to show,
%       matrix entries below and above the range are clipped 
%       to black  and white respectively
% X,Y   two element vectors showing the X and Y ranges respectively.   

function y=showgimg(A,numcol,rng,X,Y)
   mn = min(min(A));
   mx = max(max(A));
   Xl = [0.5, 0.5+size(A,2)];
   Yl = [0.5, 0.5+size(A,1)];
   if (nargin > 2)
      if (length(rng) > 1) 
          mn = rng(1); mx = rng(2);
          end;
      end;
   if (nargin >3) 
      if length(X) > 1 Xl=X; end;
      if length(Y) > 1 Yl=Y; end;
      end;   
   s = numcol-1;
   colormap(((0:s)/s)'*[1,1,1]);
   axis('image') 
   img = ((numcol+1)/(mx-mn))*(A-mn*ones(size(A)));
   image(Xl,Yl,img);