function image_gray
%IMAGE_GRAY Trasform the image in grayscale (scale I between 0 and 1).
%
%		IMAGE_GRAY
%
%

%
% Copyright (c) 1995 by Claudio Rivetti and Mark Young
% claudio@alice.uoregon.edu,    mark@alice.uoregon.edu
%

global I Oldzrange Oldcontrast Oldoffset Oldmap Undofun

if isempty(I)
  return;
end

if ~isimage
  setviewmode('TOPVIEW');
  showimage;
end

statusbar('Converting image to gray levels...');
Oldzrange=zrange;
Oldcontrast=getcontrast;
Oldoffset=getoffset;
Oldmap=getmap;

zrange([0 1]);
setcontrast(0);
setoffset(0);
setmap(1);
mn=min(min(I));
mx=max(max(I));

setimage((I-mn)/(mx-mn));
Undofun=['global Oldzrange Oldcontrast Oldoffset Oldmap;zrange(Oldzrange);',...
		'setimage(getclipboard,inf,0);setcontrast(Oldcontrast);',...
		'setoffset(Oldoffset);setmap(Oldmap);setclipboard([]);'];
clearstatusbar;

return