function y =  mmreadgray( filename )
%  MMREADGRAY Read an image from a commercial file format and stores it as a gray-scale image.
%
%  Y =  MMREADGRAY( FILENAME )
%
%  Input:
%    FILENAME - String. Name of file. Possible extensions: tif, hdf,
%        jpg, bmp, pcx, xwd.
%
%  Output:
%    Y - Gray-scale (uint8 or uint16) or binary image (logical uint8).
%
%  MMIMREAD reads the image in FILENAME and stores it in Y,  an uint8
%    gray-scale image (without colormap). If the input file is a color
%    image, it is converted to gray-scale. This function calls the
%    MATLAB function IMREAD.
%
%  Examples
%  --------
%
%  a=mmreadgray('small_bw.tif');
%  mmshow(a)
%
%  See also MMWRITE.

% begin of the default argument automatic treatment
% end of the default argument automatic treatment 1

[xin map] = imread(filename);

% if there is no map, then nothing to do
if isempty(map)
  if (size(xin,3) == 1)     % normal gray scale without colormap
    y = xin;
    return;
  elseif (size(xin,3) == 3) % true-color RGB image
    if all(all(((xin(:,:,1) == xin(:,:,2)) & (xin(:,:,1) == xin(:,:,2)))))
      y = xin(:,:,1);
      return;
    else
      disp('Warning: converting true-color RGB image to gray');
      if isa(xin, 'uint8')
        y = uint8(0.2989 * double(xin(:,:,1)) + ...
                  0.5870 * double(xin(:,:,2)) + ...
                  0.1140 * double(xin(:,:,3)));
        return;
      else
        y = 0.2989 * xin(:,:,1) + 0.5870 * xin(:,:,2) + 0.1140 * xin(:,:,3);
        return;
      end
    end
  else
    disp('Error: image with unknow number of bands');
  end
end

if isa(xin, 'uint8')
    xin = double(xin)+1;    % Switch to one based indexing
end

if size(map,2) ~= 3
  disp('Error: colormap not of size 3')
  return;
end

% test if colormap is gray
if ~all(map(:,1) == map(:,2) & map(:,1) == map(:,3))
  map = rgb2ntsc(map); % if not, convert
  disp('Warning: converting RGB colored indexed image to gray');
end

if (size(map,1) <= 256)
  y = uint8(zeros(size(xin)));
  y(:) = uint8(map(xin,1) * 255);
  if (size(map,1) == 2  & min(map(:,1)) == 0 & max(map(:,1)) == 1 )
    y = mmbinary(y);
    disp('binary image');
  elseif ~any(map(3:end,:))
    y = mmbinary(y);
    disp('binary image');
  else
    disp('uint8 gray-scale image');
  end
else
  y = uint16(zeros(size(xin)));
  y(:) = uint16(map(xin,1) * 65535);
  disp('uint16 gray-scale image');
end

return;


%  Copyright (c) 1998-2001 by SDC Information Systems.