function [X,map,out3]=bmpread(filename);

%BMPREAD Read a BMP (Microsoft Windows Bitmap) file from disk.

%	[X,MAP]=BMPREAD('filename') reads the file 'filename' and

%	returns the indexed image X and associated colormap

%	MAP. If no extension is given for the filename, the

%	extension '.bmp' is assumed.

%	[R,G,B]=BMPREAD('filename') reads the 24-bit BMP file

%	from the file 'filename'.

%	BPP=BMPREAD('filename') returns the number of bits per

%	pixel in the BMP file.

%

%	BMPREAD does not read 1-bit or compressed BMP files.

%

%	See also: BMPWRITE, GIFREAD, HDFREAD, PCXREAD, TIFFREAD,

%	          XWDREAD.



%	Mounil Patel 3/10/94

%	Revised Steve Eddins February 9, 1995

%	Copyright (c) 1994 by The MathWorks, Inc.

%	$Revision: 1.14 $  $Date: 1996/06/14 12:39:07 $





if (nargin~=1)

	error('Requires a filename as an argument.');

end;



if (isstr(filename)~=1)

	error('Requires a string filename as an argument.');

end;



if (isempty(findstr(filename,'.'))==1)

	filename=[filename,'.bmp'];

end;



fid=fopen(filename,'rb','l');

if (fid==-1)

	error(['Error opening ',filename,' for input.']);

end;



bfType=fread(fid,2,'uchar');

if (bfType~=[66;77])

	fclose(fid);

	error('Not a BMP file.');

end;



bfSize=fread(fid,1,'uint');

bfReserved1=fread(fid,1,'ushort');

bfReserved2=fread(fid,1,'ushort');

bfOffBytes=fread(fid,1,'uint');



biSize=fread(fid,1,'uint');

if (biSize~=40)

	fclose(fid);

	error('Not a MS Windows Device Independent Bitmap BMP file.');

end;



biWidth=fread(fid,1,'uint');

biHeight=fread(fid,1,'uint');

biPlanes=fread(fid,1,'ushort');

biBitCount=fread(fid,1,'ushort');

if (biBitCount == 1)

  error('BMPREAD does not read 1-bit BMP files.');

end

biCompression=fread(fid,1,'uint');

if biCompression~=0 

	error('Can''t load compressed format bitmaps.');

end;

biSizeImage=fread(fid,1,'uint');

biXPels=fread(fid,1,'uint');

biYPels=fread(fid,1,'uint');

biClrUsed=fread(fid,1,'uint');

biClrImportant=fread(fid,1,'uint');



if (nargout <= 1)

  X = biBitCount;

  map = [];

  fclose(fid);

  return;

end



if ((nargout == 2) & (biBitCount == 24))

  error('Three output arguments required for 24-bit BMP file.');

end



if ((nargout == 3) & (biBitCount < 24))

  error('Only two arguments needed for 4- and 8-bit BMP files.');

end



if (biBitCount == 24)

  if (rem(biWidth,4)~=0)

    XSize=biWidth+(4-rem(biWidth,4));

  else

    XSize=biWidth;

  end

  YSize=biHeight;

  Size=XSize*YSize;



  fseek(fid, bfOffBytes, 'bof');

  X=fread(fid,Size*3,'uchar');

  out3 = rot90(reshape(X(1:3:length(X)), XSize, YSize)) * (1/255);

  map = rot90(reshape(X(2:3:length(X)), XSize, YSize)) * (1/255);

  X = rot90(reshape(X(3:3:length(X)), XSize, YSize)) * (1/255);

  if (rem(biWidth,4)~=0)

    X=X(:,1:biWidth);

    map = map(:,1:biWidth);

    out3 = out3(:,1:biWidth);

  end;

  

  fclose(fid);

  return;

end  



if (biClrUsed==0)

	nColors=2.^biBitCount;

else

	nColors=biClrUsed;

end;



% load color map now

if (biClrUsed>256)

	map=[];	% 24-bit images have no colormap

else

	map=fread(fid,4*nColors,'uchar');

	map=reshape(map,4,nColors);

	map=map';

	map=map(:,1:3);

	map=fliplr(map);

end;



map=map./255;



% read in 8-bit image data

if (biBitCount==8)

	if (rem(biWidth,4)~=0)

		XSize=biWidth+(4-rem(biWidth,4));

	else

		XSize=biWidth;

	end

	YSize=biHeight;

	Size=XSize*YSize;



	fseek(fid, bfOffBytes, 'bof');

	X=fread(fid,Size,'uchar');

	X=reshape(X,XSize,YSize);

	X=rot90(X);

	X=X+1;

	if (rem(biWidth,4)~=0)

		X=X(:,1:biWidth);

	end;

end;



if (biBitCount==4)

	XSize=ceil(biWidth/2);

	if (rem(XSize,4)~=0)

		XSize=XSize+rem(XSize,4);

	end;

	YSize=biHeight;

	Size=XSize*YSize;

	fseek(fid, bfOffBytes, 'bof');

	X=fread(fid,Size,'uchar');

	X=reshape(X,XSize,YSize);

	X=X';

	loX=X;



	index=loX>127;

	loX(index)=loX(index)-128;

	index=loX>63;

	loX(index)=loX(index)-64;

	index=loX>31;

	loX(index)=loX(index)-32;

	index=loX>15;

	loX(index)=loX(index)-16;



	X=X-loX;

	X=X./16;

	[m,n]=size(X);

	X(:,1:2:(n*2))=X;

	X(:,2:2:(n*2))=loX;

	X=flipud(X);

	X=X+1;

end;



cmax=max(max(X));

map=map(1:cmax,:);



fclose(fid);