function photo = imread_pct(fingerprint_file)
% imread_pct.m
% load a fingerprint from a ".pct" file,
% such as the ones in
%   ftp://sequoyah.ncsl.nist.gov/pub/databases/data/prints9.tar.Z
% .
% Usage:
%   photo = imread_pct('H:\compression\compression\nist\f0000001.pct');
%   image(photo);
%   colormap(gray(256))
%   axis equal
%   axis tight
% `fingerprint_file' must be the *full* path+filename of a ".pct" file.
% FIXME: this should really be merged into the IMREAD
% routine, to automatically detect '.pct' files.
% See also IMREAD, IMREAD_FITS.

% change log:
% 1999-05-13:DAV: started (based on my imread_fits.m).
% David Cary <d.cary at ieee.org>

% open the file
% if the images look funny, omit the ieee-be flag

fp = fopen(fingerprint_file,'r','ieee-be');


if(fp==-1)
    error(['Can''t open the file ' fingerprint_file ' in imread_pct.m']);
else
   
   header_string = char(fread(fp, 8, 'char')');
   expected_header_string = zeros(1,8);
   expected_header_string(1:3) = '288';
   expected_header_string = char(expected_header_string);
   
   if(~strncmp(expected_header_string, header_string, 8))
      error([...
            '??? Error using ==> imread_pct\n'...
            'Unable to determine the file format\n'...
            '['...
            fingerprint_file ...
            '] Not in fingerprint format.'...
         ])
   else
      [header_length] = sscanf(header_string, '%i')
      s = char(fread(fp, header_length, 'char')')
      
      width = sscanf(s((106+1):(106+8)), '%i');
      height = sscanf(s((106+1+8):(106+8+8)), '%i');
      [bits_per_pixel] = sscanf(s((106+1+8+8):(106+8+8+8)), '%i');
      compression_code =  sscanf(s((106+1+8+8+8+8):(106+8+8+8+8+8)), '%i');
      
        % s = char(fread(fp, 80, 'char')');
        % disp(['[' s ']'])
        % s = char(fread(fp, 80, 'char')');
        % disp(['[' s ']'])
        % datastart = ftell(fp);
        
        if( ~isequal( 8, bits_per_pixel ) )
            bits_per_pixel
            error([...
               'Sorry -- reading this type of image not yet implemented.\n',...
            	'Check (d.cary at ieee.org) for a later version.']);
         end
         if( ~isequal( 0, compression_code ) )
            error([...
               'Sorry -- reading compressed image not yet implemented.\n',...
               'Check (d.cary at ieee.org) for a later version.']);
         end
         
        % photo=zeros(height, width);
        
        % Assumes 8 bits per pixel.
        % Transpose needed to make it look right on screen.
        % fseek(fp, datastart, 'bof');
        photo = uint8(fread(fp,[width height],'uint8'))';
        
        
    end;
    fclose(fp);
    
end

% end imread_pct.m