time   calls  line
                  1 function [format,fmt_s] = imftype(filename)
                  2 %IMFTYPE Determine image file format.
                  3 %   [FORMAT,REGISTRY] = IMFTYPE(FILENAME) attempts to determine the image
                  4 %   file format for the file FILENAME.  If IMFTYPE is successful,
                  5 %   FORMAT will be returned as the first string in the ext field
                  6 %   of the format registry (e.g., 'jpg', 'png', etc.)
                  7 %
                  8 %   FORMAT will be an empty string if IMFTYPE cannot determine
                  9 %   the file format.
                 10 %   
                 11 %   REGISTRY is a structure containing all of the values in
                 12 %   the file format registry.  The fields in this structure are:
                 13 %
                 14 %        ext         - A cell array of file extensions for this format
                 15 %        isa         - Function to determine if a file "IS A" certain type
                 16 %        info        - Function to read information about a file
                 17 %        read        - Function to read image data a file
                 18 %        write       - Function to write MATLAB data to a file
                 19 %        alpha       - 1 if the format has an alpha channel, 0 otherwise
                 20 %        description - A text description of the file format
                 21 %
                 22 %   See also IMREAD, IMWRITE, IMFINFO, IMFORMATS.
                 23 
                 24 %   Copyright 1984-2007 The MathWorks, Inc.
                 25 %   $Revision: 1.1.6.4 $  $Date: 2007/11/09 20:34:28 $
                 26 
             4   27 error(nargchk(1, 1, nargin, 'struct')); 
                 28 
                 29 % Optimization:  look for a filename extension as a clue for the
                 30 % first format to try.
                 31 
             4   32 idx = find(filename == '.'); 
             4   33 if (~isempty(idx)) 
             4   34     extension = lower(filename(idx(end)+1:end)); 
                 35 else
                 36     extension = '';
                 37 end
                 38 
                 39 % Try to get useful imformation from the extension.
                 40 
             4   41 if (~isempty(extension)) 
                 42     
                 43     % Look up the extension in the file format registry.
  0.08       4   44     fmt_s = imformats(extension); 
                 45     
             4   46     if (~isempty(fmt_s)) 
                 47     
                 48         if (~isempty(fmt_s.isa))
                 49 
                 50             % Call the ISA function for this format.
                 51             tf = feval(fmt_s.isa, filename);
                 52             
                 53             if (tf)
                 54               
                 55                 % The file is of that format.  Return the ext field.
                 56                 format = fmt_s.ext{1};
                 57                 return;
                 58                 
                 59             end
                 60         end
                 61     end
             4   62 end 
                 63 
                 64 % No useful information was found from the extension. 
                 65 
             4   66 msg = ''; 
                 67 
                 68 % Get all formats from the registry.
  0.01       4   69 fmt_s = imformats; 
                 70 
                 71 % Look through each of the possible formats.
             4   72 for p = 1:length(fmt_s) 
                 73   
                 74     % Call each ISA function until the format is found.
  0.01      76   75     if (~isempty(fmt_s(p).isa)) 
                 76 
  0.02      76   77         tf = feval(fmt_s(p).isa, filename); 
                 78         
            76   79         if (tf) 
                 80           
                 81             % The file is of that format.  Return the ext field.
                 82             format = fmt_s(p).ext{1};
                 83             fmt_s = fmt_s(p);
                 84             return
                 85             
                 86         end
                 87         
                 88     else
                 89       
                 90         msg = ['At least one format does not have an ISA function', ...
                 91                ' registered.  See "help imformats".']; 
                 92         
                 93     end
            76   94 end 
                 95 
                 96 % The file was not of a recognized type.
                 97 
                 98 % Issue the warning, if there is one.
             4   99 if (~isempty(msg)) 
                100     warning('MATLAB:imftype:missingIsaFunction', '%s', msg)
                101 end
                102 
                103 % Return empty value
             4  104 format = ''; 
             4  105 fmt_s = '';