function y =  mmopentransf( f, type, n )
%  MMOPENTRANSF Open transform.
%
%  Y =  MMOPENTRANSF( F, TYPE, N )
%
%  Input:
%    F - Binary image (logical uint8).
%    TYPE - String. Disk family: 'OCTAGON', 'CHESSBOARD', 'CITY-BLOCK',
%        'LINEAR-V', LINEAR-H'. DEFAULT: 'OCTAGON'.
%    N -  Maximum disk radius. DEFAULT: 65535.
%
%  Output:
%    Y - Gray-scale (uint8 or uint16) image.
%
%  Compute the open transform of a binary image. The value of the
%    pixels in the open transform gives the largest radius of the disk
%    plus 1, where the open by it is not empty at that pixel. The disk
%    sequency must satisfy the following: if r > s, rB is sB-open, i.e.
%    rB open by sB is equal rB.
%
%  Limitation
%  ----------
%  As this function can take quite a long time to execute, there is a
%    printout notifying the status of the execution. The radius of the
%    disk is informed for each open executed.
%
%  Examples
%  --------
%
%  f = logical(uint8([...
%  0     0     0     0     0     0     0     0;...
%  0     0     1     1     1     1     0     0;...
%  0     0     1     1     1     1     1     0;...
%  0     1     0     1     1     1     0     0;...
%  1     1     0     0     0     0     0     0]));
%  mmopentransf( f, 'city-block')
%  mmopentransf( f, 'chessboard')
%  mmopentransf( f, 'linear-h')
%  mmopentransf( f, 'linear-v')
%
%  f=imread('numbers.tif');
%  mmshow(f);
%  g=mmopentransf(f,'OCTAGON');
%  mmshow(g);
%
%
%
%  THE OPEN TRANSFORM STORES ALL THE OPENINGS BY THE DISK WITH RADIUS
%  R
%  b=mmsedisk(3,'2D','OCTAGON');
%  g1=mmopen(f,b);
%  mmshow(g1);
%  g2=mmcmp(g,'>',3);
%  mmis(g1,'==',g2)
%
%  See also MMOPEN, MMPATSPEC, MMSEDISK.

% begin of the default argument automatic treatment

if ~exist('type','var') type = 'OCTAGON'; end

if ~exist('n','var') n = 65535; end
% end of the default argument automatic treatment 1

if (nargin == 0 | nargin > 3)
  disp('Error: 1, 2 or 3 input parameters');
  return;
end
if ~mmisbinary(f)
  disp('Error: input image is not binary');
  return;
end
type = upper(type);
if (strcmp(type,'OCTAGON')    | ...
    strcmp(type,'CHESSBOARD') | ...
    strcmp(type,'CITY-BLOCK') )
  flag = 0;
elseif  strcmp(type,'LINEAR-H')
  se = mmimg2se(logical(uint8([1 1 1])));
  flag = 1;
elseif  strcmp(type,'LINEAR-V')
  se = mmimg2se(logical(uint8([1;1;1])));
  flag = 1;
else
  disp('Error: only accepts OCTAGON, CHESSBOARD, CITY-BLOCK, LINEAR-H, or LINEAR-V as type');
  return;
end
k=0;
y=uint16(zeros(size(f)));
a=logical(uint8(1));
z=logical(uint8(0));
while ~(mmisequal(a,z) | (k>=n))
     fprintf('\rprocessing r=%3.0f',k);
     if flag
       a=mmopen(f,mmsesum(se,k));
     else
       a=mmopen(f,mmsedisk(k,'2D',type));
     end
     y=mmaddm(y, mmgray(a,'uint16',1));
     k=k+1;
end
fprintf('\n');


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