% HYSTHRESH - Hysteresis thresholding%% Usage: bw = hysthresh(im, T1, T2)%% Arguments:%             im  - image to be thresholded (assumed to be non-negative)%             T1  - upper threshold value%             T2  - lower threshold value%                   (T1 and T2 can be entered in any order, the larger of the%                   two values is used as the upper threshold)% Returns:%             bw  - the thresholded image (containing values 0 or 1)%% Function performs hysteresis thresholding of an image.% All pixels with values above threshold T1 are marked as edges% All pixels that are connected to points that have been marked as edges% and with values above threshold T2 are also marked as edges. Eight% connectivity is used.% Copyright (c) 1996-2005 Peter Kovesi% School of Computer Science & Software Engineering% The University of Western Australia% http://www.csse.uwa.edu.au/% % Permission is hereby granted, free of charge, to any person obtaining a copy% of this software and associated documentation files (the "Software"), to deal% in the Software without restriction, subject to the following conditions:% % The above copyright notice and this permission notice shall be included in all% copies or substantial portions of the Software.%% The Software is provided "as is", without warranty of any kind.% December 1996  - Original version% March    2001  - Speed improvements made (~4x)% April    2005  - Modified to cope with MATLAB 7's uint8 behaviour% July     2005  - Enormous simplification and great speedup by realizing%                  that you can use bwselect to do all the workfunction bw = hysthresh(im, T1, T2)    if T1 < T2    % T1 and T2 reversed - swap values 	tmp = T1;	T1 = T2; 	T2 = tmp;    end        aboveT2 = im > T2;                     % Edge points above lower                                           % threshold.     [aboveT1r, aboveT1c] = find(im > T1);  % Row and colum coords of points                                           % above upper threshold.					       % Obtain all connected regions in aboveT2 that include a point that has a    % value above T1     bw = bwselect(aboveT2, aboveT1c, aboveT1r, 8);