Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / im2bw.m

diff --git a/octave_packages/image-1.0.15/im2bw.m b/octave_packages/image-1.0.15/im2bw.m
new file mode 100644 (file)
index 0000000..fd96d16
--- /dev/null
+++ b/octave_packages/image-1.0.15/im2bw.m
@@ -0,0 +1,72 @@
+## Copyright (C) 2000  Kai Habel
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{BW}= im2bw (@var{I},threshold)
+## @deftypefnx {Function File} @var{BW}= im2bw (@var{X},@var{cmap},threshold)
+## Converts image data types to a black-white (binary) image.
+## The treshold value should be in the range [0,1].
+## @end deftypefn
+
+## Author:     Kai Habel <kai.habel@gmx.de>
+## Date:       19. March 2000
+
+function BW = im2bw (img, a, b)
+  if (nargin < 2 || nargin > 3)
+    usage("im2bw: number of arguments must be 2 or 3");
+  endif
+  
+  ## Convert img to gray scale
+  if (isrgb(img))
+    img = rgb2gray(img);
+    if (nargin != 2)
+      error("im2bw: two input arguments must be given when the image is a color image");
+    endif
+    t = a;
+  elseif (isind (img) && ismatrix(a) && columns (a) == 3)
+    img = ind2gray (img, a);
+    if (nargin != 3)
+      error("im2bw: three input arguments must be given when the image is indexed");
+    endif
+    t = b;
+  elseif (isgray(img))
+    if (nargin != 2)
+      error("im2bw: two input arguments must be given when the image is gray scale");
+    endif
+    t = a;
+  else
+    error ("im2bw: first input argument must be an image");
+  endif
+
+  ## Do the thresholding
+  if (isscalar (t))
+    if (t < 0 || t > 1)
+      error("im2bw: threshold must be in the interval [0, 1]");
+    endif
+    switch (class(img))
+      case {"double", "single"}
+        BW = (img >= t);
+      case {"uint8"}
+        BW = (img >= 255*t);
+      case {"uint16"}
+        BW = (img >= 65535*t);
+      otherwise
+        error("im2bw: unsupport image class");
+    endswitch
+  else
+    error ("im2bw: threshold value must be scalar");
+  endif
+
+endfunction