Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/image-1.0.15/imhist.m b/octave_packages/image-1.0.15/imhist.m
new file mode 100644 (file)
index 0000000..768d3c7
--- /dev/null
+++ b/octave_packages/image-1.0.15/imhist.m
@@ -0,0 +1,71 @@
+## Copyright (C) 1999,2000  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} {} imhist (@var{I},@var{n})
+## @deftypefnx {Function File} {} imhist (@var{I})
+## @deftypefnx {Function File} {} imhist (@var{X},@var{cmap})
+## @deftypefnx {Function File} {[@var{n,x}] = } imhist (...)
+## Shows the histogram of an image using hist.
+## @seealso{hist}
+## @end deftypefn
+
+## Author:     Kai Habel <kai.habel@gmx.de>
+## July 2000 : Paul Kienzle code simplification for hist() call.
+
+function [varargout] = imhist (I, b)
+
+  if (nargin < 1 || nargin > 2)
+    print_usage();
+  endif
+
+  b_is_colormap = 0;
+
+  if (nargin == 2)
+    if (ismatrix (b))
+      b_is_colormap = (columns (b) == 3);
+    endif
+  endif
+
+  if (b_is_colormap)
+    ## assuming I is an indexed image
+    ## b is colormap
+    max_idx = max (max (I));
+    bins = rows (b);
+    if (max_idx > bins)
+      warning ("largest index exceedes length of colormap");
+    endif
+  else
+    ## assuming I is an intensity image
+    ## b is number of bins
+    if (nargin == 1)
+      bins = 256;
+    else
+      bins = b;
+    endif
+
+    ## scale image to range [0,1]
+    I = mat2gray (I);
+  endif
+  
+  if (nargout == 2)
+    [nn,xx] = hist (I(:), bins);
+    vr_val_cnt = 1; varargout{vr_val_cnt++} = nn;
+    varargout{vr_val_cnt++} = xx;
+  else
+    hist (I(:), bins);
+  endif
+
+endfunction