# HG changeset patch
# User pkienzle
# Date 1118624458 0
# Node ID 041a707da00b628e48d5f400ce8733b3730fb1b3
# Parent  6c2904b650c9910e0f359059f7357058073eec53
[for Soren Hauberg] new image manipulation functions

diff --git a/bwarea.m b/bwarea.m
new file mode 100644
--- /dev/null
+++ b/bwarea.m
@@ -0,0 +1,57 @@
+## Copyright (C) 2005 Søren Hauberg
+## 
+## 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, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{total}= bwarea(@var{bw})
+## Estimates the area of the "on" pixels of @var{bw}.
+## If @var{bw} is a binary image "on" pixels are defined as pixels
+## valued 1. If @var{bw} is a grayscale image "on" pixels is defined
+## as pixels with values larger than zero.
+## This algorithm is not the same as counting the number of "on"
+## pixels as it tries to estimate the area of the original object
+## and not the image object.
+## @end deftypefn
+
+## Author: Søren Hauberg <hauberg at gmail dot com>
+## 
+## 2005-06-05 Søren Hauberg <hauberg at gmail dot com>
+## * Initial revision
+
+
+function total = bwarea(bw)
+  if (isgray(bw))
+    bw = (bw > 0);
+  endif
+
+  if (!isbw(bw))
+    error("input image muste be either binary or gray scale.\n");
+  endif
+  
+  four = ones(2);
+  two  = diag([1 1]);
+
+  fours = conv2(bw, four);
+  twos  = conv2(bw, two);
+
+  nQ1 = sum(fours(:) == 1);
+  nQ3 = sum(fours(:) == 3);
+  nQ4 = sum(fours(:) == 4);
+  nQD = sum(fours(:) == 2 & twos(:) != 1);
+  nQ2 = sum(fours(:) == 2 & twos(:) == 1);
+
+  total = 0.25*nQ1 + 0.5*nQ2 + 0.875*nQ3 + nQ4 + 0.75*nQD;
+  
+endfunction
diff --git a/imresize.m b/imresize.m
new file mode 100644
--- /dev/null
+++ b/imresize.m
@@ -0,0 +1,104 @@
+## Copyright (C) 2005 Søren Hauberg
+## 
+## 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, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{B}= imresize (@var{A}, @var{m})
+## Scales the image @var{A} by a factor @var{m} using nearest neighbour
+## interpolation. If @var{m} is less than 1 the image size will be reduced,
+## and if @var{m} is greater than 1 the image will be enlarged. If the image
+## is being enlarged the it will be convolved with a 11x11 Gaussian FIR filter
+## to reduce aliasing. See below on how to alter this behavior.
+##
+## @deftypefnx {Function File} @var{B}= imresize (@var{A}, @var{m}, @var{method})
+## Same as above except @var{method} interpolation is performed instead of
+## using nearest neighbour. @var{method} can be any method supported by interp2.
+##
+## @deftypefnx {Function File} @var{B}= imresize (@var{A}, [@var{mrow} @var{mcol}])
+## Scales the image @var{A} to be of size @var{mrow}x@var{mcol} using nearest
+## neighbour interpolation. If the image is being enlarged it will be convolved
+## with a lowpass FIR filter as described above.
+##
+## @deftypefnx {Function File} @var{B}= imresize (@var{A}, [@var{mrow} @var{mcol}], @var{method})
+## Same as above except @var{method} interpolation is performed instead of using
+## nearest neighbour. @var{method} can be any method supported by interp2.
+##
+## @deftypefnx {Function File} @var{B}= imresize (..., @var{method}, @var{fsize})
+## If the image the image is being enlarged it will usually be convolved with
+## a 11x11 Gaussian FIR filter. By setting @var{fsize} to 0 this will be turned
+## off, and if @var{fsize} > 0 the image will be convolved with a @var{fsize}
+## by @var{fsize} Gaussian FIR filter.
+##
+## @deftypefnx {Function File} @var{B}= imresize (..., @var{method}, @var{filter})
+## If the image size is being reduced and the @var{filter} argument is passed to 
+## imresize the image will be convolved with @var{filter} before the resizing
+## takes place.
+##
+## @seealso{interp2}
+## @end deftypefn
+
+## Author: Søren Hauberg <hauberg at gmail dot com>
+## 
+## 2005-04-14 Søren Hauberg <hauberg at gmail dot com>
+## * Initial revision
+
+function [ ret ] = imresize (im, m, method, filter)
+  if (!isgray(im))
+    error("The first argument has to be a gray-scale image.");
+  endif
+  [row col] = size(im);
+
+  # Handle the argument that describes the size of the result
+  if (length(m) == 1)
+    new_row = round(row*m);
+    new_col = round(col*m);
+  elseif (length(m) == 2)
+    new_row = m(1);
+    new_col = m(2);
+    m = min( new_row/row, new_col/col );
+  else
+    error("Bad second argument");
+  end
+
+  # Handle the method argument
+  if (nargin < 3)
+    method = "nearest";
+  endif
+
+  # Handle the filterargument
+  if (!strcmp(method, "nearest"))
+    if (nargin < 4)
+      filter = 11;
+    endif
+    if (m > 1 & filter > 0)
+      # If the image is being enlarged and filter > 0 then
+      # convolve the image with a filter*filter gaussian.
+      mu = round(filter/2);
+      sigma = mu/3;
+      x = 1:filter;
+      gauss = 1/sqrt(2*pi*sigma^2) * exp( (-(x-mu).^2)/(2*sigma^2) );
+      im = conv2(gauss, gauss, im, "same");
+    elseif (m < 1 & nargin == 4)
+      # If the image size is being reduced and a fourth argument
+      # is given, use it as a FIR filter.
+      im = conv2(im, filter, "same");
+    endif
+  endif
+  
+  # Perform the actual resizing
+  [XI YI] = meshgrid( linspace(1,col,new_col), linspace(1,row,new_row) );
+  ret = interp2(im, XI, YI, method);
+
+endfunction