update packages

[CreaPhase.git] / octave_packages / m / image / hsv2rgb.m

diff --git a/octave_packages/m/image/hsv2rgb.m b/octave_packages/m/image/hsv2rgb.m
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+## Copyright (C) 1999-2012 Kai Habel
+##
+## This file is part of Octave.
+##
+## Octave 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 3 of the License, or (at
+## your option) any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{rgb_map} =} hsv2rgb (@var{hsv_map})
+## Transform a colormap or image from the HSV space to the RGB space.
+## @seealso{rgb2hsv}
+## @end deftypefn
+
+## Author: Kai Habel <kai.habel@gmx.de>
+## Adapted-by: jwe
+
+function rgb_map = hsv2rgb (hsv_map)
+
+## Each color value x = (r,g,b) is calculated with
+## x = (1-sat)*val+sat*val*f_x(hue)
+## where f_x(hue) is a piecewise defined function for
+## each color with f_r(hue-2/3) = f_g(hue) = f_b(hue-1/3).
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  ## If we have an image convert it into a color map.
+  if (ismatrix (hsv_map) && ndims (hsv_map) == 3)
+    is_image = true;
+    Sz = size (hsv_map);
+    hsv_map = [hsv_map(:,:,1)(:), hsv_map(:,:,2)(:), hsv_map(:,:,3)(:)];
+    ## Convert to a double image.
+    if (isinteger (hsv_map))
+      C = class (hsv_map);
+      low = double (intmin (C));
+      high = double (intmax (C));
+      hsv_map = (double (hsv_map) - low) / (high - low);
+    endif
+  else
+    is_image = false;
+  endif
+
+  if (! ismatrix (hsv_map) || columns (hsv_map) != 3)
+    error ("hsv2rgb: argument must be a matrix of size nx3");
+  endif
+
+  ## set values <0 to 0 and >1 to 1
+  hsv_map = (hsv_map >= 0 & hsv_map <= 1) .* hsv_map \
+      + (hsv_map < 0) .* 0 + (hsv_map > 1);
+
+  ## fill rgb map with v*(1-s)
+  rgb_map = kron ([1, 1, 1], hsv_map(:,3) .* (1 - hsv_map(:,2)));
+
+  ## red(hue-2/3)=green(hue)=blue(hue-1/3)
+  ## apply modulo 1 for red and blue
+  t = hsv_map(:,1);
+  tp = t';
+  hue = [(tp - 2/3 - floor (t - 2/3)');
+         tp;
+         (tp - 1/3 - floor (t - 1/3)')]';
+
+  ## factor s*v -> f
+  f = kron ([1, 1, 1], hsv_map(:,2)) .* kron ([1, 1, 1], hsv_map(:,3));
+
+  ## add s*v* hue-function to rgb map
+  rgb_map = rgb_map +  f .* (6 * (hue < 1/6) .* hue
+                    + (hue >= 1/6 & hue < 1/2)
+                    + (hue >= 1/2 & hue < 2/3) .* (4 - 6 * hue));
+
+  ## If input was an image, convert it back into one.
+  if (is_image)
+    rgb_map = reshape (rgb_map, Sz);
+  endif
+
+endfunction