Mercurial > octave-antonio
view scripts/image/hsv2rgb.m @ 17170:d6499c14021c
doc: Periodic grammarcheck of documentation.
* doc/interpreter/basics.txi, doc/interpreter/expr.txi,
doc/interpreter/install.txi, doc/interpreter/java.txi,
doc/interpreter/plot.txi, doc/interpreter/sparse.txi,
doc/interpreter/vectorize.txi, libinterp/corefcn/cellfun.cc,
libinterp/corefcn/debug.cc, libinterp/corefcn/file-io.cc,
libinterp/corefcn/load-save.cc, libinterp/corefcn/matrix_type.cc,
libinterp/corefcn/pr-output.cc, libinterp/parse-tree/oct-parse.in.yy,
liboctave/numeric/LSODE-opts.in, scripts/image/imformats.m,
scripts/image/imread.m, scripts/image/imwrite.m,
scripts/miscellaneous/error_ids.m, scripts/miscellaneous/fileattrib.m,
scripts/miscellaneous/mex.m, scripts/miscellaneous/mkoctfile.m,
scripts/miscellaneous/warning_ids.m, scripts/prefs/prefdir.m,
scripts/prefs/preferences.m, scripts/signal/fftfilt.m,
scripts/strings/isstrprop.m, scripts/testfun/assert.m:
Periodic grammarcheck of documentation.
author | Rik <rik@octave.org> |
---|---|
date | Sun, 04 Aug 2013 13:08:39 -0700 |
parents | b1cd65881592 |
children | b81b9d079515 |
line wrap: on
line source
## 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}) ## @deftypefnx {Function File} {@var{rgb_img} =} hsv2rgb (@var{hsv_img}) ## Transform a colormap or image from hue-saturation-value (HSV) space to ## red-green-blue (RGB) space. ## ## A color in HSV space is represented by hue, saturation and value ## (brightness) levels. Value gives the amount of light in the color. Hue ## describes the dominant wavelength. Saturation is the amount of hue mixed ## into the color. ## ## A color in the RGB space consists of red, green, and blue intensities. ## @seealso{rgb2hsv, ind2rgb, ntsc2rgb} ## @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 cls = class (hsv_map); if (! any (strcmp (cls, {"uint8", "uint16", "single", "double"}))) error ("hsv2rgb: invalid data type '%s'", cls); elseif (isfloat (hsv_map) && (any (hsv_map(:) < 0) || any (hsv_map(:) > 1))) error ("hsv2rgb: floating point images may only contain values between 0 and 1"); endif ## If we have an image convert it into a color map. if (isreal (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)) low = double (intmin (cls)); high = double (intmax (cls)); hsv_map = (double (hsv_map) - low) / (high - low); endif else is_image = false; endif if (! isreal (hsv_map) || columns (hsv_map) != 3 || issparse (hsv_map)) error ("hsv2rgb: input must be a matrix of size Nx3 or MxNx3"); endif ## FIXME: Currently input is validated and an error results if values ## are outside range [0, 1]. We could also simply allow those values ## and re-instate this code to produce saturating semantics. ## Trim map to range [0, 1] #hsv_map(hsv_map < 0) = 0; #hsv_map(hsv_map > 1) = 1; h = hsv_map(:,1); s = hsv_map(:,2); v = hsv_map(:,3); ## Prefill rgb map with v*(1-s) rgb_map = repmat (v .* (1 - s), 1, 3); ## red = hue-2/3 : green = hue : blue = hue-1/3 ## Apply modulo 1 for red and blue to keep within range [0, 1] hue = [mod(h - 2/3, 1), h , mod(h - 1/3, 1)]; ## factor s*v -> f f = repmat (s .* v, 1, 3); ## add s*v*hue-function to 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)); ## FIXME: hsv2rgb does not preserve class of image. ## Should it also convert back to uint8, uint16 for integer images? ## If input was an image, convert it back into one. if (is_image) rgb_map = reshape (rgb_map, sz); endif endfunction %% Test pure colors %!assert (hsv2rgb ([0 1 1]), [1 0 0]) %!assert (hsv2rgb ([1 1 1]), [1 0 0]) %!assert (hsv2rgb ([1/3 1 1]), [0 1 0]) %!assert (hsv2rgb ([2/3 1 1]), [0 0 1]) %!test %! hsv_map = rand (64, 3); %! assert (rgb2hsv (hsv2rgb (hsv_map)), hsv_map, 1e-6); %!test %! hsv_img = rand (64, 64, 3); %! assert (rgb2hsv (hsv2rgb (hsv_img)), hsv_img, 1e-6); %% Test input validation %!error hsv2rgb () %!error hsv2rgb (1,2) %!error <invalid data type> hsv2rgb ({1}) %!error <must be a matrix of size Nx3> hsv2rgb (ones (2,2)) %!error <must be a matrix of size Nx3> hsv2rgb (sparse (ones(1,3)))