Mercurial > octave
view scripts/image/hsv.m @ 31246:43a6be589387
doc: New documentation for memoization techniques (bug #60860)
vectorize.texi: New section on memoization
octave.texi: List new section
author | Arun Giridhar <arungiridhar@gmail.com> |
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date | Thu, 29 Sep 2022 20:31:52 -0400 |
parents | 5d3faba0342e |
children | 597f3ee61a48 |
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######################################################################## ## ## Copyright (C) 1999-2022 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{map} =} hsv () ## @deftypefnx {} {@var{map} =} hsv (@var{n}) ## Create color colormap. This colormap begins with red, changes through ## yellow, green, cyan, blue, and magenta, before returning to red. ## ## It is useful for displaying periodic functions. The map is obtained by ## linearly varying the hue through all possible values while keeping constant ## maximum saturation and value. The equivalent code is ## @code{hsv2rgb ([(0:N-1)'/N, ones(N,2)])}. ## ## The argument @var{n} must be a scalar. ## If unspecified, the length of the current colormap, or 64, is used. ## @seealso{colormap} ## @end deftypefn function map = hsv (n) if (nargin == 1) if (! isscalar (n)) error ("hsv: N must be a scalar"); endif n = double (n); else hf = get (0, "currentfigure"); if (! isempty (hf)) n = rows (get (hf, "colormap")); else n = 64; endif endif if (n == 1) map = [1, 0, 0]; elseif (n > 1) hue = [0:n-1]' / n; map = hsv2rgb ([hue, ones(n,1), ones(n,1)]); else map = zeros (0, 3); endif endfunction ## A better demo of this colormap would be to plot the hsv values. %!demo %! ## Show the 'hsv' colormap profile and as an image %! cmap = hsv (256); %! subplot (2, 1, 1); %! rgbplot (cmap, "composite"); %! subplot (2, 1, 2); %! rgbplot (cmap);