Mercurial > octave
view scripts/image/jet.m @ 31207:1c40fc2344f4 stable
quad2d.m: Add BIST test to cset b0e90ca8e679 (bug #62972)
* quad2d.m: Add BIST test for bug #62972.
author | Rik <rik@octave.org> |
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date | Sun, 28 Aug 2022 14:19:43 -0700 |
parents | 796f54d4ddbf |
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} =} jet () ## @deftypefnx {} {@var{map} =} jet (@var{n}) ## Create color colormap. This colormap ranges from dark blue through blue, ## cyan, green, yellow, red, to dark red. ## ## The argument @var{n} must be a scalar. ## If unspecified, the length of the current colormap, or 64, is used. ## ## Programming Note: The @code{jet} colormap is not perceptually uniform. ## Try the @code{viridis} colormap if that is important. For a drop-in ## replacement for @code{jet} with better perceptual characteristics try ## the @code{turbo} colormap. ## @seealso{colormap, turbo} ## @end deftypefn function map = jet (n) if (nargin == 1) if (! isscalar (n)) error ("jet: 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 = [0, 1, 1]; elseif (n == 2) map = [0, 0, 1 0, 1, 1]; elseif (n > 2) nel = ceil (n/4); # number of elements idx1 = ceil (3/8 * n) + 1; # ~3/8*n for large n if (mod (n, 8) == 2) idx1 += 1; endif idx2 = idx1 + nel - 1; # ~5/8*n for large n idx3 = min (idx2 + nel, n); # ~7/8*n for large n r = zeros (n, 1); r(idx1:idx2, 1) = [1:nel] / nel; r(idx2:idx3, 1) = 1; nel2 = n - idx3; r(idx3:(idx3+nel2), 1) = [nel:-1:(nel - nel2)] / nel; idx1 = idx1 - nel; # ~1/8*n for large n idx2 = idx1 + nel - 1; # ~3/8*n for large n idx3 = min (idx2 + nel, n); # ~5/8*n for large n g = zeros (n, 1); g(idx1:idx2, 1) = [1:nel] / nel; g(idx2:idx3, 1) = 1; nel2 = min (nel, n - idx3); g(idx3:(idx3+nel2), 1) = [nel:-1:(nel - nel2)] / nel; idx1 = max (idx2 - nel, 1); # ~1/8*n for large n idx2 = idx2; # ~3/8*n for large n idx3 = idx3; # ~5/8*n for large n b = zeros (n, 1); nel2 = min (nel, idx1-1); b(1:idx1, 1) = [(nel - nel2):nel] / nel; b(idx1:idx2, 1) = 1; nel2 = min (nel, n - idx3); b(idx2:(idx2+nel2), 1) = [nel:-1:(nel - nel2)] / nel; map = [r, g, b]; else map = zeros (0, 3); endif endfunction %!demo %! ## Show the 'jet' colormap profile and as an image %! cmap = jet (256); %! subplot (2, 1, 1); %! rgbplot (cmap, "composite"); %! subplot (2, 1, 2); %! rgbplot (cmap);