Mercurial > octave-nkf
view scripts/image/cubehelix.m @ 19647:e8e3a89fa370
Fix colormap functions when N is not of class double (bug #44070)
* autumn.m, bone.m, cool.m, copper.m, cubehelix.m, gray.m, hsv.m, ocean.m,
rainbow.m, spring.m, summer.m, winter.m: cast N to double since in this
colormap functions, N is used directly used in the operations and ends up
casting colormap to something else. Note that a colormap MUST be of class
double. Also, if N is an integer class, all values in colormap end up 0
or 1. Also simplify code for input checking by declaring default on function
signature line.
* flag.m, gmap40.m, hot.m, jet.m, lines.m, pink.m, prism.m, white.m: simplify
input check like the other colormap functions.
* test/colormaps.tst: add new test file to test all colormaps at once.
* test/Makefile.am: add new test file to build system.
used to create the colormap and if less
author | Carnë Draug <carandraug@octave.org> |
---|---|
date | Fri, 23 Jan 2015 15:37:56 +0000 |
parents | ed4eeb4314e6 |
children | 4197fc428c7d |
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## Copyright (C) 2014 Carnë Draug ## ## 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{map} =} cubehelix () ## @deftypefnx {Function File} {@var{map} =} cubehelix (@var{n}) ## Create cubehelix colormap. ## ## This colormap varies from black to white going though blue, green, and red ## tones while maintaining a monotonically increasing perception of intensity. ## This is achieved by transversing a color cube from black to white through ## a helix, hence the name cubehelix, while taking into account the perceived ## brightness of each channel according to the NTSC specifications from 1953. ## ## @example ## rgbplot (cubehelix (256)) ## @end example ## ## The argument @var{n} must be a scalar and corresponds to the lenght of the ## colormap. Defaults to the length of the current colormap. ## ## Development of this colormap is described in @cite{Green, D. A., 2011, ## "A colour scheme for the display of astronomical intensity images", ## Bulletin of the Astronomical Society of India, 39, 289.}. ## ## @seealso{colormap} ## @end deftypefn ## Author: Carnë Draug <carandraug@octave.org> ## PKG_ADD: colormap ("register", "cubehelix"); ## PKG_DEL: colormap ("unregister", "cubehelix"); function map = cubehelix (n = rows (colormap ()), start = 0.5, rots = -1.5, hue = 1, gamma = 1) if (nargin > 5) print_usage () elseif (! isscalar (n)) error ("cubehelix: N must be a scalar"); endif n = double (n); if (n > 1) coeff = [ -0.14861 -0.29227 1.97294 1.78277 -0.90649 0.00000]; fract = ((0:n-1) / (n-1))'; angle = 2 * pi * (start/3 + 1 + rots*fract); fract = fract .^ gamma; amp = hue * fract .* (1-fract) /2; warning ("off", "Octave:broadcast", "local"); map = fract + amp .* ([cos(angle) sin(angle)] * coeff); ## Clip values (only in case users have changed values of hue or gamma) map(map < 0) = 0; map(map > 1) = 1; elseif (n > 0) map = [0, 0, 0]; else map = zeros (0, 3); endif endfunction %!demo %! subplot (1, 2, 1) %! rgbplot (cubehelix (256), "composite") %! subplot (1, 2, 2) %! rgbplot (cubehelix (256))