Mercurial > hg > octave-lyh
changeset 14274:727b74f512af
colorcube.m: Add new colormap which maximizes equally spaced colors.
colorcube.m: New file.
NEWS: Add colorcube to list of new functions in 3.8.
scripts/image/module.mk: Add colorcube to build system.
image.txi: Add colorcube to documentation.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Sat, 28 Jan 2012 08:26:51 -0800 |
| parents | bedccd0abe39 |
| children | 311d6346a4d5 |
| files | NEWS doc/interpreter/image.txi scripts/image/colorcube.m scripts/image/module.mk |
| diffstat | 4 files changed, 100 insertions(+), 0 deletions(-) [+] |
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--- a/NEWS +++ b/NEWS @@ -3,6 +3,7 @@ ** Other new functions added in 3.8.0: + colorcube lines rgbplot
--- a/doc/interpreter/image.txi +++ b/doc/interpreter/image.txi @@ -133,6 +133,8 @@ @DOCSTRING(bone) +@DOCSTRING(colorcube) + @DOCSTRING(cool) @DOCSTRING(copper)
new file mode 100644 --- /dev/null +++ b/scripts/image/colorcube.m @@ -0,0 +1,96 @@ +## Copyright (C) 2012 Rik Wehbring +## +## 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} =} colorcube () +## @deftypefnx {Function File} {@var{map} =} colorcube (@var{n}) +## Create color colormap. This colormap is composed of as many equally +## spaced colors (not grays) in the RGB color space as possible. If there +## are not a perfect number @var{n} of regularly spaced colors then the +## remaining entries in the colormap are gradients of pure red, green, blue, +## and gray. +## 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 = colorcube (n) + + if (nargin == 0) + n = rows (colormap); + elseif (nargin == 1) + if (! isscalar (n)) + error ("colorcube: argument must be a scalar"); + endif + else + print_usage (); + endif + + if (n < 9) + map = gray (n); + return; + endif + + # Create colorcube of evenly spaced points with side length of n^1/3 + cubelen = fix (cbrt (n)); + reserve = n - cubelen^3; + + if (reserve == 0) + # Steal space from blue to put the gray gradient + [r, g, b] = meshgrid (linspace (0,1,cubelen), + linspace (0,1,cubelen), + linspace (0,1,cubelen-1)); + else + [r, g, b] = meshgrid (linspace (0,1,cubelen), + linspace (0,1,cubelen), + linspace (0,1,cubelen)); + endif + + # Create map and weed out grays + map = [r(:), g(:), b(:)]; + idx = any (bsxfun (@ne, map(:, 1), map(:, 2:3)), 2); + map = map(idx, :); + + # Weed out pure colors + idx = sum (map == 0, 2); + map = map(idx != 2, :); + + # Put in remaining gradients of pure red, green, blue, and gray + reserve = n - rows (map) - 1; + csteps = fix (reserve/4); + cstepsz = 1 / csteps; + cgrad = (cstepsz:cstepsz:1)'; + gsteps = reserve - 3*csteps; + gstepsz = 1 / gsteps; + ggrad = (gstepsz:gstepsz:1)'; + map = [map + cgrad, zeros(csteps, 1), zeros(csteps, 1) + zeros(csteps, 1), cgrad, zeros(csteps, 1) + zeros(csteps, 1), zeros(csteps, 1), cgrad + 0, 0, 0 + ggrad, ggrad, ggrad]; + +endfunction + + +%!demo +%! ## Show the 'colorcube' colormap as an image +%! image (1:64, linspace (0, 1, 64), repmat ((1:64)', 1, 64)); +%! axis ([1, 64, 0, 1], "ticy", "xy"); +%! colormap (colorcube (64)); +