Mercurial > octave-antonio
view scripts/image/rainbow.m @ 17118:c97a26408ee0
Implement PixelRegion option for imread().
* imread.m: document new option.
* private/__imread__.m: parse new option and set defaults.
* __magick_read__.cc (calculate region): new option to calculate the region
to be read, shifts in memory required, and output image size.
(read_indexed_images, read_images): implement reading of only specific
regions of an image.
(__magick_read__): get octave_scalar_map at start for simplicity.
author | Carnë Draug <carandraug@octave.org> |
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date | Wed, 31 Jul 2013 21:28:48 +0100 |
parents | ac332eb727dd |
children | d63878346099 |
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## 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{map} =} rainbow () ## @deftypefnx {Function File} {@var{map} =} rainbow (@var{n}) ## Create color colormap. This colormap ranges from red through orange, ## yellow, green, blue, to violet. ## The argument @var{n} must be a scalar. ## If unspecified, the length of the current colormap, or 64, is used. ## @seealso{colormap} ## @end deftypefn ## Author: Kai Habel <kai.habel@gmx.de> ## this colormap is not part of matlab, it is like the prism ## colormap map but with a continuous map ## PKG_ADD: colormap ("register", "rainbow"); ## PKG_DEL: colormap ("unregister", "rainbow"); function map = rainbow (n) if (nargin == 0) n = rows (colormap); elseif (nargin == 1) if (! isscalar (n)) error ("rainbow: N must be a scalar"); endif else print_usage (); endif if (n == 1) map = [1, 0, 0]; elseif (n > 1) x = [0:(n-1)]' / (n - 1); r = ( (x < 2/5) + (x >= 2/5 & x < 3/5) .* (-5 * x + 3) + (x >= 4/5) .* (10/3 * x - 8/3)); g = ( (x < 2/5) .* (5/2 * x) + (x >= 2/5 & x < 3/5) + (x >= 3/5 & x < 4/5) .* (-5 * x + 4)); b = ( (x >= 3/5 & x < 4/5) .* (5 * x - 3) + (x >= 4/5)); map = [r, g, b]; else map = zeros (0, 3); endif endfunction %!demo %! ## Show the 'rainbow' colormap as an image %! image (1:64, linspace (0, 1, 64), repmat ((1:64)', 1, 64)); %! axis ([1, 64, 0, 1], "ticy", "xy"); %! colormap (rainbow (64));