Mercurial > octave
view scripts/image/rgb2ind.m @ 17990:a40156e8b6a7
rgb2ind: backout 5d6243c2acbf removing all quantization (bug #40669)
* rgb2ind.m: remove the options n, tol, map, and dither which were implemented
by creating tif file, making a system call to gm convert, and reading back the
new file. This removes all quantization options limiting rgb2ind to create
indexed images equal to the input RGB image and a colormap with as many colors
as the input image.
author | Carnë Draug <carandraug@octave.org> |
---|---|
date | Sat, 23 Nov 2013 23:43:51 +0000 |
parents | d63878346099 |
children | b8cd17571a1d |
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## Copyright (C) 1994-2013 John W. Eaton ## Copyright (C) 2012 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{x}, @var{map}] =} rgb2ind (@var{rgb}) ## @deftypefnx {Function File} {[@var{x}, @var{map}] =} rgb2ind (@var{R}, @var{G}, @var{B}) ## Convert an image in red-green-blue (RGB) color space to an indexed image. ## ## @seealso{ind2rgb, rgb2hsv, rgb2ntsc} ## @end deftypefn ## FIXME: This function has a very different syntax than the Matlab ## one of the same name. ## Octave function does not support N, MAP, DITHER, or TOL arguments. ## Author: Tony Richardson <arichard@stark.cc.oh.us> ## Created: July 1994 ## Adapted-By: jwe function [x, map] = rgb2ind (R, G, B) if (nargin != 1 && nargin != 3) print_usage (); endif if (nargin == 1) rgb = R; if (ndims (rgb) != 3 || size (rgb, 3) != 3) error ("rgb2ind: argument is not an RGB image"); else R = rgb(:,:,1); G = rgb(:,:,2); B = rgb(:,:,3); endif elseif (! size_equal (R, G, B)) error ("rgb2ind: R, G, and B must have the same size"); endif x = reshape (1:numel (R), size (R)); map = unique ([R(:) G(:) B(:)], "rows"); [~, x] = ismember ([R(:) G(:) B(:)], map, "rows"); x = reshape (x, size (R)); ## a colormap is of class double and values between 0 and 1 switch (class (R)) case {"single", "double", "logical"} ## do nothing, return the same case {"uint8", "uint16"} map = double (map) / double (intmax (class (R))); case "int16" map = (double (im) + 32768) / 65535; otherwise error ("unsupported image class %s", im_class); endswitch ## we convert to the smallest class necessary to encode the image. Matlab ## documentation does not mention what it does when uint16 is not enough... ## When an indexed image is of integer class, there's a -1 offset to the ## colormap, hence the adjustment if (rows (map) < 256) x = uint8 (x - 1); elseif (rows (map) < 65536) x = uint16 (x - 1); else ## leave it as double endif endfunction %% FIXME: Need some functional tests or %!demo blocks %% Test input validation %!error rgb2ind () %!error rgb2ind (1,2,3,4,5,6,7)