Mercurial > octave
view scripts/image/rgb2ind.m @ 27980:bdad8ca48700
maint: Remove "Created:" lines from code base.
* lin2mu.m, mu2lin.m, bincoeff.m, common_size.m, deal.m, nextpow2.m,
postpad.m, prepad.m, repmat.m, shift.m, xor.m, inpolygon.m, rotx.m, roty.m,
rotz.m, getappdata.m, isappdata.m, rmappdata.m, setappdata.m, colormap.m,
gray.m, gray2ind.m, image.m, imagesc.m, ind2gray.m, ind2rgb.m, ocean.m,
rgb2ind.m, javachk.m, javamem.m, commutation_matrix.m, cross.m,
duplication_matrix.m, gls.m, housh.m, isdefinite.m, ishermitian.m,
issymmetric.m, null.m, ols.m, orth.m, qzhess.m, vech.m, __w2mpth__.m,
expand_rel_paths.m, make_rel_paths.m, daspect.m, pbaspect.m, rticks.m,
thetaticks.m, xticklabels.m, xticks.m, yticklabels.m, yticks.m, zticklabels.m,
zticks.m, comet.m, errorbar.m, loglogerr.m, __errplot__.m, semilogxerr.m,
semilogyerr.m, cla.m, copyobj.m, hdl2struct.m, linkaxes.m, __ghostscript__.m,
__gnuplot_get_var__.m, __gnuplot_has_feature__.m, __gnuplot_has_terminal__.m,
__gnuplot_open_stream__.m, struct2hdl.m, compan.m, conv.m, deconv.m, mpoles.m,
poly.m, polyder.m, polyfit.m, polyint.m, polyout.m, polyreduce.m, polyval.m,
polyvalm.m, residue.m, roots.m, __parse_movargs__.m, detrend.m, fftconv.m,
fftfilt.m, fftshift.m, ifftshift.m, movfun.m, movslice.m, beta.m, betaln.m,
lcm.m, pow2.m, corr.m, kurtosis.m, skewness.m, untabify.m, calendar.m,
datestr.m, datevec.m, eomday.m, now.m, weekday.m:
Remove "Created:" lines from code base.
author | Rik <rik@octave.org> |
---|---|
date | Tue, 21 Jan 2020 13:06:02 -0800 |
parents | bd51beb6205e |
children | 7f1cec12c240 |
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######################################################################## ## ## Copyright (C) 1994-2020 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{x}, @var{map}] =} rgb2ind (@var{rgb}) ## @deftypefnx {} {[@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. ## ## The input image @var{rgb} can be specified as a single matrix of size ## @nospell{MxNx3}, or as three separate variables, @var{R}, @var{G}, and ## @var{B}, its three color channels, red, green, and blue. ## ## It outputs an indexed image @var{x} and a colormap @var{map} to interpret ## an image exactly the same as the input. No dithering or other form of color ## quantization is performed. The output class of the indexed image @var{x} ## can be uint8, uint16 or double, whichever is required to specify the ## number of unique colors in the image (which will be equal to the number ## of rows in @var{map}) in order. ## ## Multi-dimensional indexed images (of size @nospell{MxNx3xK}) are also ## supported, both via a single input (@var{rgb}) or its three color channels ## as separate variables. ## ## @seealso{ind2rgb, rgb2hsv, rgb2gray} ## @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> ## 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) > 4 || 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 (R)); case "int16" map = (double (im) + 32768) / 65535; otherwise error ("rgb2ind: 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 ## Test input validation %!error rgb2ind () %!error rgb2ind (1,2,3,4,5,6,7) %!error <RGB> rgb2ind (rand (10, 10, 4)) ## FIXME: the following tests simply make sure that rgb2ind and ind2rgb ## reverse each other. We should have better tests for this. ## Typical usage %!test %! rgb = rand (10, 10, 3); %! [ind, map] = rgb2ind (rgb); %! assert (ind2rgb (ind, map), rgb); %! %! ## test specifying the RGB channels separated %! [ind, map] = rgb2ind (rgb(:,:,1), rgb(:,:,2), rgb(:,:,3)); %! assert (ind2rgb (ind, map), rgb); ## Test N-dimensional images %!test %! rgb = rand (10, 10, 3, 10); %! [ind, map] = rgb2ind (rgb); %! assert (ind2rgb (ind, map), rgb); %! [ind, map] = rgb2ind (rgb(:,:,1,:), rgb(:,:,2,:), rgb(:,:,3,:)); %! assert (ind2rgb (ind, map), rgb); ## Test output class %!test %! ## this should have more than 65536 unique colors %! rgb = rand (1000, 1000, 3); %! [ind, map] = rgb2ind (rgb); %! assert (class (ind), "double"); %! assert (class (map), "double"); %! %! ## and this should have between 255 and 65536 unique colors %! rgb = rand (20, 20, 3); %! [ind, map] = rgb2ind (rgb); %! assert (class (ind), "uint16"); %! assert (class (map), "double"); %! %! ## and this certainly less than 256 unique colors %! rgb = rand (10, 10, 3); %! [ind, map] = rgb2ind (rgb); %! assert (class (ind), "uint8"); %! assert (class (map), "double");