1## Copyright (C) 2000 Kai Habel <kai.habel@gmx.de>
2## Copyright (C) 2011, 2015 Carnë Draug <carandraug+dev@gmail.com>
3##
4## This program is free software; you can redistribute it and/or modify
5## it under the terms of the GNU General Public License as published by
6## the Free Software Foundation; either version 3 of the License, or
7## (at your option) any later version.
8##
9## This program is distributed in the hope that it will be useful,
10## but WITHOUT ANY WARRANTY; without even the implied warranty of
11## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12## GNU General Public License for more details.
13##
14## You should have received a copy of the GNU General Public License
15## along with this program; if not, see <http://www.gnu.org/licenses/>.
16
17## -*- texinfo -*-
18## @deftypefn {Function File} {} isind (@var{img})
19## Return true if @var{img} is an indexed image.
20##
21## A variable can be considered an indexed image if it is a non-sparse,
22## real array of size @nospell{MxNx1xK}, and:
23##
24## @itemize @bullet
25## @item of class double with all integers above zero;
26## @item of class uint8 or uint16.
27## @end itemize
28##
29## @emph{Note}: despite their suggestive names, the functions isbw,
30## isgray, isind, and isrgb, are ambiguous since it is not always possible
31## to distinguish between those image types.  For example: an uint8 matrix
32## can be both a grayscale and indexed image; a grayscale image may have
33## values outside the range [0 1].  They are good to dismiss input as an
34## invalid image type, but not for identification.
35##
36## @seealso{ind2gray, ind2rgb, isbw, isgray, isindex, isrgb}
37## @end deftypefn
38
39function bool = isind (img)
40
41  if (nargin != 1)
42    print_usage;
43  endif
44
45  bool = false;
46  if (isimage (img) && ndims (img) < 5 && size (img, 3) == 1)
47    if (isfloat (img))
48      bool = isindex (img);
49    elseif (any (isa (img, {"uint8", "uint16"})))
50      bool = true;
51    endif
52  endif
53
54endfunction
55
56%!assert (isind ([]), false);
57%!assert (isind (1:10), true);
58%!assert (isind (0:10), false);
59%!assert (isind (1), true);
60%!assert (isind (0), false);
61%!assert (isind ([1.3 2.4]), false);
62%!assert (isind ([1 2; 3 4]), true);
63%!assert (isind (randi (100, 10, 10, 1, 4)), true);
64%!assert (isind (randi (100, 10, 10, 3, 4)), false);
65%!assert (isind (randi (100, 10, 10, 1, 4, 2)), false);
66