Revision: 9269
http://octave.svn.sourceforge.net/octave/?rev=9269&view=rev
Author: carandraug
Date: 2011-12-05 04:20:50 +0000 (Mon, 05 Dec 2011)
Log Message:
-----------
isrgb:
* pretty much complete rewrite based on isgray
* added Kai Habel to copyright since it's based on isgray from him
* improved help text
* update license to GPLv3+
* checked matlab, logical MxNx3 matrix should return false
Modified Paths:
--------------
trunk/octave-forge/main/image/inst/isrgb.m
Modified: trunk/octave-forge/main/image/inst/isrgb.m
===================================================================
--- trunk/octave-forge/main/image/inst/isrgb.m 2011-12-05 04:06:15 UTC (rev 9268)
+++ trunk/octave-forge/main/image/inst/isrgb.m 2011-12-05 04:20:50 UTC (rev 9269)
@@ -1,8 +1,10 @@
-## Copyright (C) 2004 Josep Mones i Teixidor
+## Copyright (C) 2000 Kai Habel <kai...@gm...>
+## Copyright (C) 2004 Josep Mones i Teixidor <jm...@pu...>
+## Copyright (C) 2011 Carnë Draug <car...@gm...>
##
## This program 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 2 of the License, or
+## the Free Software Foundation; either version 3 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
@@ -14,67 +16,64 @@
## along with this program; If not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
-## @deftypefn {Function File} {@var{flag} = } isrgb (@var{A})
-## Returns true if parameter is a RGB image.
+## @deftypefn {Function File} {@var{bool} = } isrgb (@var{img})
+## Return true if @var{img} is a RGB image.
##
-## @code{flag=isrgb(A)} returns 1 if @var{A} is a RGB image and 0 if
-## not.
-##
-## To the decide @code{isrgb} uses the follow algorithm:
+## A variable is considereed to be a RGB image if it is 3-dimensional,
+## non-sparse matrix, of size MxNx3 and:
## @itemize @bullet
-## @item
-## If @var{A} is of class double then it checks if all values are
-## between 0 and 1, and if size is m-by-n-by-3.
-## @item
-## If @var{A} is of class uint16, uint8 or logical then it checks is m-by-n-by-3.
+## @item is of class double and all values are in the range [0, 1];
+## @item is of class uint8 or uint16.
## @end itemize
##
-## @strong{Compatibility notes:}
+## Note that RGB time-series image have 4 dimensions (NxMx3xtime) but
+## isrgb will still return false.
##
-## Information needed on whether MATLAB accepts logical arrays as RGB
-## images (now this functions accepts them if they are m-by-n-by-3 arrays.
-##
+## @seealso{isbw, isgray, isind}
## @end deftypefn
-## TODO: Check if logical arrays should be considered RGB
+function bool = isrgb (img)
-## Author: Josep Mones i Teixidor <jm...@pu...>
+ if (nargin != 1)
+ print_usage;
+ endif
-function flag = isrgb(A)
- if (nargin!=1)
- usage("flag=isrgb(A)");
+ bool = false;
+ if (ismatrix (img) && ndims (img) == 3 && size (img, 3) == 3 && !issparse (img))
+ switch (class (img))
+ case "double"
+ ## to speed this up, we can look at a sample of the image first
+ bool = is_rgb_double (img(1:ceil (rows (img) /100), 1:ceil (columns (img) /100)));
+ if (bool)
+ ## sample was true, we better make sure it's real
+ bool = is_rgb_double (img);
+ endif
+ case {"uint8", "uint16"}
+ bool = true;
+ endswitch
endif
-
- if(ismatrix(A))
- flag=1;
- s=size(A);
- if(length(s)!=3 || s(3)!=3)
- flag=0; ## false if not m-by-n-by-3
- elseif(strcmp(typeinfo(A),"matrix") && (any(A(:)<0) || any(A(:)>1)))
- flag=0; ## false if class double but items are <0 or >1
- endif
- else
- flag=0;
- endif
+
endfunction
+function bool = is_rgb_double (img)
+ bool = all ((img(:) >= 0 & img(:) <= 1) | isnan (img(:)));
+endfunction
%!demo
%! isrgb(rand(1,2,3))
%! # A 1-by-2-by-3 double matrix with elements between 0 and 1 is a RGB image.
-
%!# Non-matrix
-%!assert(isrgb("this is not a RGB image"),0);
+%!assert(isrgb("this is not a RGB image"),false);
%!# Double matrix tests
-%!assert(isrgb(rand(5,5)),0);
-%!assert(isrgb(rand(5,5,1,5)),0);
-%!assert(isrgb(rand(5,5,3,5)),0);
-%!assert(isrgb(rand(5,5,3)),1);
-%!assert(isrgb(ones(5,5,3)),1);
-%!assert(isrgb(ones(5,5,3)+.0001),0);
-%!assert(isrgb(zeros(5,5,3)-.0001),0);
+%!assert(isrgb(rand(5,5)),false);
+%!assert(isrgb(rand(5,5,1,5)),false);
+%!assert(isrgb(rand(5,5,3,5)),false);
+%!assert(isrgb(rand(5,5,3)),true);
+%!assert(isrgb(ones(5,5,3)),true);
+%!assert(isrgb(ones(5,5,3)+.0001),false);
+%!assert(isrgb(zeros(5,5,3)-.0001),false);
-%!# Logical
-%!assert(isrgb(logical(round(rand(5,5,3)))),1);
+%!# Logical -- checked in matlab, should return false
+%!assert(isrgb(logical(round(rand(5,5,3)))),false);
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