Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / label2rgb.m

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+## Copyright (C) 2006  Søren Hauberg
+## 
+## 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, or (at your option)
+## any later version.
+## 
+## This program 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 this file.  If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{RGB} = label2rgb(@var{L})
+## @deftypefnx{Function File} @var{RGB} = label2rgb(@var{L}, @var{map})
+## @deftypefnx{Function File} @var{RGB} = label2rgb(@var{L}, @var{map}, @var{background})
+## @deftypefnx{Function File} @var{RGB} = label2rgb(@var{L}, @var{map}, @var{background}, @var{order})
+## Converts a labeled image to an RGB image.
+##
+## label2rgb(@var{L}) returns a color image, where the background color
+## (the background is the zero-labeled pixels) is white, and all other
+## colors come from the @code{jet} colormap.
+##
+## label2rgb(@var{L}, @var{map}) uses colors from the given colormap.
+## @var{map} can be
+## @itemize
+## @item A string containing the name of a function to be called to
+## produce a colormap. The default value is "jet".
+## @item A handle to a function to be called to produce a colormap.
+## @item A @var{N}-by-3 colormap matrix.
+## @end itemize
+##
+## label2rgb(@var{L}, @var{map}, @var{background}) sets the background
+## color. @var{background} can be a 3-vector corresponding to the wanted
+## RGB color, or one of the following strings
+## @table @samp
+## @item "b"
+## The background color will be blue.
+## @item "c"
+## The background color will be cyan.
+## @item "g"
+## The background color will be green.
+## @item "k"
+## The background color will be black.
+## @item "m"
+## The background color will be magenta.
+## @item "r"
+## The background color will be red.
+## @item "w"
+## The background color will be white. This is the default behavior.
+## @item "y"
+## The background color will be yellow.
+## @end table
+##
+## label2rgb(@var{L}, @var{map}, @var{background}, @var{order}) allows for random
+## permutations of the colormap. @var{order} must be one of the following strings
+## @table @samp
+## @item "noshuffle"
+## The colormap is not permuted in any ways. This is the default.
+## @item "shuffle"
+## The used colormap is permuted randomly.
+## @end table
+## @seealso{bwlabel, ind2rgb}
+## @end deftypefn
+
+function rgb = label2rgb(L, map = "jet", background = "w", order = "noshuffle")
+  ## Input checking
+  if (nargin < 1)
+    print_usage();
+  endif
+  if ( !ismatrix(L) || ndims(L) != 2 || any(L(:) != round(L(:))) || any(L(:) < 0) )
+    error("label2rgb: first input argument must be a labelled image");
+  endif
+  if ( !ischar(map) && !isa(map, "function_handle") && !(ismatrix(map) && ndims(map)==2 && columns(map)==3) )
+    error("label2rgb: second input argument must be a color map or a function that can generate a colormap");
+  endif
+  if ( !ischar(background) && !(isreal(background) && numel(background)==3) )
+    error("label2rgb: third input argument must be a color given as a string or a 3-vector");
+  endif
+  if ( !any(strcmpi(order, {"noshuffle", "shuffle"})) )
+    error("label2rgb: fourth input argument must be either 'noshuffle' or 'shuffle'");
+  endif
+  
+  ## Convert map to a matrix if needed
+  num_objects = max(L(:));
+  if (ischar(map) || isa(map, "function_handle"))
+    map = feval(map, num_objects+1);
+  endif
+
+  num_colors  = rows(map);
+  if (num_objects > num_colors)
+    warning("label2rgb: number of objects exceeds number of colors in the colormap");
+  endif
+
+  ## Handle the background color
+  if (ischar(background))
+    switch (background(1))
+      case 'b' background = [0, 0, 1];
+      case 'c' background = [0, 1, 1];
+      case 'g' background = [0, 1, 0];
+      case 'k' background = [0, 0, 0];
+      case 'm' background = [1, 0, 1];
+      case 'r' background = [1, 0, 0];
+      case 'w' background = [1, 1, 1];
+      case 'y' background = [1, 1, 0];
+      otherwise
+        error("label2rgb: unknown background color '%s'", background);
+    endswitch
+  endif
+  background = background(:)';
+  if (min(background) < 0 || max(background) > 1)
+    error("label2rgb: the background color must be in the interval [0, 1]");
+  endif
+  
+  ## Should we shuffle the colormap?
+  if (strcmpi(order, "shuffle"))
+    r = rows(map);
+    map = map(randperm(r),:);
+  endif
+  
+  ## If the background color is in the color map: remove it
+  idx = find((map(:,1) == background(1)) & (map(:,2) == background(2)) & (map(:,3) == background(3)));
+  if (!isempty(idx))
+    map(idx, :) = [];
+  endif
+  
+  ## Insert the background color as the first element in the color map
+  map = [background; map];
+  
+  ## Convert L to an RGB image
+  rgb = ind2rgb(L+1, map);
+  rgb /= max(rgb(:));
+  rgb = uint8(255*rgb);
+endfunction