Mercurial > forge
changeset 11504:110b520dae68 octave-forge
strel: implement line and periodic line. Submitted by Roberto Metere <roberto@metere.it>
| author | carandraug |
|---|---|
| date | Sat, 02 Mar 2013 15:03:38 +0000 |
| parents | 314a9c3bfaba |
| children | c2560f01b244 |
| files | main/image/inst/@strel/strel.m |
| diffstat | 1 files changed, 114 insertions(+), 4 deletions(-) [+] |
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--- a/main/image/inst/@strel/strel.m Sat Mar 02 14:38:24 2013 +0000 +++ b/main/image/inst/@strel/strel.m Sat Mar 02 15:03:38 2013 +0000 @@ -1,4 +1,4 @@ -## Copyright (C) 2012 Roberto Metere <roberto@metere.it> +## Copyright (C) 2012,2013 Roberto Metere <roberto@metere.it> ## Copyright (C) 2012 Carnë Draug <carandraug@octave.org> ## ## This program is free software; you can redistribute it and/or modify it under @@ -59,6 +59,10 @@ ## Create disk shaped flat structuring element. @var{radius} must be a positive ## integer. ## +## @deftypefnx {Function File} {} strel ("line", @var{len}, @var{deg}) +## Create line shaped flat structuring element. @var{len} must be a positive +## real number. @var{deg} must be a real number. +## ## @deftypefnx {Function File} {} strel ("octagon", @var{apothem}) ## Create octagon shaped flat structuring element. @var{apothem} must be a ## positive integer that specifies the distance from the origin to the sides of @@ -69,6 +73,13 @@ ## at the origin while the other is placed with @var{offset} in relation to the ## origin. @var{offset} must then be a 2 element vector for the coordinates. ## +## @deftypefnx {Function File} {} strel ("periodicline", @var{p}, @var{v}) +## Create periodic line shaped flat structuring element. A periodic line will +## be built with 2*@var{p}+1 points around the origin included. These points will +## be displaced in accordance with the offset @var{v} at distances: 1*@var{v}, +## -1*@var{v}, 2*@var{v}, -2*@var{v}, ..., @var{p}*@var{v}, -@var{p}*@var{v}. +## Therefore @var{v} must be a 2 element vector for the coordinates. +## ## @deftypefnx {Function File} {} strel ("rectangle", @var{dimensions}) ## Creates a rectangular shaped flat structuring element. @var{dimensions} must ## be a two element vector of positive integers with the number of rows and @@ -191,8 +202,68 @@ SE.nhood = fspecial ("disk", radius) > 0; SE.flat = true; -# case "line" - ## TODO implement line shape + + case "line" + if (numel (varargin) == 2) + linelen = varargin{1}; + degrees = varargin{2}; + else + error ("strel: a line shape needs 2 arguments"); + endif + if (! (isscalar (linelen) && isnumeric (linelen) && linelen > 0)) + error ("strel: LEN must be a positive real number"); + elseif (! (isscalar (degrees) && isnumeric (degrees))) + error ("strel: DEG must be a real number"); + endif + + ## Line length are always odd, to center strel at the middle of the line. + ## We look it as a diameter of a circle with given slope + # It computes only lines with angles between 0 and 44.9999 + deg90 = mod (degrees, 90); + if (deg90 > 45) + alpha = pi * (90 - deg90) / 180; + else + alpha = pi * deg90 / 180; + endif + ray = (linelen - 1)/2; + + ## We are interested only in the discrete rectangle which contains the diameter + ## However we focus our attention to the bottom left quarter of the circle, + ## because of the central symmetry. + c = round (ray * cos (alpha)) + 1; + r = round (ray * sin (alpha)) + 1; + + ## Line rasterization + line = false (r, c); + m = tan (alpha); + x = [1:c]; + y = r - fix (m .* (x - 0.5)); + indexes = sub2ind ([r c], y, x); + line(indexes) = true; + + ## We view the result as 9 blocks. + # Preparing blocks + linestrip = line(1, 1:c - 1); + linerest = line(2:r, 1:c - 1); + z = false (r - 1, c); + + # Assemblying blocks + SE.nhood = vertcat ( + horzcat (z, linerest(end:-1:1,end:-1:1)), + horzcat (linestrip, true, linestrip(end:-1:1,end:-1:1)), + horzcat (linerest, z(end:-1:1,end:-1:1)) + ); + + # Rotate/transpose/flip? + sect = fix (mod (degrees, 180) / 45); + switch (sect) + case 1, SE.nhood = transpose (SE.nhood); + case 2, SE.nhood = rot90 (SE.nhood, 1); + case 3, SE.nhood = fliplr (SE.nhood); + otherwise, # do nothing + endswitch + + SE.flat = true; case "octagon" if (numel (varargin) == 1) @@ -237,7 +308,27 @@ SE.flat = true; case "periodicline" - ## TODO implement periodicline shape + if (numel (varargin) == 2) + p = varargin{1}; + v = varargin{2}; + else + error ("strel: a periodic line shape needs 2 arguments"); + endif + if (! is_positive_integer (p)) + error ("strel: P must be a positive integer"); + elseif (! ismatrix (v) || numel (v) != 2 || ! isnumeric (v)) + error ("strel: V must be a 2 element vector"); + elseif (any (fix (v) != v)) + error ("strel: values of V must be integers"); + endif + + lengths = abs (2*p*v) + 1; + SE.nhood = false (lengths); + origin = (lengths + 1)/2; + for i = -p:p + point = i*v + origin; + SE.nhood(point(1), point(2)) = true; + endfor case "rectangle" if (numel (varargin) == 1) @@ -307,6 +398,24 @@ %! 0 1 1 1 1 1 0 %! 0 0 0 1 0 0 0]; %!assert (getnhood (strel ("disk", 3)), logical (shape)); +%! shape = [1 1 1]; +%!assert (getnhood (strel ("line", 3.9, 20.17)), logical (shape)); +%! shape = [0 0 1 +%! 0 1 0 +%! 1 0 0]; +%!assert (getnhood (strel ("line", 3.9, 20.18)), logical (shape)); +%! shape = [1 0 0 0 0 0 0 0 0 +%! 0 1 0 0 0 0 0 0 0 +%! 0 0 1 0 0 0 0 0 0 +%! 0 0 1 0 0 0 0 0 0 +%! 0 0 0 1 0 0 0 0 0 +%! 0 0 0 0 1 0 0 0 0 +%! 0 0 0 0 0 1 0 0 0 +%! 0 0 0 0 0 0 1 0 0 +%! 0 0 0 0 0 0 1 0 0 +%! 0 0 0 0 0 0 0 1 0 +%! 0 0 0 0 0 0 0 0 1]; +%!assert (getnhood (strel ("line", 14, 130)), logical (shape)); %! shape = [0 0 1 1 1 0 0 %! 0 1 1 1 1 1 0 %! 1 1 1 1 1 1 1 @@ -359,6 +468,7 @@ %!error strel("arbitrary", [0 0 1], "stuff") %!error strel("diamond", -3) %!error strel("disk", -3) +%!error strel("line", 0, 45) %!error strel("octagon", 4) %!error strel("pair", [45 67 90]) %!error strel("rectangle", 2)