%IM_ROTATE Fixed mapping for image rotation
%
% B = IM_ROTATE(A,ALF)
% B = A*IM_ROTATE([],ALF)
% B = A*IM_ROTATE(ALF)
%
% INPUT
% A Dataset with object images (possibly multi-band)
% ALF Rotation angle (in radians),
% default: rotation to main axis
%
% OUTPUT
% B Dataset with rotated object images
%
% DESCRIPTION
% The objects stored as images in the dataset or datafile A are rotated
% using the IMROTATE command.
%
% SEE ALSO (<a href="http://37steps.com/prtools">PRTools Guide</a>)
% DATASETS, DATAFILES, DIP_IMAGE
% Copyright: R.P.W. Duin, r.p.w.duin@37steps.com
% Faculty EWI, Delft University of Technology
% P.O. Box 5031, 2600 GA Delft, The Netherlands
function b = im_rotate(varargin)
argin = shiftargin(varargin,'vector');
argin = setdefaults(argin,[],[]);
if mapping_task(argin,'definition')
b = define_mapping(argin,'fixed');
b = setname(b,'Image rotate');
else
[a,alf] = deal(argin{:});
if isa(a,'prdataset') % allows datafiles too
% error('Command cannot be used for datasets as it may change image size')
% elseif isdatafile(a)
isobjim(a);
b = filtim(a,mfilename,{alf});
b = setfeatsize(b,getfeatsize(a));
elseif isa(a,'double') || isa(a,'dip_image') % here we have a single image
a = double(a);
if isempty(alf)
m = im_moments(a,'central',[1 2 0; 1 0 2]');
C = [m(2) m(1); m(1) m(3)];
[E,D] = preig(C); [dummy,ind] = sort(diag(D));
alf = atan2(E(2,ind(1)),E(1,ind(1)))+pi/2;
end
b = imrotate(a,alf*360/(2*pi),'bilinear','crop');
end
end
return