--- /dev/null
+## Copyright (C) 2002 Jeff Orchard <jorchard@cs.uwaterloo.ca>
+##
+## 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 (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 program; If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} imrotate(@var{M}, @var{theta}, @var{method}, @var{bbox})
+## Rotation of a 2D matrix.
+##
+## Applies a rotation of @var{THETA} degrees to matrix @var{M}.
+##
+## The @var{method} argument is not implemented, and is only included for compatibility with Matlab.
+## This function uses Fourier interpolation,
+## decomposing the rotation matrix into 3 shears.
+##
+## @var{bbox} can be either 'loose' or 'crop'.
+## 'loose' allows the image to grow to accomodate the rotated image.
+## 'crop' keeps the same size as the original, clipping any part of the image
+## that is moved outside the bounding box.
+## @end deftypefn
+
+## Author: Jeff Orchard <jorchard@cs.uwaterloo.ca>
+## Created: Oct. 14, 2002
+
+function fs = imrotate_Fourier(f, theta, method="fourier", bbox="loose")
+
+ ## Input checking
+ if (nargin < 2)
+ error("imrotate_Fourier: not enough input arguments");
+ endif
+ [imrows, imcols, tmp] = size(f);
+ if (tmp != 1)
+ error("imrotate_Fourier: first input argument must be a gray-scale image");
+ endif
+ if (!isscalar(theta))
+ error("imrotate_Fourier: second input argument must be a real scalar");
+ endif
+
+ # Get original dimensions.
+ [ydim_orig, xdim_orig] = size(f);
+
+ # This finds the index coords of the centre of the image (indices are base-1)
+ # eg. if xdim_orig=8, then xcentre_orig=4.5 (half-way between 1 and 8)
+ xcentre_orig = (xdim_orig+1) / 2;
+ ycentre_orig = (ydim_orig+1) / 2;
+
+ # Pre-process the angle ===========================================================
+ # Whichever 90 degree multiple theta is closest to, that multiple of 90 will
+ # be implemented by rot90. The remainder will be done by shears.
+
+ # This ensures that 0 <= theta < 360.
+ theta = rem( rem(theta,360) + 360, 360 );
+
+ # This is a flag to keep track of 90-degree rotations.
+ perp = 0;
+
+ if ( theta>=0 && theta<=45 )
+ phi = theta;
+ elseif ( theta>45 && theta<=135 )
+ phi = theta - 90;
+ f = rot90(f,1);
+ perp = 1;
+ elseif ( theta>135 && theta<=225 )
+ phi = theta - 180;
+ f = rot90(f,2);
+ elseif ( theta>225 && theta<=315 )
+ phi = theta - 270;
+ f = rot90(f,3);
+ perp = 1;
+ else
+ phi = theta;
+ endif
+
+
+
+ if ( phi == 0 )
+ fs = f;
+ if ( strcmp(bbox,"loose") == 1 )
+ return;
+ else
+ xmax = xcentre_orig;
+ ymax = ycentre_orig;
+ if ( perp == 1 )
+ xmax = max([xmax ycentre_orig]);
+ ymax = max([ymax xcentre_orig]);
+ [ydim xdim] = size(fs);
+ xpad = ceil( xmax - (xdim+1)/2 );
+ ypad = ceil( ymax - (ydim+1)/2 );
+ fs = impad(fs, [xpad,xpad], [ypad,ypad], "zeros");
+ endif
+ xcentre_new = (size(fs,2)+1) / 2;
+ ycentre_new = (size(fs,1)+1) / 2;
+ endif
+ else
+
+ # At this point, we can assume -45<theta<45 (degrees)
+
+ phi = phi * pi / 180;
+ theta = theta * pi / 180;
+ R = [ cos(theta) -sin(theta) ; sin(theta) cos(theta) ];
+
+ # Find max of each dimension... this will be expanded for "loose" and "crop"
+ xmax = xcentre_orig;
+ ymax = ycentre_orig;
+
+ # If we don't want wrapping, we have to zeropad.
+ # Cropping will be done later, if necessary.
+ if ( strcmp(bbox, "wrap") == 0 )
+ corners = ( [ xdim_orig xdim_orig -xdim_orig -xdim_orig ; ydim_orig -ydim_orig ydim_orig -ydim_orig ] + 1 )/ 2;
+ rot_corners = R * corners;
+ xmax = max([xmax rot_corners(1,:)]);
+ ymax = max([ymax rot_corners(2,:)]);
+
+ # If we are doing a 90-degree rotation first, we need to make sure our
+ # image is large enough to hold the rot90 image as well.
+ if ( perp == 1 )
+ xmax = max([xmax ycentre_orig]);
+ ymax = max([ymax xcentre_orig]);
+ endif
+
+ [ydim xdim] = size(f);
+ xpad = ceil( xmax - xdim/2 );
+ ypad = ceil( ymax - ydim/2 );
+ %f = impad(f, [xpad,xpad], [ypad,ypad], "zeros");
+ xcentre_new = (size(f,2)+1) / 2;
+ ycentre_new = (size(f,1)+1) / 2;
+ endif
+
+ #size(f)
+ [S1, S2] = MakeShears(phi);
+
+ tic;
+ f1 = imshear(f, 'x', S1(1,2), 'loose');
+ f2 = imshear(f1, 'y', S2(2,1), 'loose');
+ fs = real( imshear(f2, 'x', S1(1,2), 'loose') );
+ %fs = f2;
+ xcentre_new = (size(fs,2)+1) / 2;
+ ycentre_new = (size(fs,1)+1) / 2;
+ endif
+
+ if ( strcmp(bbox, "crop") == 1 )
+
+ # Crop to original dimensions
+ x1 = ceil (xcentre_new - xdim_orig/2);
+ y1 = ceil (ycentre_new - ydim_orig/2);
+ fs = fs (y1:(y1+ydim_orig-1), x1:(x1+xdim_orig-1));
+
+ elseif ( strcmp(bbox, "loose") == 1 )
+
+ # Find tight bounds on size of rotated image
+ # These should all be positive, or 0.
+ xmax_loose = ceil( xcentre_new + max(rot_corners(1,:)) );
+ xmin_loose = floor( xcentre_new - max(rot_corners(1,:)) );
+ ymax_loose = ceil( ycentre_new + max(rot_corners(2,:)) );
+ ymin_loose = floor( ycentre_new - max(rot_corners(2,:)) );
+
+ %fs = fs( (ymin_loose+1):(ymax_loose-1) , (xmin_loose+1):(xmax_loose-1) );
+ fs = fs( (ymin_loose+1):(ymax_loose-1) , (xmin_loose+1):(xmax_loose-1) );
+
+ endif
+
+ ## Prevent overshooting
+ if (strcmp(class(f), "double"))
+ fs(fs>1) = 1;
+ fs(fs<0) = 0;
+ endif
+
+endfunction
+
+function [S1, S2] = MakeShears(theta)
+ S1 = eye(2);
+ S2 = eye(2);
+
+ S1(1,2) = -tan(theta/2);
+ S2(2,1) = sin(theta);
+endfunction
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff