spm_right_to_neuro_vox

 Change Neuromag-Head coordinate to Right-hand SPM [m] coordinate
  Point coordinate 
  [Vhead,Vox] = spm_right_to_neuro_vox(Vspm,trans_info,Vdim,Vsize)
  Normal vector
  [Vhead,Vox] = spm_right_to_neuro_vox(Vspm,trans_info,Vdim,Vsize,1)
 ---- Input
 Vspm : NV x 3 right-handed SPM coordinate 
 Vdim  : Voxel dimension of Analize image
 Vsize : Voxel size of Analize image
 nflag = 0 : coordinate transformation (default)
       = 1 : normal vector transformation
           : no translation is applied
 ---- Output
 Vhead : NV x 3 Neuromag-Head coordinate
 Vox   : NV x 3 left-handed Voxcel coordinate 

 --- MRI-Voxel coordinate  (Image based)

 [Left-hand coordinate]
 X:Right(1) -> Left(256)   R->L
 Y:Front(1) -> Back(256)   A->P
 Z:Top(1)   -> Bottom(136) S->I

 --- SPM coordinate (Image based)

 [Right-hand coordinate]
 X: Left(-191/2)   -> Right(191/2) 
 Y: Back(-256/2)   -> Front(256/2)
 Z: Bottom(-256/2) -> Top(256/2) 

 --- Head coordinate
 X : from left to right : LPA -> RPA
 Y : from back to front : Nasion -> x-axis
 Z : from bottom to up.

 Masa-aki Sato 2009-4-13

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function    [Vhead,Vox] = spm_right_to_neuro_vox(Vspm,trans_info,Vdim,Vsize,nflag)
0002 % Change Neuromag-Head coordinate to Right-hand SPM [m] coordinate
0003 %  Point coordinate
0004 %  [Vhead,Vox] = spm_right_to_neuro_vox(Vspm,trans_info,Vdim,Vsize)
0005 %  Normal vector
0006 %  [Vhead,Vox] = spm_right_to_neuro_vox(Vspm,trans_info,Vdim,Vsize,1)
0007 % ---- Input
0008 % Vspm : NV x 3 right-handed SPM coordinate
0009 % Vdim  : Voxel dimension of Analize image
0010 % Vsize : Voxel size of Analize image
0011 % nflag = 0 : coordinate transformation (default)
0012 %       = 1 : normal vector transformation
0013 %           : no translation is applied
0014 % ---- Output
0015 % Vhead : NV x 3 Neuromag-Head coordinate
0016 % Vox   : NV x 3 left-handed Voxcel coordinate
0017 %
0018 % --- MRI-Voxel coordinate  (Image based)
0019 %
0020 % [Left-hand coordinate]
0021 % X:Right(1) -> Left(256)   R->L
0022 % Y:Front(1) -> Back(256)   A->P
0023 % Z:Top(1)   -> Bottom(136) S->I
0024 %
0025 % --- SPM coordinate (Image based)
0026 %
0027 % [Right-hand coordinate]
0028 % X: Left(-191/2)   -> Right(191/2)
0029 % Y: Back(-256/2)   -> Front(256/2)
0030 % Z: Bottom(-256/2) -> Top(256/2)
0031 %
0032 % --- Head coordinate
0033 % X : from left to right : LPA -> RPA
0034 % Y : from back to front : Nasion -> x-axis
0035 % Z : from bottom to up.
0036 %
0037 % Masa-aki Sato 2009-4-13
0038 %
0039 % Copyright (C) 2011, ATR All Rights Reserved.
0040 % License : New BSD License(see VBMEG_LICENSE.txt)
0041 
0042 if nargin < 4, error('Input argument error'); end
0043 if nargin < 5, nflag = 0; end;
0044 
0045 NV   = size(Vspm,1);
0046 Vox  = zeros(NV,3);
0047 % Change [m] to [mm]
0048 Vspm = Vspm*1000;
0049 
0050 if nflag == 1
0051     % SPM -> Voxcel
0052     Vox(:,1) = - Vspm(:,1)/Vsize(1);
0053     Vox(:,2) = - Vspm(:,2)/Vsize(2);
0054     Vox(:,3) = - Vspm(:,3)/Vsize(3);
0055     
0056     % Voxcel -> Head
0057     Vhead  = Vox * inv(trans_info.trans_head2vox(1:3,1:3));
0058     
0059     % normalization
0060     Vhead  = vb_repmultiply(Vhead , 1./sqrt(sum(Vhead.^2, 2)) );
0061     %Vox  = repmultiply(Vox , 1./sqrt(sum(Vox.^2, 2)) );
0062     % Vox coordinate is not physical coordinate and different scale axis
0063 else
0064     % SPM -> Voxcel
0065     Vox(:,1) =  - Vspm(:,1) /Vsize(1) + Vdim(1)*0.5;
0066     Vox(:,2) =  - Vspm(:,2) /Vsize(2) + Vdim(2)*0.5;
0067     Vox(:,3) =  - Vspm(:,3) /Vsize(3) + Vdim(3)*0.5;
0068     
0069     % Voxcel -> Head
0070     Vhead  = [Vox ones(NV,1)] * inv(trans_info.trans_head2vox);
0071 end
0072 
0073 Vhead = Vhead(:,1:3);