laplace_image_prior

 LAPLACE_IMAGE_PRIOR calculate image prior
 Reg= laplace_image_prior( inv_model )
 Reg        => output regularization term
 inv_model  => inverse model struct

 This image prior is intended to be used as
  R'*R, but may be used as R for as well.

 The Laplace prior is a 2nd order high pass filter.
 On a rectangular mesh, it is a convolution with
   [-1,-1,-1;      [ 0;-1; 0
    -1, 8,-1    or  -1; 4;-1
    -1,-1,-1]        0;-1; 0]

 On a finite element mesh, we define the it as 
 -1 for each adjacent element, and 3 (in 2D) or 4 (in 3D)
 for the element itself

0001 function Reg= laplace_image_prior( inv_model );
0002 % LAPLACE_IMAGE_PRIOR calculate image prior
0003 % Reg= laplace_image_prior( inv_model )
0004 % Reg        => output regularization term
0005 % inv_model  => inverse model struct
0006 %
0007 % This image prior is intended to be used as
0008 %  R'*R, but may be used as R for as well.
0009 %
0010 % The Laplace prior is a 2nd order high pass filter.
0011 % On a rectangular mesh, it is a convolution with
0012 %   [-1,-1,-1;      [ 0;-1; 0
0013 %    -1, 8,-1    or  -1; 4;-1
0014 %    -1,-1,-1]        0;-1; 0]
0015 %
0016 % On a finite element mesh, we define the it as
0017 % -1 for each adjacent element, and 3 (in 2D) or 4 (in 3D)
0018 % for the element itself
0019 
0020 % (C) 2005 Andy Adler. License: GPL version 2 or version 3
0021 % $Id: laplace_image_prior.m 3125 2012-06-08 16:16:24Z bgrychtol $
0022 
0023 warning('EIDORS:deprecated','LAPLACE_IMAGE_PRIOR is deprecated as of 08-Jun-2012. Use PRIOR_LAPLACE instead.');
0024 Reg = prior_laplace(inv_model);