anisotropic function convert to C code using matlab coder

Hi everyone,

is there anyone know how to change this function to be applicable to convert in C code using Matlab coder ??

function diff_sig = anisodiff1D(sig, num_iter, delta_t, kappa, option)%#codegen

%       ARGUMENT DESCRIPTION:
%               SIG      - input column vector (Nx1).
%               NUM_ITER - number of iterations. 
%               DELTA_T  - integration constant (0 <= delta_t <= 1/3).
%                          Usually, due to numerical stability this 
%                          parameter is set to its maximum value.
%               KAPPA    - gradient modulus threshold that controls the conduction.
%               OPTION   - conduction coefficient functions proposed by Perona & Malik:
%                          1 - c(x,t) = exp(-(nablaI/kappa).^2),
%                              privileges high-contrast edges over low-contrast ones. 
%                          2 - c(x,t) = 1./(1 + (nablaI/kappa).^2),
%                              privileges wide regions over smaller ones. 
% 
%       OUTPUT DESCRIPTION:
%               DIFF_SIG - (diffused) signal with the largest scale-space parameter.
% 
%   Example
%   -------------
%   s = exp(-(-10:0.1:10).^2/2.5)' + rand(length(-10:0.1:10),1);
%   num_iter = 15;
%   delta_t = 1/3;
%   kappa = 30;
%   option = 2;
%   ad = anisodiff1D(s,num_iter,delta_t,kappa,option);
%   figure, subplot 121, plot(s), axis([0 200 0 2]), subplot 122, plot(ad), axis([0 200 0 2])
% 
% See also anisodiff2D, anisodiff3D.

% References: 
%   P. Perona and J. Malik. 
%   Scale-Space and Edge Detection Using Anisotropic Diffusion.
%   IEEE Transactions on Pattern Analysis and Machine Intelligence, 
%   12(7):629-639, July 1990.
% 
%   G. Grieg, O. Kubler, R. Kikinis, and F. A. Jolesz.
%   Nonlinear Anisotropic Filtering of MRI Data.
%   IEEE Transactions on Medical Imaging,
%   11(2):221-232, June 1992.
% 
%   MATLAB implementation based on Peter Kovesi's anisodiff(.):
%   P. D. Kovesi. MATLAB and Octave Functions for Computer Vision and Image Processing.
%   School of Computer Science & Software Engineering,
%   The University of Western Australia. Available from:
%   <http://www.csse.uwa.edu.au/~pk/research/matlabfns/>.
% 
% Credits:
% Daniel Simoes Lopes
% ICIST
% Instituto Superior Tecnico - Universidade Tecnica de Lisboa
% danlopes (at) civil ist utl pt
% http://www.civil.ist.utl.pt/~danlopes
%
% May 2007 original version.

% Convert input signal to double

sig = double(sig);

% PDE (partial differential equation) initial condition

diff_sig = sig;

% Center point distance

dx = 1;

% 1D convolution masks - finite differences

hW = [1 -1 0]';
hE = [0 -1 1]';

% Anisotropic diffusion

for t = 1:num_iter

% Finite differences

          nablaW = imfilter(diff_sig,hW,'conv');
          nablaE = imfilter(diff_sig,hE,'conv');   

% Diffusion function

          if option == 1
              cW = exp(-(nablaW/kappa).^2);
              cE = exp(-(nablaE/kappa).^2);
          elseif option == 2
              cW = 1./(1+(nablaW/kappa).^2);
              cE = 1./(1+(nablaE/kappa).^2);
          end

% Discrete PDE solution

          diff_sig = diff_sig + ... 
                     delta_t*(...
                     (1/(dx^2))*cW.*nablaW + (1/(dx^2))*cE.*nablaE);

% Iteration warning
       fprintf('\rIteration %d\n',t);
end

Answer 1

[Walter Roberson]

imfilter() is not supported for Coder code generation; see http://www.mathworks.com/help/toolbox/eml/ug/bq1h2z7-11.html

Perhaps you could rewrite it in terms of conv() ?