apply_perturbation_to_points

 ==============================================================
 APPLY_PERTURBATION_TO_POINTS: Apply noise to (correct) warp


    GENERAL

      points= apply_perturbation_to_points (points, offset_extent)

    INPUT/S

      -points
         The points defining the CPS warp
      
      -offset entent
         Defines the amount of noise/distortion

      -perturbation_method
         The method of applying the change
           
    OUTPUT/S

      -points
         The points after offset application

    PENDING WORK

      -

    KNOWN BUG/S

      -

    COMMENT/S

      -

    RELATED FUNCTION/S

      

    ABOUT

      -Created:     March 10th, 2004
      -Last update: April 11st, 2004
      -Revision:    0.0.6
      -Author:      R. S. Schestowitz, University of Manchester
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0001 function points = apply_perturbation_to_points (points, offset_extent, perturbation_method)
0002 % ==============================================================
0003 % APPLY_PERTURBATION_TO_POINTS: Apply noise to (correct) warp
0004 %
0005 %
0006 %    GENERAL
0007 %
0008 %      points= apply_perturbation_to_points (points, offset_extent)
0009 %
0010 %    INPUT/S
0011 %
0012 %      -points
0013 %         The points defining the CPS warp
0014 %
0015 %      -offset entent
0016 %         Defines the amount of noise/distortion
0017 %
0018 %      -perturbation_method
0019 %         The method of applying the change
0020 %
0021 %    OUTPUT/S
0022 %
0023 %      -points
0024 %         The points after offset application
0025 %
0026 %    PENDING WORK
0027 %
0028 %      -
0029 %
0030 %    KNOWN BUG/S
0031 %
0032 %      -
0033 %
0034 %    COMMENT/S
0035 %
0036 %      -
0037 %
0038 %    RELATED FUNCTION/S
0039 %
0040 %
0041 %
0042 %    ABOUT
0043 %
0044 %      -Created:     March 10th, 2004
0045 %      -Last update: April 11st, 2004
0046 %      -Revision:    0.0.6
0047 %      -Author:      R. S. Schestowitz, University of Manchester
0048 % ==============================================================
0049 
0050 
0051 if (strcmp(perturbation_method, 'random noise')),
0052  for i=1:size(points,2),
0053   points(i) = points(i) + offset_extent * (rand - 0.5) * 0.1;
0054 %   if (points(i) < 0),
0055 %      points(i) = 0;
0056 %         % make 0 a lower boundary
0057 %   end
0058 %   points = average_smooth(points,5);
0059  end
0060  
0061  
0062 elseif (strcmp(perturbation_method, 'CPS warp')),
0063 %   warp_params.green = 'biharmCPS';
0064 %   initial_warp_points = [0.1,0.2,0.3,0.4];
0065 %   shifted_warp_points = f(initial_warp_points)
0066 %   points = nrr_trans_1d(points, initial_warp_points, shifted_warp_points, warp_params, []);
0067   centre = 0.5 + rand * 0.1; % 0.1 * offset_extent * rand;
0068      % offset extend should preferably lie in the range of 1-10
0069   radius = 0.3; % 0.4 - (abs(centre - 0.5) * 2);
0070      % this chooses high legal radius
0071   points = cps_warp_1d(points, centre, radius, 0.5 * rand);
0072   
0073 else
0074   error('Unknown perturbation method');
0075 end