apply_degradetion

PURPOSE ^

function [Id,PSF] = apply_degradetion(Im,Type,varargin);

SYNOPSIS ^

function [degraded,PSF] = apply_degradetion(Im,type,varargin);

DESCRIPTION ^

 function [Id,PSF] = apply_degradetion(Im,Type,varargin);

  INPUT:
  Im:    Image to be degraded
  Type: type of degradation to be applied. Implemented degratations are:
            'gn' :          gaussian white noise (iid)
            'blur_gn':  blur plus gaussian white noise
            'jpeg'        :   jpeq compression
            'salt_pepper': salt and pepper noise
  The number of arguments depends on the type of degradation:
      gn: the variance of the noise.
      blur_gn: the normalized frequency cut (0-1) of the low-pass filter an the variance of the noise
      jpeg: the quality of the compression (see imwrite)
      salt_pepper: noise density (see imnoise)

   OUTPUT:
   Id: degraded image
   PSF: the point spread function of the blurring (this can be just a delta function if there is no blurring).

    LocalRestorationToolbox
    See J. Gutierrez, F. Ferri and J. Malo '' IEEE TIP Jan. 2006

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 % function [Id,PSF] = apply_degradetion(Im,Type,varargin);
0002 %
0003 %  INPUT:
0004 %  Im:    Image to be degraded
0005 %  Type: type of degradation to be applied. Implemented degratations are:
0006 %            'gn' :          gaussian white noise (iid)
0007 %            'blur_gn':  blur plus gaussian white noise
0008 %            'jpeg'        :   jpeq compression
0009 %            'salt_pepper': salt and pepper noise
0010 %  The number of arguments depends on the type of degradation:
0011 %      gn: the variance of the noise.
0012 %      blur_gn: the normalized frequency cut (0-1) of the low-pass filter an the variance of the noise
0013 %      jpeg: the quality of the compression (see imwrite)
0014 %      salt_pepper: noise density (see imnoise)
0015 %
0016 %   OUTPUT:
0017 %   Id: degraded image
0018 %   PSF: the point spread function of the blurring (this can be just a delta function if there is no blurring).
0019 %
0020 %    LocalRestorationToolbox
0021 %    See J. Gutierrez, F. Ferri and J. Malo '' IEEE TIP Jan. 2006
0022 %
0023 function [degraded,PSF] = apply_degradetion(Im,type,varargin);
0024 
0025 if (strcmpi(type,'gn'))
0026 
0027    fc = 2;
0028    Val_min = 0.001;
0029 
0030    lim_frec = [0 3];
0031 
0032    variance = varargin{1}
0033 
0034    [degraded,PSF,H,noise,Blurred]=degrade(Im,fc,Val_min,lim_frec,variance);
0035 
0036 elseif  (strcmpi(type,'blur_gn'))
0037 
0038    fc = varargin{1};
0039    Val_min = 0.001;
0040 
0041    lim_frec = [0 3];
0042 
0043    variance = varargin{2};
0044 
0045    [degraded,PSF,H,noise,Blurred]=degrade(Im,fc,Val_min,lim_frec,variance);
0046 
0047 elseif  (strcmpi(type,'jpeg'))
0048 
0049    PSF = zeros(11);
0050    PSF(6,6)=1;
0051 
0052    imwrite(Im/255,'tmp.jpg','Quality',varargin{1});
0053    degraded = imread('tmp.jpg');
0054 
0055 elseif  (strcmpi(type,'salt_pepper'))
0056 
0057    PSF = zeros(11);
0058    PSF(6,6)=1;
0059    degraded = imnoise(Im/255,'salt & pepper', varargin{1});
0060    degraded = degraded*255;
0061 else
0062    error('The requested degradation is not implemented');
0063 end
0064 
0065 degraded = double(degraded);

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