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0040 function R = bayer_demosaic(img, pattern, interpolate)
0041
0042 if (nargin < 1 || nargin > 3 || isempty(img))
0043 usage('bayer_demosaic(img, pattern, interpolate)');
0044 end
0045
0046 if (~exist('pattern','var') || isempty(pattern))
0047 pattern = access_bayer_pattern();
0048 if isempty(pattern)
0049 error(['bayer_demosaic: neither parameter pattern nor ' ...
0050 'access_bayer_pattern() are set.']);
0051 end
0052 end
0053
0054 if (~exist('interpolate','var') || isempty(interpolate))
0055 interpolate = true;
0056 end
0057
0058 if ischar(img)
0059 I = myimread(img);
0060 else
0061 I = double(img);
0062 end
0063
0064 [h, w, nd] = size(I);
0065
0066 if (nd ~= 1)
0067 error('bayer_demosaic: image data must be MxNx1.');
0068 end
0069
0070
0071
0072 bfp = mat2cell(reshape(pattern, [2,2]).', [1,1], [1,1]);
0073
0074
0075 Red = zeros(h, w);
0076 [bi,bj]=find(strcmpi(bfp, 'r'));
0077 ri = bi:2:h;
0078 cj = bj:2:w;
0079 Red(ri, cj) = I(ri, cj);
0080
0081
0082 Green1 = zeros(h, w);
0083 Green2 = Green1;
0084 [bi,bj]=find(strcmpi(bfp, 'g'));
0085 ri = bi(1):2:h;
0086 cj = bj(1):2:w;
0087 Green1(ri, cj) = I(ri, cj);
0088
0089 ri = bi(2):2:h;
0090 cj = bj(2):2:w;
0091 Green2(ri, cj) = I(ri, cj);
0092
0093
0094 Blue = zeros(h, w);
0095 [bi,bj]=find(strcmpi(bfp, 'b'));
0096 ri = bi:2:h;
0097 cj = bj:2:w;
0098 Blue(ri, cj) = I(ri, cj);
0099
0100 if (interpolate == true)
0101 Red = bayer_interp(Red);
0102 Red = bayer_interp(Red.').';
0103 Green1 = bayer_interp(Green1);
0104 Green1 = bayer_interp(Green1.').';
0105 Green2 = bayer_interp(Green2);
0106 Green2 = bayer_interp(Green2.').';
0107 Green = (Green1+Green2)/2;
0108 Blue = bayer_interp(Blue);
0109 Blue = bayer_interp(Blue.').';
0110 else
0111 Green = Green1 + Green2;
0112 end
0113
0114 R = reshape([Red Green Blue], [h w 3]);
0115
0116 end
0117
0118
0119
0120
0121
0122
0123 function Ri = bayer_interp(img_chan)
0124
0125 h = size(img_chan, 1);
0126 B = [img_chan(1:2,:); img_chan; img_chan((h-1):h,:)];
0127 Ri = filter(triang(3), 1, B);
0128 Ri = Ri(4:(4+h-1),:);
0129
0130 end
0131