How to perform wavelet decomposition HPF and LPF on image separately
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I am having degraded image.here i need to separate high frequency information and low frequency information from the image by choosing different decomposition level from 1 to 8 and daubechies db8.
I have done like this but from this i can able to separate only low frequency information for 8 levels.
I=imread('img.jpg');
[Lo_D,Hi_D,Lo_R,Hi_R]=wfilters('db8');
[C,S]=wavedec2(I,8,Lo_D,Hi_D);
LF1=wrcoef2('a',C,S,'db8',1);
LF2=wrcoef2('a',C,S,'db8',2);
. .
LF8=wrcoef2('a',C,S,'db8',8);
imshow(uint8(LF1));
Does any one know how to extract high frequency information from the image or is any other method to do the same?
thank you
답변 (1개)
Wayne King
2013년 2월 28일
If you want to generate projections onto the wavelet subspaces similar to the one onto the approximation subspace you have above, then replace 'a' by appropriate detail space
X = wrcoef2('h',C,S,'wname',N); % for horizontal
X = wrcoef2('d',C,S,'wname',N); % for diagonal
and obviously 'v' for vertical.
The separable filtering operations are as follows:
The horizontal image is LH (lowpass rows and highpass columns). The vertical image is HL (highpass rows and lowpass columns) The diagonal image is HH (highpass rows then highpass columns)
Note that these projections are not the wavelet coefficients. The wavelet coefficients you can obtain with:
[H,V,D] = detcoef2('all',C,S,N);
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