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In
Ib = Io @ h + n
@ is used to denote 2D convolution.
where Io is the original image (unknown), h is the blurring filter, Ib
is the blurred image and n is the noise, respectively. What we have
known is Ib, h and the mean mu and variance sigma of n. Io is to be
reconstructed. The so-called Philips method based on smoothing
reconstructs Io by minimising the following constraint least square
function
2 2 2
J(Ioe) = ||Q * Ioe|| + alpha * (|| Ib - h @ Ioe|| - ||n|| )
where alpha is a constant, Ioe is the reconstructed Io, and
2 2 2
||n|| = (M - 1)(N - 1) * [mu + sigma ]
The frequency response of Ioe is (for each Hioe(w1, w2))
T
H (w1, w2) * Hb(w1, w2)
Hioe(w1, w2) = ---------------------------------------
2 2
|H(w1, w2)| + (1/alpha) * |Hp(w1, w2)|
where T denotes complex conjugate, and Hp is just the frequency
response of 2D Laplacian operator hp, that is,
0 1 0
hp = 1 -4 1
0 1 0
Then Ioe can be gained by doing inverse Fourier transform of Hioe.
Now, alpha needs to be adjusted to satisfy
2 2
|| Ib - h @ Ioe|| = ||n||
So how to determine alpha? Is there any algorithm to solve it? Is it
sole or multiple?
Thanks a lot!!!
With Kindly Regards,
Theron
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