Xem mẫu
Digital Image Processing
Image Enhancement Frequency domain methods
21/11/15 Duong Anh Duc - Digital Image Processing 1
Image Enhancement: Frequency domain methods
The concept of filtering is easier to visualize in the frequency domain. Therefore, enhancement
of image f(m,n) can be done in the frequency domain, based on its DFT F(u,v) .
This is particularly useful, if the spatial extent of the point-spread sequence h(m,n) is large. In this case, the convolution
PSS
Enhanced Image
g(m,n) = h(m,n)*f(m,n)
Given Image
may be computationally unattractive.
21/11/15 Duong Anh Duc - Digital Image Processing 2
Frequency domain methods
We can therefore directly design a transfer function H(u,v) and implement the enhancement in the frequency domain as follows: Transfer Function
Enhanced Image
G(u,v) = H(u,v)*F(u,v)
Given Image
21/11/15 Duong Anh Duc - Digital Image Processing 3
1-d Fourier transform of a sequence
Given a 1-d sequence s[k], k={…,-1,0,1,2,…,} Fourier transform
Fourier transform is periodic with 2 Inverse Fourier transform
21/11/15 Duong Anh Duc - Digital Image Processing 4
1-d Fourier transform of a sequence
How is the Fourier transform of a sequence s[k] related to the Fourier transform of the continuous signal
Continuous-time Fourier transform
21/11/15 Duong Anh Duc - Digital Image Processing 5
...
- tailieumienphi.vn
nguon tai.lieu . vn