Image Enhancement in the Frequency Domain Part II

1
Image Enhancement in theFrequency DomainPart II

• Dr. Samir H. Abdul-Jauwad
• Electrical Engineering Department
• King Fahd University of Petroleum Minerals

2
Gaussian Lowpass Filter

• D(u,v) distance from the origin of FT
• Parameter ?D0 (cutoff frequency)
• The inverse FT of the Gaussian filter is also a
  Gaussian

3
Image Enhancement in the Frequency Domain
4
(No Transcript)
5
Image Enhancement in the Frequency Domain
6
Image Enhancement in the Frequency Domain
7
Image Enhancement in the Frequency Domain
8
Sharpening (Highpass) Filtering

• Image sharpening can be achieved by a highpass
  filtering process, which attenuates the
  low-frequency components without disturbing
  high-frequency information.
• Zero-phase-shift filters radially symmetric and
  completely specified by a cross section.

9
(No Transcript)
10
Ideal Filter (Highpass)

• This filter is the opposite of the ideal lowpass
  filter.

11
Butterworth Filter (Highpass)

• High-frequency emphasis Adding a constant to a
  highpass filter to preserve the low-frequency
  components.

12
Gaussian Highpass Filter

• D(u,v) distance from the origin of FT
• Parameter ?D0 (cutoff frequency)

13
Laplacian (recap)
14
Laplacian in the FD

• It can be shown that
• The Laplacian can be implemented in the FD by
  using the filter
• FT pair

15
Laplacian in the Frequency Domain