IEG4160_Part6 - IEG 4160: Image and Video Processing....

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Image Enhancement in Frequency Domain IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu Spectrum of images Filtering in frequency domain Lowpass filtering Highpass filtering Homomorphic filtering
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 2 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Spectrum of images Discrete Fourier transform pair ( u , v ): frequency domain F ( u , v ): frequency component | F ( u , v )|: frequency spectrum 11 2( / / ) 00 1 (,) (, ) 0,1,. .., 1; .., 1 MN ju x M v y N xy Fuv f xye MN uM vN π −+ == = = −= ∑∑ .., 1; .., 1 x M v y N uv fxy Fuve xM yN + = =
Background image of page 2
Page 3 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Spectrum of images (,) ( , ) : s ymmetric; the spectrum is centered on the origin Fuv F u v = −− u v (0,0) M -1 N -1 Low frequency components High frequency components F ( u , v ) (/ 2 , / 2 ) Fu M v N (0,0) v u M -1 N -1 ( , )( 1) x y fxy + 2 , / 2 ) F uM vN 8
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 4 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Spectrum of images Example 1 (,) (1 ) ( /2 , ) xy fxy Fu M v N + ⇔− (after log transformation) (0,0) (0,0)
Background image of page 4
Page 5 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Spectrum of images Example 2 ± : the average gray level of an image ± Low frequencies: close to the center; corresponding to slowly varying components of an image ± High frequencies: away from the center; corresponding to fast gray level changes in an image 11 2( / / ) 00 1 (,) (, ) MN ju x M v y N xy Fuv f xye MN π −− −+ == = ∑∑ 1 (0,0) ( , ) F fxy MN = Image c is sharper than image a showing more high frequencies in the spectrum (electron micrographs)
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 6 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Spectrum of images Example 3 ± Strong edges run at strong frequency components along ± Two white oxide protrusions vertical component off-axis slightly to the left 45 ≈ ± D 45 ± D
Background image of page 6
Page 7 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Filtering in frequency domain 0 (,) (1 ) x y fx y f x y + = (, ) Fuv f x y (,) (,) FuvHuv 1 f x y 1 ) x y y + ( ) : a f i l t e r Huv 0 f x y Basic filtering in frequency domain g x y
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 8 IEG 4160: Image and Video Processing. Lecturer: Jianzhuang Liu 6. Image Enhancement in Frequency Domain Lowpass filtering Ideal lowpass filters 0 0 1 if ( , ) (,) 0 if ( , ) Duv D Huv D = > 22 ( , ) ( /2) ( u M v N =− + cutoff frequency
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/13/2009 for the course CS 5150 taught by Professor Xulei during the Spring '09 term at University of Central Arkansas.

Page1 / 35

IEG4160_Part6 - IEG 4160: Image and Video Processing....

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online