10_fsharpenx

10_fsharpenx - We can expect IHPFs to have the same ringing...

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Sharpening Frequency-Domain Filters COMP344 COMP344 Sharpening Frequency-Domain Filters
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Concepts Edges and other abrupt changes in grey levels are associated with high-frequency components image sharpening can be achieved by using the high-pass frequency filtering process The high-pass filter attenuates (suppresses) the low-frequency components without disturbing high-frequency information in the Fourier transform Relation between low-pass and high-pass filters H hp ( u , v ) = 1 - H lp ( u , v ) COMP344 Sharpening Frequency-Domain Filters
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Ideal High Pass Filter (IHPF) This filter is the opposite of the ideal lowpass filter H ( u , v ) = ± 0 D ( u , v ) D 0 1 D ( u , v ) > D 0 D ( u , v ): distance from point ( u , v ) to the origin of the frequency plane; D ( u , v ) = ( u 2 + v 2 ) 1 / 2 D 0 : cutoff frequency (non-negative) COMP344 Sharpening Frequency-Domain Filters
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Ideal High Pass Filter
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Unformatted text preview: We can expect IHPFs to have the same ringing properties as ILPFs COMP344 Sharpening Frequency-Domain Filters High Pass Butterworth Filter H ( u , v ) = 1 1+[ D / D ( u , v ) ] 2 n cf. Low pass Butterworth filter: H ( v , u ) = 1 1+[ D ( u , v ) / D ] 2 n COMP344 Sharpening Frequency-Domain Filters High Pass Butterworth Filter. .. We can expect Butterworth highpass filters to behave smoother than IHPFs COMP344 Sharpening Frequency-Domain Filters High Pass Gaussian Filter H ( u , v ) = 1-e-D 2 ( u , v ) / 2 D 2 cf. lowpass Gaussian filter: H ( u , v ) = e-D 2 ( u , v ) / 2 D 2 COMP344 Sharpening Frequency-Domain Filters High Pass Gaussian Filter. .. COMP344 Sharpening Frequency-Domain Filters...
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10_fsharpenx - We can expect IHPFs to have the same ringing...

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