Contour detecting filter

Details Contour detecting filter Contour detecting filter

1985-07-18

1987-06-30

Groody, James J.

Facsimile and static presentation processing

Static presentation processing

Attribute control

358166, 358 96, H04N 514

Patent

active

046774610

ABSTRACT:
A contour detecting filter (8, 10, 11) sequentially inputs series of sampling values obtained by sampling composite video signals, which are composed of frequency-multiplexed video luminance signals and chrominance signals and include chrominance subcarriers, at a frequency four times that of the chrominance subcarriers to detect four sampling values point-symmetrically positioned around a reference sampling value and having the same-phased chrominance subcarriers by utilizing delay circuits. The reference sampling value and the four sampling values are so employed as to perform arithmetic on second order differentiations in the direction of horizontal scanning lines and the vertical direction on the screen thereby to detect the contour signal of the reference sampling value. A contour detecting filter (12) detects contour signals in the direction of horizontal scanning lines from composite video signals utilizing a vertical low-pass filter (14) and a horizontal high-pass filter (15) which are cascade-connected with each other while detecting contour signals in the vertical direction on the screen by utilizing a vertical high-pass filter (16) and a horizontal low-pass filter (17) which are cascade-connected with each other. Switched and outputted are the contour signals in the direction of the horizontal scanning lines and the vertical direction on the screen.

REFERENCES:
patent: 4030121 (1977-06-01), Faroudja
patent: 4127873 (1978-11-01), Katagi
patent: 4331971 (1982-05-01), Bretl
patent: 4504853 (1985-03-01), Faroudja
patent: 4609938 (1986-09-01), Suzuki
"Image and its Processing; Digital Image Processing (III)", by Mikio Takagi, Journal of Japan Television Society, No. 12, vol. 29 (1975), pp. 1009-1019.
"Digital and Analog Enhancement Techniques" by Yves Faroudja et al., SMPTE Journal, vol. 87, Jan. 1978.
"Digital Picture Processing", by Azriel Rosenteld and Avinash C. Kak, vol. 1, Academic Press Inc., 1982, pp. 237-250.

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