EP0470109A1 - Circuit pour le traitement d'un signal de luminance - Google Patents

Circuit pour le traitement d'un signal de luminance

Info

Publication number
EP0470109A1
EP0470109A1 EP90906197A EP90906197A EP0470109A1 EP 0470109 A1 EP0470109 A1 EP 0470109A1 EP 90906197 A EP90906197 A EP 90906197A EP 90906197 A EP90906197 A EP 90906197A EP 0470109 A1 EP0470109 A1 EP 0470109A1
Authority
EP
European Patent Office
Prior art keywords
signal
circuit
luminance signal
circuit according
comb filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90906197A
Other languages
German (de)
English (en)
Inventor
Hans-Jürgen Kluth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Deutsche Thomson Brandt GmbH
Original Assignee
Deutsche Thomson Brandt GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Deutsche Thomson Brandt GmbH filed Critical Deutsche Thomson Brandt GmbH
Publication of EP0470109A1 publication Critical patent/EP0470109A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/77—Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/77—Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase
    • H04N9/78—Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase for separating the brightness signal or the chrominance signal from the colour television signal, e.g. using comb filter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/646—Circuits for processing colour signals for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/68—Circuits for processing colour signals for controlling the amplitude of colour signals, e.g. automatic chroma control circuits

Definitions

  • Video devices are known, e.g. S-VHS video recorders, improved television receivers for reproducing the signals of such recorders or so-called HDTV television receivers, which have an increased quality of the reproduced picture.
  • a higher bandwidth of the luminance signal of approximately 5.5 MHz and thus an increase in image sharpness in the horizontal direction are achieved in such devices.
  • Devices of this type require additional circuits for processing and processing the signals, in particular the luminance signal.
  • Comb filters have the advantage over a conventional bandpass filter that they have periodically recurring passages in the spectral components of the desired signal and corresponding blocking points in the spectral components of the signal to be eliminated.
  • So-called crispening circuits are known to increase the sharpness of the image in the horizontal direction, although none Increasing the bandwidth of the luminance signal, however, controlling signal jumps and thus increasing the sharpness of the image, in particular in the case of fine image details.
  • a correction signal is added to the luminance signal, for example, which is obtained by double differentiation, each with a subsequent amplitude limitation.
  • the amplitude of the correction signal added to the luminance signal is limited, since otherwise disturbances in the form of flickering occur in particular as a result of crosstalk from the color channel with vertical picture edges.
  • the invention has for its object to provide a circuit for processing the luminance signal, which brings about an effective improvement in the luminance signal with regard to separation of the luminance signal from the color carrier and increase in image sharpness.
  • the combination according to the invention of two circuits known per se results in a surprisingly effective and clearly perceptible improvement in the image reproduction.
  • the task of the comb filter is to reduce signal residues of the color carrier in the luminance signal to a minimum and thereby keep the crosstalk of the color carrier into the luminance signal, which leads to color flicker at high frequencies of the luminance signal, as low as possible.
  • the circuit for increasing the sharpness of the image however, additionally effects a control of signal jumps, ie an increase in the sharpness of the image in the horizontal direction.
  • Fig. 1 shows a first embodiment with a
  • Fig. 2 shows a second embodiment with a
  • Terminal 23 is fed via inputs T1, line 24, delay line 25, and transistor T3, which functions as an emitter follower, to inputs 12, 13 of integrated circuit 26, which is a comb filter.
  • the delay line 25 has a delay time of 620 ns and is used to compensate for the delay between the luminance signal Y and the color carrier F.
  • the delay line 25 acts as a low-pass filter with a cut-off frequency of 6 MHz.
  • the circuit 26 is of the type VC2063 from JVC.
  • the delay lines VL1 and VL2 necessary for the function as a PAL comb filter are connected to the terminals 18, 19 and 20, 22 of the circuit 26.
  • the delays Cable lines VL1 and VL2 each cause a delay of two lines. The exact delay time is 127.889 ⁇ s.
  • the band filter 35 with a pass band of 4.43 MHz ⁇ 500 kHz with a delay time of 420 ns is connected to the terminals 5, 6.
  • the low-pass filter 36 with a limit frequency of 6 MHz and the delay time of 385 ns is connected to the terminal 4 of the circuit 26, the output of which is connected to the terminal 3 of the circuit 26 via the transistor T2, which works as an emitter follower.
  • the modulated color carrier F reaches the terminal 1 of the circuit 26 from the emitter of the transistor T1 via the bandpass 37 with a pass band of 4.43 MHz ⁇ 1 MHz and a group delay of 190 ns.
  • the circuit 26 forms a comb filter together with the peripheral components K, which has periodic blocking points and pass-through points for the luminance signal Y and the modulated color carrier F.
  • the comb filter K supplies the luminance signal Y at the output 27, which is freed from the color carrier by the action of the comb filter.
  • the comb filter K supplies the modulated color carrier F, which is largely free of the luminance signal and is supplied to a color channel (not shown in more detail).
  • the comb filter K can work analog or digital. Such comb filters for a PAL signal are described in the earlier patent applications P 38 33 692 and P 38 36 043.
  • the output 27 of the comb filter K is connected to the input 29 of the so-called crispening circuit C to increase the image sharpness in the horizontal direction.
  • the luminance signal Y reaches the transistor T5 via the transistor T4 operating as an emitter follower.
  • a coil L1 which differentiates the signal Y, is located in its collector circuit.
  • the diode circuit D1 which effects an amplitude limitation of the signal Y once differentiated, is connected in parallel with L1.
  • the signal Y, once differentiated passes through the transistor T6 working as an emitter follower to the transistor T7.
  • the coil L2 In its collector circuit is the coil L2, which causes a second differentiation of the signal.
  • the diode circuit D2 limits the amplitude of the twice differentiated signal Y.
  • the correction voltage Uk thus obtained reaches the circuit point 30 at the base of the transistor T10 via the transistor T8, and the transistor T4 on the other hand via the delay stage 31 serving to compensate for the delay and the transistor T9 the luminance signal Y is supplied.
  • the correction signal Uk is added to the luminance signal Y to increase the sharpness of the image.
  • the luminance signal Yk corrected with regard to image sharpness reaches output 32 via transistor T12 and is available there as corrected luminance signal Yk with increased image sharpness in the horizontal direction.
  • the amplitude of the signal can be adjusted with the potentiometer 33 to the desired value of, for example, 1 Vpp.
  • Such a crispening circuit is described in more detail in EP-PS 00 77 010.
  • the amplitude of the correction signal Uk and thus the measure of the sharpness increase can be adjusted with the potentiometer 34. Due to the effect of the comb filter K, which results in an optimal separation of Y and F without any noteworthy color carrier residues in Y, the amplitude Uk and thus the degree of sharpness increase can be set to a higher value than with a luminance signal Y that is not with a comb filter, but was freed from the ink carrier F with a conventional band filter. The flickering at the black-and-white transitions due to ink carrier residues is greatly reduced.
  • FIG. 2 shows an embodiment in which the correction signal is obtained from the luminance signal with a cosine equalizer.
  • FIG. 3 shows at which points in FIG. 2 the signals a to g are located.
  • the luminance signal Y is assumed to be a rectangular pulse a).
  • the two adding stages 1, 2 of the comb filter K supply the luminance signal Y and the color carrier F. Y passes through the amplifier 2 and the resistor
  • undelayed signal passes through amplifier 5 to subtractor 6, which on the other hand is supplied with delayed signal d via amplifier 7.
  • the output signal e is fed to the threshold value stage 8.
  • Stage 8 only allows signal amplitudes that are above a positive and below a negative threshold value. This suppresses low-amplitude interference signals.
  • the circuit 8 is preferably formed by two antiparallel connected diodes in the signal path.
  • the correction signal Uk is produced, which reaches adder 9.
  • the undelayed luminance signal Y according to curve c is also fed to the adder 9 via the delay line 31 and the amplifier 10.
  • the delay line 31 is used to adapt to the signal delay introduced by the delay line 4 so that the signals Uk and f at the inputs of the adder 9 coincide in time.
  • the output signal g of the adder 9 passes through the amplifier 11 to the output terminal 32, at which the corrected luminance signal Yk is available according to the curve g in FIG. 3.
  • the delay time of the run time lines 4, 31 is 125, ns.
  • the delay of the reflected signal at the input of line 4 is thus 250 ns.
  • the color carrier is fed via the amplifier 12, the delay line 13 and the amplifier 14 to the terminal 28, at which the color carrier is available separately from the luminance signal Y.
  • Line 13 also has a delay time of 125 ns and is used to adapt to the transit times in the way of the luminance signal, essentially due to the delay lines 4, 31.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)
  • Picture Signal Circuits (AREA)

Abstract

L'invention a pour but de fournir un circuit pour le traitement d'un signal de luminance, permettant d'obtenir une amélioration optimale de ce signal en ce qui concerne notamment l'acuité de l'image et la séparation des sous-porteuses couleur. Le signal FBAS (signal complet de chrominance) est envoyé à un filtre-peigne (K) adaptatif. Sa sortie est reliée à l'entrée d'un circuit pour l'accroissement de l'acuité de l'image, présentant deux étages de différenciation ayant chacun un circuit limiteur d'amplitude ou un correcteur de cosinus. Le circuit est utilisé en particulier pour un magnétoscope S-VHS ou un récepteur de télévision.
EP90906197A 1989-04-27 1990-04-19 Circuit pour le traitement d'un signal de luminance Withdrawn EP0470109A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3913916 1989-04-27
DE3913916 1989-04-27
DE3940128 1989-12-05
DE3940128A DE3940128A1 (de) 1989-04-27 1989-12-05 Schaltung zur aufbereitung eines leuchtdichtesignals

Publications (1)

Publication Number Publication Date
EP0470109A1 true EP0470109A1 (fr) 1992-02-12

Family

ID=25880346

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90906197A Withdrawn EP0470109A1 (fr) 1989-04-27 1990-04-19 Circuit pour le traitement d'un signal de luminance

Country Status (7)

Country Link
EP (1) EP0470109A1 (fr)
JP (1) JPH04504937A (fr)
KR (1) KR920702164A (fr)
AU (1) AU5442790A (fr)
DE (1) DE3940128A1 (fr)
HU (1) HUT61427A (fr)
WO (1) WO1990013209A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4050084A (en) * 1976-07-14 1977-09-20 Cbs Inc. Comb filter for television signals having adaptive features
DE2718353A1 (de) * 1977-04-25 1978-10-26 Faroudja Y C Verfahren und vorrichtung zur herabsetzung der uebergangszeit bei der fernsehbildwiedergabe zur verbesserung der bildschaerfe bzw. der goldmark-versteilerung
US4386434A (en) * 1981-06-08 1983-05-31 Rca Corporation Vertical and horizontal detail signal processor
DE3269852D1 (en) * 1981-10-14 1986-04-17 Telefunken Fernseh & Rundfunk Circuit for reducing the rise-time of the flanks of a video signal, in particular for a video recorder
DE3521991A1 (de) * 1985-06-20 1987-01-02 Thomson Brandt Gmbh Schaltung zur verbesserung der wiedergabe-bildschaerfe in einem videorecorder

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9013209A1 *

Also Published As

Publication number Publication date
DE3940128A1 (de) 1990-10-31
AU5442790A (en) 1990-11-16
JPH04504937A (ja) 1992-08-27
WO1990013209A1 (fr) 1990-11-01
HU903470D0 (en) 1992-01-28
KR920702164A (ko) 1992-08-12
HUT61427A (en) 1992-12-28

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