EP0197940A1 - Colour saturation control circuit - Google Patents

Colour saturation control circuit

Info

Publication number
EP0197940A1
EP0197940A1 EP85902612A EP85902612A EP0197940A1 EP 0197940 A1 EP0197940 A1 EP 0197940A1 EP 85902612 A EP85902612 A EP 85902612A EP 85902612 A EP85902612 A EP 85902612A EP 0197940 A1 EP0197940 A1 EP 0197940A1
Authority
EP
European Patent Office
Prior art keywords
signals
colour
rgb
deriving
signal
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Withdrawn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
EP85902612A
Other languages
German (de)
French (fr)
Inventor
Michael John Gay
Anthony David Newton
Terence Leslie O'neal
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.)
Motorola Solutions Inc
Original Assignee
Motorola Inc
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 Motorola Inc filed Critical Motorola Inc
Publication of EP0197940A1 publication Critical patent/EP0197940A1/en
Withdrawn legal-status Critical Current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
    • H04N9/64—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
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G1/00—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data
    • G09G1/28—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using colour tubes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
    • G09G5/02—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the way in which colour is displayed
    • 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
    • H04N9/67—Circuits for processing colour signals for matrixing

Definitions

  • This Invention relates to the processing of colour video signals and particularly, though not exclusively, to the processing of colour video signals in video monitors and television receivers.
  • the input signals may be in the form of red, green and blue (RGB) signals, e.g. from a camera.
  • RGB signals are derived from a composite input signal.
  • a video signal colour saturation control circuit comprises: means for receiving RGB video signals; means for deriving from the received RGB signals luminance and colour difference signals and for variably controlling the level of the colour difference signals so as to control the colour saturation; and means for deriving from the controlled colour difference signals RGB signals which are thereby saturation controlled.
  • a saturation circuit includes first, second and third input nodes 1, 2 and 3 respectively.
  • the input node 1 1s connected through a buffer amplifier 4 and through a series-connected resistor 5 to a point 6.
  • the input node 2 is connected through a buffer amplifier 7 and a series-connected resistor 8 to the point 6.
  • the input node 3 is connected through a buffer amplifier 9 and a series-connected resistor 10 to the point 6.
  • the common point 6 is also connected to the inverting inputs of two variable gain differential amplifiers 11, 12.
  • the output of the buffer amplifier 4 is connected to the non-inverting input of the differential amplifier 11.
  • the output of the buffer amplifier 9 is connected to the non-inverting input of the differential amplifier 12.
  • the non-inverting output of the differential amplifier 11 is connected to a first input of an adder 13.
  • the inverting outputs of the differential amplifiers 11 and 12 are connected to a resistor network 14, the output of which is connected to a first input of an adder 15.
  • the now inverting output of the differential amplifier 12 is connected to a first input of an adder 16. Second inputs of each of the adders 13, 15, 16 are connected via a unity-gain buffer amplifier 17 to the common point 6.
  • the outputs of the adders 13, 15 and 16 are connected respectively to output nodes 18, 19 arvd 20.
  • G and B signals are applied to the input nodes 1, 2 and 3 respectively.
  • the R signal is applied directly from the output of the buffer amplifier 4 to the non-inverting input of the differential amplifier 11.
  • the B signal is applied directly from the output of the buffer amplifier 9 to the non-inverting input of the differential amplifier 12.
  • the resistors 4, 8 and 10 have values of 3.33k , 1.69k and 9.1 so that the RGB signals are combined 1n the correct proportions at point 6 so as to produce a luminance signal Y in accordance with the well-known equation:
  • E Y 0.3 E R + 0.59 E G + 0.11 E B .
  • the output of the differential amplifier 11 is a (R-Y) signal and the output of the differential amplifier 12 is a (R-Y) signal.
  • the outputs of the differential amplifiers 11 and 12 are combined in the resistive network 14 to produce at the output of the network a (G-Y) signal in accordance with the well-known equation:
  • E G - E Y - 0.51 (E R - E Y ) - 0.186 (E B - Ey).
  • the (R-Y), (G-Y) and (B-Y) signals are combined in the adders 13, 15 and 16 respectively with the Y signal from the point 6 so as to produce R,G and B signals which appear at the output nodes 18, 19 and 20 respectively.
  • the magnitudes of the (R-Y), (G-Y) and (B-Y) signals applied to the adders 13, 15 and 16 may be varied, thus varying the colour saturation of the colour output signals R, G and B produced at the output nodes 18, 19 and
  • the (G-Y) signal may alternatively be derived by using a third differential amplifier having Its non-inverting input connected to the output of buffer a plifer 7 and having its inverting input connected to the point 6.
  • the above described television receiver control circuit could also be used in any video apparatus, e.g. a video monitor.
  • control circuit may conveniently be incorporated in an integrated circuit.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Processing Of Color Television Signals (AREA)

Abstract

Circuit de régulation de la saturation des couleurs de signaux vidéo comportant: des mécanismes (1, 2, 3) pour recevoir des signaux vidéo rouges, verts et bleus, des mécanismes (4, 7, 9, 5, 8, 10, 11, 12, 14) pour dériver des signaux rouges, verts et bleus reçus des signaux de luminance et de couleurs différentes et pour réguler de manière variable le niveau des signaux de couleurs différentes afin de réguler la saturation des couleurs; et des mécanismes (13, 15, 16) pour dériver des signaux régulés de couleurs différentes des signaux rouges, verts et bleus dont la saturation est ainsi régulée.A circuit for regulating the saturation of the colors of video signals comprising: mechanisms (1, 2, 3) for receiving red, green and blue video signals, mechanisms (4, 7, 9, 5, 8, 10, 11, 12, 14) for deriving red, green and blue signals received from signals of different luminance and colors and for variably regulating the level of the signals of different colors in order to regulate color saturation; and mechanisms (13, 15, 16) for deriving regulated signals of colors different from the red, green and blue signals, the saturation of which is thus regulated.

Description

COLOUR SATURATION CONTROL CIRCUIT
This Invention relates to the processing of colour video signals and particularly, though not exclusively, to the processing of colour video signals in video monitors and television receivers.
In use of a colour video monitor the input signals may be in the form of red, green and blue (RGB) signals, e.g. from a camera. In a television receiver RGB signals are derived from a composite input signal.
It is an object of this invention to provide a saturation control circuit whereby the colour saturation of RGB signals may be varied.
In accordance with the invention a video signal colour saturation control circuit comprises: means for receiving RGB video signals; means for deriving from the received RGB signals luminance and colour difference signals and for variably controlling the level of the colour difference signals so as to control the colour saturation; and means for deriving from the controlled colour difference signals RGB signals which are thereby saturation controlled.
One television receiver saturation control circuit in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawing which shows a block schematic diagram of the circuit.
Referring now to the drawing, a saturation circuit includes first, second and third input nodes 1, 2 and 3 respectively.
The input node 1 1s connected through a buffer amplifier 4 and through a series-connected resistor 5 to a point 6. The input node 2 is connected through a buffer amplifier 7 and a series-connected resistor 8 to the point 6. The input node 3 is connected through a buffer amplifier 9 and a series-connected resistor 10 to the point 6.
The common point 6 is also connected to the inverting inputs of two variable gain differential amplifiers 11, 12. The output of the buffer amplifier 4 is connected to the non-inverting input of the differential amplifier 11. The output of the buffer amplifier 9 is connected to the non-inverting input of the differential amplifier 12. The non-inverting output of the differential amplifier 11 is connected to a first input of an adder 13. The inverting outputs of the differential amplifiers 11 and 12 are connected to a resistor network 14, the output of which is connected to a first input of an adder 15. The now inverting output of the differential amplifier 12 is connected to a first input of an adder 16. Second inputs of each of the adders 13, 15, 16 are connected via a unity-gain buffer amplifier 17 to the common point 6.
The outputs of the adders 13, 15 and 16 are connected respectively to output nodes 18, 19 arvd 20. In use of the circuit R, G and B signals are applied to the input nodes 1, 2 and 3 respectively. The R signal is applied directly from the output of the buffer amplifier 4 to the non-inverting input of the differential amplifier 11. The B signal is applied directly from the output of the buffer amplifier 9 to the non-inverting input of the differential amplifier 12.
The resistors 4, 8 and 10 have values of 3.33k , 1.69k and 9.1 so that the RGB signals are combined 1n the correct proportions at point 6 so as to produce a luminance signal Y in accordance with the well-known equation:
EY = 0.3 ER + 0.59 EG + 0.11 EB.
Thus the output of the differential amplifier 11 is a (R-Y) signal and the output of the differential amplifier 12 is a (R-Y) signal. The outputs of the differential amplifiers 11 and 12 are combined in the resistive network 14 to produce at the output of the network a (G-Y) signal in accordance with the well-known equation:
EG - EY = - 0.51 (ER - EY) - 0.186 (EB - Ey).
The (R-Y), (G-Y) and (B-Y) signals are combined in the adders 13, 15 and 16 respectively with the Y signal from the point 6 so as to produce R,G and B signals which appear at the output nodes 18, 19 and 20 respectively.
By varying the gains of the differential amplifers 11 and 12, the magnitudes of the (R-Y), (G-Y) and (B-Y) signals applied to the adders 13, 15 and 16 may be varied, thus varying the colour saturation of the colour output signals R, G and B produced at the output nodes 18, 19 and
20 respectively.
It will be understood that the gains of the differential amplifiers 11 and 12, which control saturation of the circuit, may be controlled by a microprocessor (not shown).
It will be appreciated that if desired, instead of deriving the (G-Y) signal by a resistive network using the (R-Y) and (B-Y) signals as described above, the (G-Y) signal may alternatively be derived by using a third differential amplifier having Its non-inverting input connected to the output of buffer a plifer 7 and having its inverting input connected to the point 6. It will be appreciated that the above described television receiver control circuit could also be used in any video apparatus, e.g. a video monitor.
It will also be appreciated that the above described control circuit may conveniently be incorporated in an integrated circuit.

Claims

CLA IMS
1. A video signal colour saturation control circuit comprising: means for receiving RGB video signals; means for deriving from the received RGB signals luminance and colour difference signals and for variably controlling the level of the colour difference signals so as to control the colour saturation; and means for deriving from the controlled colour difference signals RGB signals which are thereby saturation controlled.
2. A circuit according to claim 1 wherein the means for deriving luminance and colour difference signals comprises buffer and combiner means for combining the received RGB in such proportions as to produce a luminance signal.
3. A circuit according to claim 2 wherein the means for deriving luminance and colour difference signals further comprises: first differential amplifier means for receiving the luminance signal and a first one of the RGB signals and for producting a first level controlled signal representative of their difference; second differential amplifier means for receiving the luminance signal and a second one of the RGB signals and for producing a second level controlled signal representative of their difference; and combiner means for combining the colour difference signals from the first and second differential amplifier means in such proportions as to produce a third level controlled colour difference signal reprsentative of the difference between the luminance signal and the third on of the RGB signals.
4. A circuit according to claim 1, 2 or 3 wherein the means for deriving comprise first, second and third summing means for receiving the luminance signal and respective ones of the level controlled colour difference signals and summing to produce saturation controlled RGB signals.
5. An integrated circuit incorporating a circuit according to any preceding claim.
6. A video display apparatus including a circuit according to any one of claims 1 to 4.
EP85902612A 1984-06-06 1985-06-06 Colour saturation control circuit Withdrawn EP0197940A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB848414450A GB8414450D0 (en) 1984-06-06 1984-06-06 Saturation control circuit
GB8414450 1984-06-06

Publications (1)

Publication Number Publication Date
EP0197940A1 true EP0197940A1 (en) 1986-10-22

Family

ID=10562021

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85902612A Withdrawn EP0197940A1 (en) 1984-06-06 1985-06-06 Colour saturation control circuit

Country Status (5)

Country Link
EP (1) EP0197940A1 (en)
JP (1) JPS61502439A (en)
KR (1) KR860700176A (en)
GB (1) GB8414450D0 (en)
WO (1) WO1985005718A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5077602A (en) * 1990-02-15 1991-12-31 Eastman Kodak Company Color difference compressor
JP2007503148A (en) * 2003-08-18 2007-02-15 コーニンクレッカ　フィリップス　エレクトロニクス　エヌ　ヴィ Modified intensity weights for saturation adjustment
WO2006073569A1 (en) * 2004-12-31 2006-07-13 Thomson Licensing Rgb to yprpb converter

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2543218A1 (en) * 1975-09-27 1977-04-07 Bosch Gmbh Robert SYSTEM FOR THE INDEPENDENT CORRECTION OF THE COLOR BALANCE BETWEEN THE COLOR VALUE SIGNALS OF A COLOR SIGNAL SOURCE

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8505718A1 *

Also Published As

Publication number Publication date
GB8414450D0 (en) 1984-07-11
WO1985005718A1 (en) 1985-12-19
KR860700176A (en) 1986-03-31
JPS61502439A (en) 1986-10-23

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Inventor name: O'NEAL, TERENCE, LESLIE

Inventor name: NEWTON, ANTHONY, DAVID

Inventor name: GAY, MICHAEL, JOHN