GB1236377A - Improvements relating to non-linear function generators - Google Patents

Improvements relating to non-linear function generators

Info

Publication number
GB1236377A
GB1236377A GB4026067A GB4026067A GB1236377A GB 1236377 A GB1236377 A GB 1236377A GB 4026067 A GB4026067 A GB 4026067A GB 4026067 A GB4026067 A GB 4026067A GB 1236377 A GB1236377 A GB 1236377A
Authority
GB
United Kingdom
Prior art keywords
voltage
representing
function
inverting
amplifier
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.)
Expired
Application number
GB4026067A
Inventor
Peter Charles Pugsley
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.)
Crosfield Electronics Ltd
Original Assignee
Crosfield Electronics Ltd
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 Crosfield Electronics Ltd filed Critical Crosfield Electronics Ltd
Priority to GB4026067A priority Critical patent/GB1236377A/en
Priority to DE19681774772 priority patent/DE1774772C3/en
Publication of GB1236377A publication Critical patent/GB1236377A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/12—Arrangements for performing computing operations, e.g. operational amplifiers
    • G06G7/26—Arbitrary function generators
    • G06G7/28—Arbitrary function generators for synthesising functions by piecewise approximation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • H04N1/4072—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on the contents of the original
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46—Colour picture communication systems
    • H04N1/56—Processing of colour picture signals
    • H04N1/60—Colour correction or control
    • H04N1/6027—Correction or control of colour gradation or colour contrast

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Theoretical Computer Science (AREA)
  • Software Systems (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Facsimile Image Signal Circuits (AREA)
  • Facsimile Heads (AREA)

Abstract

1,236,377. Analogue function generators. CROSFIELD ELECTRONICS Ltd. 3 Sept., 1968 [4 Sept., 1967], No. 40260/67. Heading G4G. [Also in Division H4] A function generator, e.g. for colourtone correction receives an analogue voltage x representing, e.g. a colour component to produce a voltage z representing f (x, y) from which a function generator produces a voltage representing F(z) having zero value for at least two values of z corresponding, e.g. to " black " and "first printing" tone values; a variable attenuator responsive to F(z) producing a signal #F(Z) which is combined with a signal representing a multiple mx of the input voltage to generate a voltage representing y. Voltage x is applied (Fig. 1) to summation amplifier A, also receiving voltage y fed back from the output to produce voltage (x+y) from which triple function generator x 1 , x 2 , x 3 produces function voltages # 1 (x+y), # 2 (x+y), # 3 (x+y). Voltage # 1 (x+y) is applied over attentuator # centre tapped to ground to produce voltage # #1 (x + y) applied alternatively to direct and inverting inputs of summation amplifier A 2 also receiving attentuated input voltage x, so that the output y is given by x+## 1 (x+y) (Fig. 2, not shown); a family of curves dependent on #, symmetrical about (y - x) = 0, and intersecting points P, Q at which # 1 (x+y) is zero. The function generator (Fig. 3) comprises an inverting amplifier A 3 generating a voltage to represent 2 - (x + y) applied to resistance-diode networks synthesizing a piecewise-linear function (Fig. 4) whose voltage is buffered by emitter follower T 1 applying voltage # 1 (x+y) to tapped resistor chain attentuator R with two position switch S 1 , S 2 selecting signals for the direct or inverting inputs of amplifier A 2 (Fig. 5, not shown) comprising two inverting operational amplifiers with virtual earth, and direct or inverting summing inputs; also receiving signals from the function generators x 2 , x 3 . The attentuation controls may then separately regulate, e.g. highlight contrast mid-tone density, and shadow contrast in either sense.
GB4026067A 1967-09-04 1967-09-04 Improvements relating to non-linear function generators Expired GB1236377A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB4026067A GB1236377A (en) 1967-09-04 1967-09-04 Improvements relating to non-linear function generators
DE19681774772 DE1774772C3 (en) 1967-09-04 1968-09-03 Tonal correction circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB4026067A GB1236377A (en) 1967-09-04 1967-09-04 Improvements relating to non-linear function generators

Publications (1)

Publication Number Publication Date
GB1236377A true GB1236377A (en) 1971-06-23

Family

ID=10414010

Family Applications (1)

Application Number Title Priority Date Filing Date
GB4026067A Expired GB1236377A (en) 1967-09-04 1967-09-04 Improvements relating to non-linear function generators

Country Status (1)

Country Link
GB (1) GB1236377A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2450472A1 (en) * 1979-02-28 1980-09-26 Fuji Photo Film Co Ltd GRADATION IMAGE PROCESSING METHOD AND APPARATUS FOR RADIATION IMAGE RECORDING SYSTEM
FR2450471A1 (en) * 1979-02-28 1980-09-26 Fuji Photo Film Co Ltd GRADATION PROCESSING METHOD AND APPARATUS FOR RADIATION IMAGE RECORDING SYSTEM
EP0814602A2 (en) * 1996-06-21 1997-12-29 Hewlett-Packard Company Jitter-form background control for minimizing spurious gray cast in scanned images
NL1006472C2 (en) * 1997-07-04 1999-01-05 Oce Tech Bv Copier with adjustable gradation.
US5936741A (en) * 1990-10-02 1999-08-10 Southwest Software, Inc. Method and apparatus for calibrating image output from an image generating device
EP1365575A1 (en) * 2002-05-23 2003-11-26 GRETAG IMAGING Trading AG Method and apparatus for improving image contrast

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2450472A1 (en) * 1979-02-28 1980-09-26 Fuji Photo Film Co Ltd GRADATION IMAGE PROCESSING METHOD AND APPARATUS FOR RADIATION IMAGE RECORDING SYSTEM
FR2450471A1 (en) * 1979-02-28 1980-09-26 Fuji Photo Film Co Ltd GRADATION PROCESSING METHOD AND APPARATUS FOR RADIATION IMAGE RECORDING SYSTEM
US5936741A (en) * 1990-10-02 1999-08-10 Southwest Software, Inc. Method and apparatus for calibrating image output from an image generating device
EP0814602A2 (en) * 1996-06-21 1997-12-29 Hewlett-Packard Company Jitter-form background control for minimizing spurious gray cast in scanned images
EP0814602A3 (en) * 1996-06-21 1999-11-10 Hewlett-Packard Company Jitter-form background control for minimizing spurious gray cast in scanned images
EP1289263A2 (en) * 1996-06-21 2003-03-05 Hewlett-Packard Company Jitter-form background control for minimizing spurious gray cast in scanned images
EP1289263A3 (en) * 1996-06-21 2003-05-07 Hewlett-Packard Company Jitter-form background control for minimizing spurious gray cast in scanned images
NL1006472C2 (en) * 1997-07-04 1999-01-05 Oce Tech Bv Copier with adjustable gradation.
EP0889643A1 (en) * 1997-07-04 1999-01-07 Océ-Technologies B.V. A copying apparatus having adjustable gradation
EP1365575A1 (en) * 2002-05-23 2003-11-26 GRETAG IMAGING Trading AG Method and apparatus for improving image contrast

Also Published As

Publication number Publication date
DE1774772B2 (en) 1976-09-23
DE1774772A1 (en) 1972-01-20

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