JPS568961A - Shading correcting circuit - Google Patents

Shading correcting circuit

Info

Publication number
JPS568961A
JPS568961A JP8545179A JP8545179A JPS568961A JP S568961 A JPS568961 A JP S568961A JP 8545179 A JP8545179 A JP 8545179A JP 8545179 A JP8545179 A JP 8545179A JP S568961 A JPS568961 A JP S568961A
Authority
JP
Japan
Prior art keywords
circuit
shading
input
white
video 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.)
Pending
Application number
JP8545179A
Other languages
Japanese (ja)
Inventor
Takashi Ogawa
Koji Ishikawa
Harumitsu Shimizu
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.)
NEC Corp
Nippon Telegraph and Telephone Corp
Original Assignee
NEC Corp
Nippon Telegraph and Telephone Corp
Nippon Electric Co 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 NEC Corp, Nippon Telegraph and Telephone Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP8545179A priority Critical patent/JPS568961A/en
Publication of JPS568961A publication Critical patent/JPS568961A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • H04N1/403—Discrimination between the two tones in the picture signal of a two-tone original

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Image Signal Circuits (AREA)

Abstract

PURPOSE:To eliminate bad influences of the shading of an optical system by using a shading correcting circuit for a facsimile equipment that converts video signals into black-and-white binary signals and sends them. CONSTITUTION:Video signals output from an image sensor are input to terminal 5. White-level extracting circuit 6 is an integral network which is charged with a time constant fast enough to follow up a maximum picture frequency and discharged with a slow time constant corresponding to the gradient of shading and from the input video signal, a white level is extracted. The output of circuit 6 is input to white-level drop stopping circuit 7 composed of a clamping circuit. Since this circuit 7 prevents accurate shading extraction from becoming impossible when the black interval of the video signal is extremely long, the input is clamped at a fixed potential equivalent to the minimum amplitude of shading. The output of circuit 7 is voltage-divided by variable resistor 9 and input as the reference potential of binary-coding circuit 11 and this reference potential and video signal 5 are compared to each other to obtain black-and-white binary signal 12 by converting.
JP8545179A 1979-07-05 1979-07-05 Shading correcting circuit Pending JPS568961A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP8545179A JPS568961A (en) 1979-07-05 1979-07-05 Shading correcting circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8545179A JPS568961A (en) 1979-07-05 1979-07-05 Shading correcting circuit

Publications (1)

Publication Number Publication Date
JPS568961A true JPS568961A (en) 1981-01-29

Family

ID=13859239

Family Applications (1)

Application Number Title Priority Date Filing Date
JP8545179A Pending JPS568961A (en) 1979-07-05 1979-07-05 Shading correcting circuit

Country Status (1)

Country Link
JP (1) JPS568961A (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52120613A (en) * 1976-04-02 1977-10-11 Olympus Optical Co Ltd Video signal processing circuit
JPS5315711A (en) * 1976-07-28 1978-02-14 Ricoh Co Ltd Picture signal processing circuit

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52120613A (en) * 1976-04-02 1977-10-11 Olympus Optical Co Ltd Video signal processing circuit
JPS5315711A (en) * 1976-07-28 1978-02-14 Ricoh Co Ltd Picture signal processing circuit

Similar Documents

Publication Publication Date Title
SU1099853A3 (en) Apparatus for reproducing originals
US2792496A (en) Stabilized direct current setting apparatus
JPS5675780A (en) Video signal processing circuit
ES461740A1 (en) Brightness control apparatus
JPS5529878A (en) Focus detector of camera
JPS568961A (en) Shading correcting circuit
JPS5534704A (en) Threshold setting circuit
GB2157106A (en) Gain control in a digital video signal processor
GB1518177A (en) Method and device for producing binary signals from an original by means of a television camera
JPS5560826A (en) Photometry
JPS6437178A (en) Digital video camera
JPS56102180A (en) Picture signal encoding system
US2521146A (en) Automatic blanking-level control for television receivers
US2871369A (en) Pulse amplitude equalizing system
JPS6156673B2 (en)
JPS54104265A (en) Gain control circuit
SU1148127A2 (en) Device for introducing symbol information in colour television signal
GB9023305D0 (en) Video signal processing
JPS55163941A (en) Television facsimile receiver
JPS5725076A (en) Method for binary-coding of video signal
JP2675079B2 (en) Binarization processing circuit
GB1397359A (en) Television apparatus
KR950003030B1 (en) Clamping circuit
JPS6441377A (en) Area identification method for picture processing unit
JPS55163962A (en) Driving method for solid-state pickup unit