GB2129635B - Controlling the grey levels represented by a video signal - Google Patents

Controlling the grey levels represented by a video signal

Info

Publication number
GB2129635B
GB2129635B GB8027931A GB8027931A GB2129635B GB 2129635 B GB2129635 B GB 2129635B GB 8027931 A GB8027931 A GB 8027931A GB 8027931 A GB8027931 A GB 8027931A GB 2129635 B GB2129635 B GB 2129635B
Authority
GB
United Kingdom
Prior art keywords
circuit
pixels
mean
grey level
dispersion
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
GB8027931A
Other versions
GB2129635A (en
Inventor
Philip Valentine Coates
Brian John Eaton
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.)
EMI Ltd
Original Assignee
EMI 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 EMI Ltd filed Critical EMI Ltd
Priority to GB8027931A priority Critical patent/GB2129635B/en
Publication of GB2129635A publication Critical patent/GB2129635A/en
Application granted granted Critical
Publication of GB2129635B publication Critical patent/GB2129635B/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/30—Transforming light or analogous information into electric information
    • H04N5/33—Transforming infrared radiation

Abstract

A digital buffer store 25 stores digitised samples of a video signal. A circuit 206 determines the mean grey level (f(b)) of the stored signals and a circuit 28 forms a histogram indicating the number of pixels having various ones of 8 possible grey levels. Circuit 29 determines the dispersion of the histogram about the mean grey level. In principle, circuit 29 could determine from the mean level and the histogram the statistical distribution of pixels amongst the grey levels and from that determine the standard deviation as a measure of dispersion. In practice, the circuit 29 determines an empirical approximation to the dispersion, <IMAGE> where n = number of binary bits = 3 Ni = number of pixels having a grey level i A = f(b) = mean grey level NA = number of pixels having the mean grey level. This equation is advantageous as it operates on powers of 2. The determined values of f(a) and f(b) are compared with empirically derived desired values and servo the gain and D.C. Offset applied to the video signals in a circuit 20. <IMAGE>
GB8027931A 1979-09-21 1980-09-03 Controlling the grey levels represented by a video signal Expired GB2129635B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8027931A GB2129635B (en) 1979-09-21 1980-09-03 Controlling the grey levels represented by a video signal

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7932777 1979-09-21
GB8027931A GB2129635B (en) 1979-09-21 1980-09-03 Controlling the grey levels represented by a video signal

Publications (2)

Publication Number Publication Date
GB2129635A GB2129635A (en) 1984-05-16
GB2129635B true GB2129635B (en) 1984-12-19

Family

ID=26272965

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8027931A Expired GB2129635B (en) 1979-09-21 1980-09-03 Controlling the grey levels represented by a video signal

Country Status (1)

Country Link
GB (1) GB2129635B (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2565447B1 (en) * 1984-06-05 1987-08-21 Software Based Systems Sbs DEVICE FOR DIGITIZING A VIDEO IMAGE AND SYSTEM FOR DIGITIZING AND VIEWING AN IMAGE
FR2581775B1 (en) * 1985-05-10 1990-03-23 Thomson Cgr METHOD FOR ADJUSTING THE GRAY SCALE IN THE REPRODUCTION OF DIGITAL IMAGES AND SYSTEM IMPLEMENTING THIS METHOD
GB8521019D0 (en) * 1985-08-22 1986-10-01 Rank Pullin Controls Ltd Imaging apparatus
FR2595153B1 (en) * 1986-02-28 1990-12-07 Thomson Cgr DIGITAL IMAGING SYSTEM WITH GRAY SCALE ADJUSTMENT, PARTICULARLY FOR VIEWING BLOOD VESSELS
FR2633746A1 (en) * 1988-07-01 1990-01-05 Labo Electronique Physique DIGITAL IMAGE MODIFICATION METHOD AND SYSTEM FOR IMPLEMENTING THE SAME
JPH087785B2 (en) * 1989-05-16 1996-01-29 松下電器産業株式会社 Binarization processor
FR2669800A1 (en) * 1990-11-23 1992-05-29 Thomson Trt Defense AUTOMATIC DEVICE FOR ADJUSTING THE BRIGHTNESS OF IMAGES FROM A CAMERA AND CAMERA COMPRISING SUCH A DEVICE.
FR2669801B1 (en) * 1990-11-23 1997-01-31 Thomson Trt Defense AUTOMATIC DEVICE FOR ADJUSTING THE CONTRAST OF IMAGES FROM A CAMERA AND CAMERA COMPRISING SUCH A DEVICE.
JP3556138B2 (en) * 1998-12-24 2004-08-18 富士通株式会社 Display device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2046051B (en) * 1979-03-29 1983-01-26 Philips Electronic Associated Real time histogram modification system for image processing

Also Published As

Publication number Publication date
GB2129635A (en) 1984-05-16

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19940903