EP0221539A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
White balance correction circuit
Assignee: Sanyo Electric Co Ltd
•
Filing: 1986-11-04
•
Granted: —
•
Expires: 2006-11-04
Abstract
Abstract A correction signal switching circuit (8) is switched in response to an illuminance discrimination output from an illuminance detecting circuit (9). Namely, the correction signal switching circuit (8) supplies the output from a first white balance correction signal generator 1 to a color signal level correction circuit (5) when an object is under high illuminance while supplying the output of a second white balance correction signal generator (2) to the color signal level correction circuit (5) when the object is under low illuminance. As the result, white balance can be corrected in an appropriate system in response to the illuminance.
Inventors
- 👤 Mitsuo Seki
- 👤 Keiichi Tanii
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 21:55
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/80; H04N23/84; H04N23/88
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
191 words
A white balance correction circuit for correcting white balance of color signals obtained by acquisiting the image of an object, said white balance correction circuit comprising: first white balance correction means (1, 5, 10) for detecting the color temperature of said object by employing a photodetector device (la) arranged to face said object and generating first white balance correction signals correlating to said detected color temperature of said object thereby to correct levels of said color signals on the basis of said first white balance correction signals; second white balance correction means (2, 5, 11, 20) for generating second white balance correction signals correlating to average levels of color difference signals formed by said color signals thereby to correct levels of said color signals on the basis of said second white balance correction signals; image pickup state detecting means (9, 13, 14) for detecting the image pickup state of said object; and operating state switching means (8, 12, 15) for switching operating states of said first white balance correction means and said second white balance correction means in response to the result of detection by said image pickup state detecting means.
Claim 2
Dependent Claim
191 words
A white balance correction circuit for correcting white balance of color signals obtained by acquisiting the image of an object, said white balance correction circuit comprising: first white balance correction means (1, 5, 10) for detecting the color temperature of said object by employing a photodetector device (la) arranged to face said object and generating first white balance correction signals correlating to said detected color temperature of said object thereby to correct levels of said color signals on the basis of said first white balance correction signals; second white balance correction means (2, 5, 11, 20) for generating second white balance correction signals correlating to average levels of color difference signals formed by said color signals thereby to correct levels of said color signals on the basis of said second white balance correction signals; image pickup state detecting means (9, 13, 14) for detecting the image pickup state of said object; and operating state switching means (8, 12, 15) for switching operating states of said first white balance correction means and said second white balance correction means in response to the result of detection by said image pickup state detecting means.
Claim 3
Dependent Claim
37 words
A white balance correction circuit in accordance with claim 1, wherein said image pickup state detecting means includes an illuminance discriminator circuit (9) for detecting the amount of light on said object to derive illuminance discrimination output.
Claim 4
Dependent Claim
35 words
A white balance correction circuit in accordance with claim 2, wherein said illuminance discriminator circuit detects said amount of light on said object on the basis of a blue signal obtained from said photodetector device.
Claim 5
Dependent Claim
89 words
A white balance correction circuit in accordance with claim 2, wherein said operating state switching means includes a correction signal switching circuit (8) for selectively switching said first white balance correction signals and said second white balance correction signals in response to said illuminance discrimination output, and said first and second white balance correction means commonly include a color signal level correction circuit (5) for correcting levels of said color signals in response to said first or second white balance correction signals supplied from said correction signal switching circuit.
Claim 6
Dependent Claim
71 words
A white balance correction circuit in accordance with claim 4, wherein said correction signal switching circuit supplies said first white balance correction signals to said color signal level correction circuit when said illuminance discriminator circuit derives an illuminance discrimination output indicating high illuminance while supplying said second white balance correction signals to said color signal level correction circuit when said illuminance discriminator circuit derives an illuminance discrimination output indicating low illuminance.
Claim 7
Dependent Claim
36 words
A white balance correction circuit in accordance with claim 1, wherein said image pickup state detecting means includes color determination means (13, 14) for determining whether or not imbalance of color is cased on said object.
Claim 8
Dependent Claim
42 words
A white balance correction circuit in accordance with claim 6, wherein said color determination means includes level difference determination means (13) for determining the value of level difference between said first white balance correction signals and said second white balance correction signals.
Claim 9
Dependent Claim
60 words
A white balance correction circuit in accordance with claim 7, wherein said operating state switching means includes color signal switching means (12) for selectively switching color signals corrected by said first white balance correction means and color signals corrected by said second white balance correction means and deriving the same in response to output from said level difference determination means.
Claim 10
Dependent Claim
89 words
A white balance correction circuit in accordance with claim 8, wherein said color signal switching means selects said color signals corrected by said first white balance correction means when said level difference determination means determines that said level difference between said first white balance correction signals and said second white balance correction signals is larger than a prescribed value while selecting said color signals corrected by said second white balance correction means when said level difference determination means determines that said level difference is smaller than said prescribed value.
Claim 11
Dependent Claim
80 words
A white balance correction circuit in accordance with claim 6, wherein said second white balance correction means is adapted to recorrect color signals corrected by said first white balance correction means, and said color determination means includes level determination means (14) for determining whether or not at least one of respective average levels of two color difference signals produced on the basis of color signals corrected by said first white balance correction means comes out of a prescribed level range.
Claim 12
Dependent Claim
58 words
A white balance correction circuit in accordance with claim 10, wherein said operating state switching means includes inhibiting means (15) for inhibiting correction operation of said second white balance correction means when said level determination means determines that at least one of respective average levels of said two color difference signals comes out of said prescribed level range.
Claim 13
Dependent Claim
45 words
A white balance correction circuit in accordance with claim 11, wherein said inhibiting means inhibits said correction operation of said second white balance correction means by inputting fixed signals in place of color difference signals to be inputted in said second white balance correction means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.