EP0530793A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
White balance control circuit in an image pickup apparatus
Assignee: Canon Inc
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Filing: 1992-09-03
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Granted: —
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Expires: 2012-09-03
Abstract
Abstract In controlling the gain of plural color signals, for the purpose controlling the white balance of a video signal released from an image pickup device and including the above-mentioned plural color signals, there is provided a calculation circuit for calculating color temperature information according to the plural color signals and forming a gain control signal according to the color temperature information, and the variable range of the gain control signal is set at one of mutually non-overlapping plural ranges, whereby the correction error of the white balance is rendered visually inconspicuous. Also in the calculation circuit, the plural color information are weighted according to the result of multiplication of plural coefficients which are variably set according to the mutually different plural hue components of the video signal, and the gain control signal is calculated according to thus weighted plural color information, whereby the white balance is stably controlled despite of the movement of object, variation in image frame or variation in color temperature.
Inventors
- 👤 Hirofumi C/O Canon Kabushiki Kaisha Takei
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:18
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/80; H04N23/84; H04N23/88
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
106 words
An image pickup apparatus comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color signals; b) gain control means for receiving a gain control signal and controlling the gain of said plural color signals according to said gain control signal; and c) calculation means for calculating color temperature information relative to color temperature, according to said plural color signals, and forming said gain control signal according to said color temperature information, wherein said calculation means includes range setting means for setting the variable range of said gain control signal at one of mutually non-overlapping plural ranges.
Claim 2
Dependent Claim
57 words
An apparatus according to claim 1, further comprising: luminance detection means for generating luminance information relative to the luminance of said object; wherein said range setting means is adapted to select one of said plural ranges according to said luminance information, and said calculation means is adapted to limit said gain control signal within said selected range.
Claim 3
Dependent Claim
43 words
An apparatus according to claim 2, further comprising: an iris for limiting the light coming from the object and entering said image pickup means; wherein said luminance detection means is adapted to generate said luminance information by detecting the state of said iris.
Claim 4
Dependent Claim
22 words
An apparatus according to claim 2, wherein said luminance detection means includes a luminance sensor for detecting the luminance of external light.
Claim 5
Dependent Claim
122 words
An image pickup apparatus comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color signals; b) an iris for limiting the light coming from the object and entering said image pickup means; c) gain control means for receiving a gain control signal and controlling the gain of said plural color signals according to said gain control signal; and d) calculation means for calculating color temperature information relative to color temperature according to said plural color signals, and forming said gain control signal according to said color temperature information; wherein said calculation means includes limiting means for limiting the variable range of said gain control signal, according to the state of said iris.
Claim 6
Dependent Claim
28 words
An apparatus according to claim 5, wherein said limiting means is adapted to set the variable range of said calculation means at one of mutually different plural ranges.
Claim 7
Dependent Claim
128 words
An image pickup apparatus, comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color signals; b) luminance detection means for generating luminance information relative to the luminance of said object; c) gain control means for receiving a gain control signal, and controlling the gain of said plural color signals according to said gain control signal; and d) calculation means for calculating color temperature information relative to color temperature according to said plural color signals, and forming said gain control signal according to said color temperature information; wherein said calculation means includes limiting means for limiting the variable range of the result of calculation on data relating to said gain control signal and data relating to said luminance information.
Claim 8
Dependent Claim
23 words
An apparatus according to claim 7, wherein said limiting means is adapted also to limit the variable range of said gain control signal.
Claim 9
Dependent Claim
29 words
An apparatus according to claim 7, wherein said limiting means is adapted to set the variable range of said result of calculation at one of mutually different plural ranges.
Claim 10
Dependent Claim
14 words
An apparatus according to claim 9, wherein said plural ranges do not mutually overlap.
Claim 11
Dependent Claim
30 words
An apparatus according to claim 9, wherein said limiting means is adapted also to set the variable range of said gain control signal at one of mutually different plural ranges.
Claim 12
Dependent Claim
141 words
An image pickup apparatus, comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color signals; b) gain control means for receiving a gain control signal and controlling the gain of said plural color signals according to said gain control signal; and c) calculation means for calculating color temperature information relative to color temperature according to said plural color signals, and forming said gain control signal according to said color temperature information; wherein said calculation means includes range setting means for setting the variable range of said gain control signal at one of mutually different plural ranges, and said range setting means is adapted to set the variable range of said gain control signal at the widest one of said plural ranges, prior to the start of function of said calculation means.
Claim 13
Dependent Claim
57 words
An apparatus according to claim 1, further comprising: luminance detection means for generating luminance information relative to the luminance of said object; wherein said range setting means is adapted to select one of said plural ranges according to said luminance information, and said calculation means is adapted to limit said gain control signal within said selected range.
Claim 14
Dependent Claim
127 words
An image pickup apparatus, comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color signals; b) gain control means for receiving a gain control signal and controlling the gain of said plural color signals according to said gain control signal; and c) calculation means for forming said gain control signal according to plural color information relative to said plural color signals; wherein said calculation means includes weighting means for weighting said plural color information with a coefficient that is determined according to the values of said plural color signals and that can assume at least three values, and is adapted to calculate said gain control signal according to said plural color information weighted by said weighting means.
Claim 15
Dependent Claim
26 words
An apparatus according to claim 14, wherein said weighting means is adapted to continuously vary said coefficient according to the values of said plural color signals.
Claim 16
Dependent Claim
33 words
An apparatus according to claim 14, wherein said video signal further includes a luminance signal, and said weighting means is adpated to vary said weighting according to the value of said luminance signal.
Claim 17
Dependent Claim
49 words
An apparatus according to claim 14, further comprising: luminance detection means for generating luminance information relative to the luminance of said object; wherein said weighting means includes varying means for varying the relation between the values of said plural color signals and said coefficient, according to said luminance information.
Claim 18
Dependent Claim
33 words
An apparatus according to claim 17, wherein said varying means is adapted to continuously vary the relation between the values of said plural color signals and said coefficient, according to said luminance information.
Claim 19
Dependent Claim
43 words
An apparatus according to claim 17, further comprising: an iris for limiting the light coming from the object and entering said image pickup means; wherein said luminance detection means is adapted to generate said luminance information by detecting the state of said iris.
Claim 20
Dependent Claim
122 words
An image pickup apparatus comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color singals; b) gain control means for receiving a gain control signal and controlling the gain of said plural color signals according to said gain control signal; and c) calculation means for forming said gain control signal according to plural color information relative to said plural color signals; wherein said calculation means includes weighting said plural color information according to the result of multiplication of plural coefficients determined according to mutually different plural hue components of said video signal, and is adapted to calculate said gain control signal according to said plural color information weighted by said weighting means.
Claim 21
Dependent Claim
24 words
An apparatus according to claim 20, wherein said weighting means is adapted to continuously vary said plural coefficients according to said plural hue components.
Claim 22
Dependent Claim
55 words
An apparatus according to claim 20, wherein said video signal further includes a luminance signal, and said weighting means is adapted to vary said weighting according to the result of multiplication of all of a coefficient determined according to the value of said luminance signal and plural coefficients determined according to said plural hue components.
Claim 23
Dependent Claim
46 words
An apparatus according to claim 20, further comprising: luminance detection means for generating luminance information relative to the luminance of said object; wherein said weighting means includes varying means for varying the relation between said plural hue components and said coefficient according to said luminance information.
Claim 24
Dependent Claim
157 words
An image pickup apparatus, comprising: a) image pickup means for forming, from the light coming from an object, a video signal including plural color signals; b) luminance detection means for generating luminance information relative to the luminance of said object; c) gain control means for receiving a gain control signal and controlling the gain of said plural color signals according to said gain control signal; and d) calculation means for forming said gain control signal according to plural color information relative to said plural color signals; wherein said calculation means includes weighting means for weighting said plural color information with a coefficient determined according to the values of said plural color signals, and is adapted to calculate said gain control signal according to said plural color information weighted by said weighting means; and wherein said weighting means includes varying means for varying the relation between said plural color signals and said coefficient, according to said luminance information.
Claim 25
Dependent Claim
27 words
An apparatus according to claim 24, wherein said varying means is adapted to cotinuously vary the relation between said plural color signals according to said luminance information.
Claim 26
Dependent Claim
43 words
An apparatus according to claim 24, further comprising: an iris for limiting the light coming from said object and entering said image pickup means; wherein said luminance detection means is adapted to generate said luminance information by detecting the state of said iris.
References Cited (Backward Citations)
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