JP3121056B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus such as a video camera, and more particularly to an image pickup apparatus having a function of properly correcting color balance when a light source for illuminating a subject is a fluorescent light. .

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing the configuration of a conventional image pickup apparatus having a color balance correction function. In the figure,
Reference numeral 11 denotes an image sensor including a solid-state image sensor, and reference numeral 12 denotes three primary colors R (red) output from the image sensor 11.
In a preamplifier circuit for amplifying a signal, a G (green) signal and a B (blue) signal, the gain of the R and B signal amplifiers can be adjusted for white balance control. Reference numeral 13 denotes a process circuit for performing a setup level adjustment, a blanking process, etc., from which a luminance signal Y and color difference signals RY, BY are obtained.
Is output. Reference numeral 14 denotes a color difference amplifier circuit for amplifying the color difference signals RY and BY, and each of the amplifiers is adjustable in gain. 15 is the luminance signal Y and the color difference signal R-
An encoder to which Y and BY are input, from which a composite video signal is output. Reference numeral 16 denotes a color temperature detecting means for detecting the color temperature of the light from the light source irradiating the subject, and 17 a system controller for controlling the preamplifier circuit 12 and the color difference amplifier circuit 14 based on the detected information.

[0003] In the image pickup apparatus constructed as described above, when photographing is started, first, the color temperature detecting means 16 operates to transmit the color temperature information of the light source to the system controller 17. The system controller 17 controls the preamplifier circuit 1 at the subsequent stage of the image sensor 11 according to the color temperature information.
The white balance is adjusted by changing the gain of the amplifiers of the R signal and B signal channels. At this time, the color temperature detecting means 16 is generally constituted by a light diffusing plate, R, G, and B optical sensors and an arithmetic circuit, and usually includes R / G and B / G.
Is input to the system controller 17 as the color temperature information.

An image signal captured by the image sensor 11 is output as R, G, and B color signals, and the white balance is adjusted by a preamplifier circuit 12, and then enters a process circuit 13, where blanking is performed. Processing and the like are performed and output as a luminance signal Y and color difference signals RY and BY. These signals are input to the encoder 15, where they are output as a composite video signal. The color difference signals RY and BY are amplified by the color difference amplifier circuit 14 and then input to the encoder 15. Is done. That is, the gain of the color difference signals RY and BY is controlled in accordance with the above-mentioned color temperature information. When the color temperature is low, the gain is increased to increase the saturation.
Thereby, the color balance is corrected by the difference in the color rendering of the light source, and the deterioration of the color reproducibility is prevented.

[0005]

However, in the above-described conventional imaging apparatus, the color balance due to the difference in the color rendering properties of the light source is corrected only by the color temperature information of the light source. Some light sources have high color rendering even at low color temperatures, and some light sources have low color rendering even at high color temperatures.Therefore, it may not be possible to correct the color balance properly. A light source having a high temperature and a low color rendering property has a problem in that the saturation is reduced and color reproducibility when the light source is a fluorescent lamp cannot be compensated.

The present invention has been made in view of the above-mentioned problems, and it is possible to correct an appropriate color balance even when a light source is a fluorescent light, and to achieve effective color reproducibility with a simple circuit configuration. It is an object of the present invention to obtain an imaging device capable of compensating for the above.

[0007]

An image pickup apparatus according to the present invention photoelectrically converts image pickup light from a subject and outputs an R (red) signal and a B signal.
(Blue) and an image sensor for generating a signal and G (green) signal, an optical occupied by from the fluorescent lamp light source for irradiating the pre-Symbol subject
A fluorescent lamp discriminating means for discriminating Mel ratio, the image cell
Of the R (red) and B (blue) signals output from the
Each of them was determined by the fluorescent lamp determining means.
Occupied by light from a fluorescent lamp as a light source for irradiating the subject light
By multiplying the coefficient corresponding to the ratio by the G (green) signal,
Subtracting means for subtracting the signal obtained by
G provided at the subsequent stage and output from the image sensor
(Green) signal and R (red) output from the subtraction means
A luminance signal and a color signal based on the signal and the B (blue) signal.
Process means for generating a difference signal .

[0008]

[0009]

FIG. 1 is a block diagram showing the configuration of an image pickup apparatus according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an image sensor that photoelectrically converts imaging light from a subject and outputs R, G, and B color signals, and is configured by a solid-state imaging device. Reference numeral 2 denotes a matrix circuit for performing a matrix operation on the color signal from the image sensor 1, and includes a subtractor 2a to which an R signal is input, a multiplier 2b to which a G signal is input, and a subtractor 2c to which a B signal is input. Have been. Reference numeral 3 denotes a preamplifier circuit for adjusting the white balance, which includes amplifiers 3a, 3b, and 3c for amplifying each color signal. The amplifiers 3a and 3c for the R signal and the B signal have variable gain adjustment for white balance control. . 4 performs blanking processing and the like,
From the G and B color signals, the luminance signal Y and the color difference signals RY, B-
A process circuit 5 for generating Y is an encoder for synthesizing the luminance signal Y output from the process circuit 4 and the color difference signals RY and BY, from which a composite video signal is output to the outside.

Reference numeral 6 denotes color temperature detecting means for detecting the color temperature of a light source for irradiating a subject, 7 denotes fluorescent light determining means for determining whether the light source is a fluorescent light, and 8 denotes the matrix circuit 2.
And a system controller that controls the entire system including the preamplifier circuit 3, controls the gains of the amplifiers 3 a and 3 c of the preamplifier circuit 3 based on the detection information of the color temperature detection means 6, A control circuit for controlling the addition ratio of the R and B color signals in the arithmetic processing by the subtracters 2a and 2c in the matrix circuit 2 is configured based on this.

Next, the operation will be described. As before,
The color temperature information of the light source detected by the color temperature detecting means 6 is converted into R / G and B / G signals by the system controller 8.
The system controller 8 controls the gains of the amplifiers 3a and 3c of the preamplifier circuit 3 according to the signal, and adjusts the white balance. In addition, the light source determination information determined by the fluorescent lamp determination means 7 is also input to the system controller 8, and the system controller 8 changes the addition ratio of the matrix circuit 2 based on the determination information. At that time, the system controller 8 changes the above-mentioned addition ratio of the matrix circuit 2 according to the degree of the discrimination, and appropriately corrects the color balance.

Here, in the matrix circuit 2, R '= R-αG, G' = G, B '= B-αG
Is performed. That is, the system controller 8
Controls the addition ratio of the color signals in each of the subtractors 2a and 2c by changing the value of a gain coefficient (gain control signal) α given to the multiplier 2b of the matrix circuit 2.
Correct the color balance. Then, the color signal whose color balance has been corrected is input to the preamplifier circuit 3, where the above-mentioned white balance is adjusted, and then enters the process circuit 4, where the luminance signal Y and the color difference signals RY and BY are output. And output as a video signal via the encoder 5.

FIG. 2 is a diagram showing the relationship between the degree (%) of the fluorescent lamp discrimination by the above-mentioned fluorescent lamp discriminating means 7 and the gain coefficient α to the matrix circuit 2. The gain coefficient α is set to, for example, 0.1 to 0.3, and when the degree of discrimination of the fluorescent lamp is large, that is, when the ratio of the light from the fluorescent lamp in the luminous flux illuminating the subject is large, the gain coefficient α Control is performed so that the gain coefficient increases. As described above, even when the light source includes a fluorescent lamp, appropriate color balance can be corrected, and effective color reproducibility can be compensated with a simple circuit configuration.

Incidentally, as the fluorescent lamp discriminating means 7, a so-called flicker detecting circuit or the like can be applied. In the above-described embodiment, the case where a pure color (three primary colors) color filter is used has been described. However, the present invention can be applied to a case where a complementary color filter is used.

[0015]

As is evident from the foregoing description, according to the present invention, the light source
Fluorescent lamp discriminating means for discriminating the ratio of light occupied by the fluorescent lamp is provided, and a luminance signal and a color difference
Since the signal is generated, an appropriate color balance can be corrected even when the light source is a fluorescent lamp, and there is an effect that effective color reproducibility can be compensated with a simple circuit configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a degree of discrimination of a fluorescent lamp and a gain coefficient to a matrix circuit.

FIG. 3 is a block diagram showing a configuration of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image sensor 2 Matrix circuit 3 Preamplifier circuit 4 Process circuit 5 Encoder 6 Color temperature detecting means 7 Fluorescent lamp discriminating means 8 System controller (control circuit)

Claims (1)

(57) [Claims] 1. An imaging light from a subject is photoelectrically converted to R
(Red) signal, B (blue) signal and G (green) signal
An image sensor for forming, split occupied by light from the fluorescent lamp light source for irradiating the pre-Symbol subject
A fluorescent lamp determining means for determining a match ; an R (red) signal output from the image sensor;
From each of the B (blue) signals,
The fluorescent light of the light source for irradiating the subject light
Multiply the coefficient according to the ratio of the light and the G (green) signal.
Subtracting means for subtracting the signal obtained by the subtraction ,
(Green) signal output from the above and the output from the subtraction means
Based on the obtained R (red) signal and B (blue) signal.
Process means for generating a degree signal and a color difference signal.
Imaging device, characterized in that that.