JPH04170888A - White balance correction device - Google Patents

Abstract

PURPOSE:To appropriately correct a white balance in spite of a distance between an image pickup device and a subject by controlling the white balance based on output information from the image pickup device, detection information of a color temperature detection means and measurement information of a distance-measuring means. CONSTITUTION:The color temperature detection means 6 detecting color temperature information on incident light from the subject, the distance-measuring means 12 measuring the distance between the color temperature detection means 6 and the subject and a white balance control circuit 13 controlling the white balance based on measurement information of the distance-measuring means 12 are provided. The white balance control circuit 13 changes the white balance by distance information from the distance-measuring sensor 12 and outputs it to amplifiers 3a and 3b for white balance control. Thus, the white balance can appropriately be corrected in spite of the distance to the subject.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a white balance correction device for an imaging device such as a video camera.

[Conventional technology]

Conventionally, devices for correcting the white balance of video cameras and the like have either controlled the white balance based on information obtained from the image sensor itself, or controlled the white balance based on the color temperature information of the incident light from the subject. There is something that controls it. There is also known a correction device that combines the two and controls white balance using information from both.

FIG. 4 is a block diagram showing a schematic configuration of a conventional white balance correction device that combines both information from the image sensor and color temperature information. In the figure, reference numeral 1 denotes a COD, which is a solid-state imaging device, in which imaging light from a subject is photoelectrically converted. 2 is R (red) from the output signal of CCD 1
, a color separation circuit that separates G (edge) and B (blue) color signals;
3a.

3b is a variable gain controllable white balance control amplifier (amplifier) that amplifies the R and B color signals output from the color separation circuit 2; 4 is a gain-controlled R and B color signal and color separation circuit 2; A luminance signal Y and a color difference signal RY are generated by manually inputting the G color signal from .

5 is a signal processing circuit that generates a standard television signal by inputting the luminance signal Y and color difference signals RY and B-Y; 6 is a color of incident light from the subject; A color temperature sensor detects temperature information, and 7 is a white balance control circuit that controls white balance based on the detection information of the color temperature sensor 6 and the output information from the CCD 1. Here, the color temperature information and the color difference signal R are The gains of the white balance control amplifiers 3a and 3b are controlled based on the information obtained by comparing -Y and BY with the reference level.

In the apparatus configured as described above, the imaging light from the subject that enters the CCD 1 is photoelectrically converted, and then
The signal is sent to a color separation circuit 2 and separated into color signals of the three primary colors R2O and B. Among these color signals, the R and B color signals are input to the signal processing circuit 4 via white balance control amplifiers 3a and 3b, and the G color signal is directly input to the signal processing circuit 4. The signal processing circuit 4 generates a luminance signal Y and color difference signals R-Y and B-Y, which are input to the signal processing circuit 5 at the subsequent stage.

On the other hand, the light from the subject also enters the color temperature sensor 6, where the color temperature information of the incident light is detected, and the color temperature information is input to the white balance control circuit 7. This white balance control circuit 7 also includes the signal processing circuit 4.
The color difference signals R-Y and B-Y are inputted. and,
The white balance control circuit 7 generates a control signal based on each manually inputted signal, and this control signal is supplied to the white balance control amplifiers 3a and 3b.

Thereby, the white balance is controlled to be optimal.

The luminance signal Y and the white balance-controlled color difference signals R-Y and B-Y are input to the signal processing circuit 5 as described above, where they are converted into standard television signals and then output to the outside. .

Next, the control operation of the above-mentioned white balance control circuit 7 will be explained in detail. , FIG. 5 is a diagram showing the internal configuration of the control circuit 7. As shown in FIG. In the figure, reference numeral 8 denotes a first gain control signal forming circuit that uniquely forms gain control signals (white balance correction signals) R1 and B1 for R and B signals according to color temperature information from the color temperature sensor 6. , 9 is the color difference signal R-
A second gain control signal forming circuit 10a, 10b compares Y, B-Y and its achromatic color level (■r6f) to form gain control signals R2, B2 of the R signal and B signal. Limiters 11a and llb limit the gain control signals R2 and B2 outputted from the gain control signal forming circuit 9 of the first gain control signal forming circuit 9. This is an arithmetic unit that adds R1 and B2 and outputs the result.

In the circuit shown in FIG. 5 above, the gain control signal forming circuit 8 of the cabinet 1
A limiter 10a is applied to the control signals R1 and Bl output from
, 10b, the second width is regulated to a predetermined limit width by
The control signals R2 and 82 from the gain control signal forming circuit 9 are added to the R correction signal and the B correction signal. This signal is then transmitted to the white balance control amplifier 3a in FIG.
3b as a control signal, and the white balance is optimally controlled. In this way, the gains of the white balance control amplifiers 3a and 3b are controlled based on both the output information from the CCD 1 and the detection information of the color temperature sensor 6 in FIG. 1, and the white balance is appropriately corrected. Ru.

[Problem to be solved by the invention]

However, with conventional white balance correction devices such as those mentioned above, the limiter's regulation range is fixed to a preset value, so when the subject is far away, the incident light of the color temperature sensor and the subject The color temperature of the light source that illuminates the image sensor may differ considerably, and in this case, the control signal according to the color temperature information cannot be fully corrected by the output signal from the image sensor, resulting in the problem that appropriate white balance correction cannot be performed. .

The present invention has been made with attention to such problems, and an object of the present invention is to provide a white balance correction device that can perform appropriate white balance correction regardless of the distance between an imaging device and a subject.

[Means to solve the problem]

The white balance correction device of the present invention is configured as follows.

In a white balance correction device for an imaging device equipped with an image sensor that photoelectrically converts imaging light from a subject, a color temperature detection means for detecting color temperature information of incident light from the subject, the color temperature detection means and the subject. and a white balance control circuit that controls white balance based on the output information from the image sensor, the detection information of the color temperature detection means, and the measurement information of the distance measurement means. Prepared.

(2) In the above-mentioned device, the white balance control circuit outputs a white balance control signal based on the output information from the image sensor and the detection information of the color temperature detection means, while changing the white balance control signal based on the measurement information of the distance measuring means. did.

Formerly, an image sensor that photoelectrically converts imaging light from a subject, a color separation circuit that separates multiple color signals from the output signal of this image sensor, and a gain control that controls the gain of a predetermined color signal among the color signals. A white balance correction device for an imaging device, comprising: a color temperature detection means for detecting color temperature information of incident light from a subject; and a distance measuring means for measuring a distance between the color temperature detection means and the subject. , a white balance control circuit that outputs a control signal for white balance correction to the gain control means, and the white balance control circuit includes a first control circuit that generates a gain control signal according to the detection information of the color temperature detection means. a second gain control signal forming circuit that forms a gain control signal from a result of comparing the level of the color signal from the image sensor with a reference level; and limiting means for limiting the output based on measurement information of the distance measuring means,
A control signal based on the output limited by the limiting means and the output of the first gain control signal forming circuit is output to the gain controlling means.

[Effect]

The white balance correction device of the present invention is provided with a distance measuring means for measuring the distance between the color temperature detecting means and the subject, and the measurement information of the distance measuring means, the output information from the image sensor, and the color temperature information are combined. The white balance is controlled based on this. Therefore, it is possible to prevent the white balance control signal from being unable to be fully corrected depending on the distance between the imaging device and the subject.

〔Example〕

FIG. 1 is a block diagram showing the circuit configuration of a white balance correction device according to an embodiment of the present invention, and the same reference numerals as in FIG. 4 indicate the same components. In the figure, 1 is a CCD (solid-state image sensor) that photoelectrically converts imaging light from a subject, and 2 is a color separation circuit that separates multiple color signals from the output signal of CCD 1. Specifically, R, G, and , B are separated and output. Reference numerals 3a and 3b denote white balance control amplifiers (gain control means) for controlling the gain of a predetermined color signal among the three primary color signals, and here variable gain control is performed for each of the R and B color signals. 4 is R and B output from these white balance control amplifiers 3a and 3b.
5 is a signal processing circuit which receives the color signal of G and the color signal of G outputted from the color separation circuit 2 and generates a luminance signal Y and color difference signals R-Y and B-Y; 5 indicates the luminance signal Y and color difference signal R;
A signal processing circuit that generates and outputs a standard television signal from -Y and B-Y, 6 a color temperature sensor (color temperature detection means) that detects color temperature information of incident light from a subject, 12 this color temperature A distance measurement sensor (distance measurement means) 13 that measures the distance between the sensor 6 and the subject performs white balance based on the output information from the CCD 1, the detection information of the color temperature sensor 6, and the measurement information of the distance measurement sensor 12. The white balance control circuit that controls the color difference signal RY generated by the signal processing circuit 4 as output information from the CCD 1,
B-Y is input, white balance control amplifier 3a
, 3b output a control signal for white balance correction.

FIG. 2 is a diagram showing the internal configuration of the white balance control circuit 13, and the same reference numerals as in FIG. 5 indicate the same components. In the figure, 8 is a first gain control signal forming circuit that forms gain control signals (white balance correction signals) R1 and Bl according to the detection information (color temperature information) of the color temperature sensor 6, and 9 is a first gain control signal forming circuit that forms gain control signals (signals for white balance correction) R1 and Bl according to the detection information (color temperature information) of the color temperature sensor 6. Gain control signals R2, B are obtained from the result of comparing the level of the color signal (here, the level of the color difference signals R-Y, B-Y) with the reference achromatic color level (vref).
1. A second gain control signal forming circuit forming 2, 14a, 1
4b is a limiter that limits the output of the second gain control signal forming circuit 9 based on the output information of the limit width variable means 15, and the limit width variable means 15 is supplied with measurement information (distance information) from the distance measuring sensor 12. Ru. Then, an R correction signal and a B correction signal obtained by adding the output limited by the limiters 14a and 14b and the output of the first gain control signal forming circuit 8 in the arithmetic units 11a and llb are used as control signals for the white balance control amplifier. 3a and 3b.

Next, the operation will be explained.

The signal processing operation from when the imaging light from the subject is incident on the CCD 1 until the standard television signal is output from the signal processing circuit 5 is the same as that of the apparatus shown in FIG. is provided with a distance sensor 12 that measures the distance between the color temperature sensor 6 and the subject, and white balance control is performed in consideration of the distance information measured by the distance sensor 12. That is, the white balance control circuit 13 changes the white balance control signal based on the output information from the CCD 1 and the color temperature information from the color temperature sensor 6 according to the distance information from the distance measuring sensor 12 to perform white balance control. amplifier 3a
, 3b. Therefore, the white balance control signal will not be unable to be corrected completely depending on the distance between the imaging device and the subject, and appropriate white balance correction can be performed regardless of the distance to the subject.

Figure 3 shows the distance to the subject and the limiter 14a in Figure 2,
14b shows the relationship with the limit width. The limiters 14a and 14b operate according to the characteristics shown in FIG. 3, and the longer the distance between the imaging device such as a camera and the object, the more the color temperature of the incident light of the color temperature sensor 6 and the light source that illuminates the object changes. This is based on the prediction that the probability that the values will differ will be higher. Therefore, in addition to the characteristics shown in FIG. 3, characteristics that take into account the case where the imaging device and the subject are very close may also be used, and the directivity of the color temperature sensor 6,
When a zoom lens is used, the characteristics may be determined by taking into account its zoom ratio and the like.

Note that the distance sensor 12 that measures the distance to the subject is
It may be of any type, for example, a known automatic focusing device.

[Effects of the Invention] As described above, according to the present invention, a distance measuring means for measuring the distance to a subject is provided, and a distance measuring means is provided to measure the distance to the subject, and the distance measuring means is used to measure the distance to the subject based on the measurement information of the distance measuring means, the output information of the image sensor, and the color temperature information. Since the white balance is controlled by using the image pickup device, there is an effect that appropriate white balance correction can be performed regardless of the distance between the imaging device and the subject.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of a white balance correction device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the internal configuration of the white balance control circuit of FIG. 1, and FIG.
The figure is a characteristic diagram showing the relationship between the distance to the subject and the limit width of the limiter in Figure 3, Figure 4 is a block diagram showing the circuit configuration of the conventional device, and Figure 5 is the white balance control circuit of Figure 4. FIG. 3 is a configuration diagram showing the internal configuration. 1-----CCD (solid-state image sensor) 2--color separation circuit 4.5--signal processing circuit 6--color temperature sensor (color temperature detection means) 8--
...First gain control signal forming means 9-:----Second
Gain control signal forming means 11a, 11b---
-- Arithmetic unit 12 -- Distance sensor (distance measuring means) 13 -- White balance control circuit 14 a,
14 b---Limiter (limiting means) 15------
-Limit width variable means

Claims (3)

[Claims] (1) In a white balance correction device for an imaging device equipped with an image sensor that photoelectrically converts imaging light from a subject, a color temperature detection means for detecting color temperature information of incident light from the subject; A distance measuring means for measuring the distance between objects, and a white balance control circuit for controlling white balance based on output information from the image sensor, detection information from the color temperature detecting means, and measurement information from the distance measuring means. A white balance correction device characterized by: (2) The white balance control circuit is characterized in that the white balance control circuit outputs a white balance control signal based on the output information from the image sensor and the detection information of the color temperature detection means, while changing the white balance control signal based on the measurement information of the distance measurement means. The white balance correction device according to item 1. (3) an image sensor that photoelectrically converts imaging light from a subject;
In a white balance correction device for an imaging device, which includes a color separation circuit that separates a plurality of color signals from the output signal of the imaging device, and a gain control means that controls the gain of a predetermined color signal among the color signals, a color temperature detection means for detecting color temperature information of incident light from a subject; a distance measurement means for measuring a distance between the color temperature detection means and a subject; and outputting a control signal for white balance correction to the gain control means. a first gain control signal forming circuit that forms a gain control signal according to detection information of the color temperature detection means;
a second gain control signal forming circuit that forms a gain control signal from the result of comparing the level of the color signal from the image sensor with a reference level; and an output of the second gain control signal forming circuit that is measured by the distance measuring means. and a limiting means for limiting based on information, and outputting a control signal based on the output limited by the limiting means and the output of the first gain control signal forming circuit to the gain controlling means. Balance correction device.