JP2002281512A - Device and method for controlling white balance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform optimal white balance output in a high color temperature environment such as the shade or the sky in outdoor photographing. SOLUTION: This device is provided with a color temperature detecting part 4 for detecting the color temperature of an object, arithmetic part 4 for calculating a target white balance value, brightness information detecting part 32 for detecting brightness information showing the brightness of the object, deciding part 4 for deciding whether brightness is higher than a prescribed threshold or not, and control part 4 for controlling the output gains of R, G and B signals so that white balancing can be performed at a color temperature lower tan the target white balance value when brightness is decided higher than the prescribed threshold and the color temperature of the object becomes higher than a first color temperature and lower than a second color temperature, and controlling the output gains of the R, G and B signals so that the white balance can follow the target white balance value with the elevation of the color temperature of the object to the second color temperature when the color temperature of the object becomes higher than the first color temperature and lower than the second color temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a white balance control device and a white balance control method for automatically performing white balance in a video camera, a digital still camera, and the like.

[0002]

2. Description of the Related Art White balance is a light source (subject).
When the color temperature changes, the white color moves along the blackbody radiation curve (blackbody locus) shown in FIG. 5 according to the change in the color temperature, and the color appears white (for example, in the case of a low color temperature). Is reddish and bluish at high color temperatures) to achromatic white. Here, the color temperature refers to the absolute temperature of a black body having the same chromaticity as the test light source.

[0003] By the way, CCD (Charge-Coupled Device)
e) In a video camera or digital still camera using a solid-state image sensor as an imaging device, the color temperature of the light source changes due to the change in the color temperature of the light source in order to project the white color of the subject as an achromatic white color from the imaging result. An automatic white balance processing function is provided to adjust the white that appears to be colored to achromatic white by moving white along the blackbody radiation curve accordingly. Actually, CCD (Charge
-Coupled Device) three primary colors (R,
A method of electronically amplifying and attenuating the signal intensities of G and B) to change the signal balance of each color to correct the color temperature of the image and adjust the white balance.

[0004]

However, as described above, a digital camera using the method of electronically correcting the color temperature of an image by changing the signal balance of each color or a digital still camera is used for outdoor photography. In this case, the color temperature of the sky and the color temperature of the shade cannot be distinguished because they both indicate a high color temperature, which causes the following problem.

For example, if an optimal white balance output is set in the shade, when a subject containing a lot of sky is photographed, the natural blue inherent in the sky becomes whitish due to the white balance. On the other hand, if the setting is such that the optimum white balance output can be obtained in order to express the natural blueness of the sky, there is a problem that the shade becomes too blue in the shade.

Accordingly, the present invention has been devised to solve the above-described problem. In outdoor photography, it is possible to output an optimal white balance in a high color temperature environment such as a shade or sky. It is an object to provide a white balance control device and a white balance control method.

[0007]

In order to achieve the above object, a white balance control device according to the present invention calculates a white balance from an R signal, a G signal, and a B signal obtained when an outdoor subject is imaged. A color temperature detecting means for detecting a color temperature of the subject as a reference for matching; and a white balance target value which is a target value for white balance adjustment based on the color temperature detected by the color temperature detecting means. Calculating means, brightness information detecting means for detecting brightness information indicating the brightness of the subject, and whether the brightness information detected by the brightness information detecting means is equal to or higher than a predetermined threshold value Determining means for determining whether or not the brightness is equal to or higher than a predetermined threshold value, and the color temperature of the subject is equal to or higher than a first color temperature; When the color temperature becomes equal to or less than the color temperature, the output gains of the R, G, and B signals are controlled so that the white balance is obtained at a color temperature lower than the white balance target value calculated by the arithmetic means. When the brightness is determined to be equal to or higher than a predetermined threshold value by the determination means, and the color temperature of the subject has risen above the second color temperature, the color temperature defining the upper limit of the output gain of the B signal The R signal so that white balance is obtained,
The output gains of the G signal and the B signal are controlled, and the determination unit determines that the brightness is equal to or less than the predetermined threshold, and the color temperature of the subject is equal to or higher than the first color temperature, and
If the temperature falls below the second color temperature, the second color of the subject
As the color temperature rises to the color temperature of R, the white balance follows the white balance target value.
The output gains of the signal, the G signal, and the B signal are controlled, and the determination means determines that the brightness is equal to or less than the predetermined threshold value, and is equal to or higher than a second color temperature higher than the first color temperature. Control means for controlling output gains of the R signal, the G signal, and the B signal such that when the color temperature of the subject increases, a white balance is obtained with a white balance target value calculated from the second color temperature. It is characterized by having.

In order to achieve the above object, the white balance control method according to the present invention is a reference for adjusting white balance from R, G, and B signals obtained when an outdoor subject is imaged. Detecting a color temperature of the subject, calculating a white balance target value that is a target value for white balance adjustment based on the detected color temperature, detecting brightness information indicating the brightness of the subject, and detecting It is determined whether the brightness information obtained is brightness equal to or higher than a predetermined threshold. When the brightness information is brightness equal to or higher than the predetermined threshold, it is determined that white balance control is performed on the sky in the subject. When the color temperature of the subject becomes equal to or higher than the first color temperature and equal to or lower than the second color temperature, the white temperature is lower than the calculated white balance target value. As Balance is taken above R
The output gains of the signals, the G signal, and the B signal are controlled, and when the brightness is equal to or more than the predetermined threshold value, it is determined that the white balance control for the sky in the subject is performed, and the second gain is determined.
When the color temperature of the subject rises above the color temperature of the above, the output gains of the R, G, and B signals are controlled so that white balance is achieved at a color temperature that defines the upper limit of the output gain of the B signal. When the brightness is equal to or less than the predetermined threshold, it is determined that white balance control is performed on the shade in the subject, and the color temperature of the subject up to the second color temperature is increased. The output gains of the R, G, and B signals are controlled so that the white balance follows the white balance target value. When the brightness is equal to or less than the predetermined threshold, the white balance control for the shade in the subject is performed. And the first
When the color temperature of the subject rises above a second color temperature higher than the color temperature of the R signal and the G signal so that a white balance is obtained with a white balance target value calculated from the second color temperature. The output gain of the signal and the B signal is controlled.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a white balance control device and a white balance control method according to the present invention will be described in detail with reference to the drawings.

The present invention is applied to a white balance control device 10 shown as a block diagram in FIG.

The white balance control device 10 includes a lens 1, an image sensor 2, a signal processing IC 3, and a microcomputer 4.

The lens 1 forms an image of incident light from a subject on an imaging surface of an imaging device 2.

The image pickup device 2 is, for example, a CCD (Charge-Cou
pled Device) is used. The imaging device 2 converts the image light formed on the imaging surface by the lens 1 into an electric signal, and sends the electric signal to the color signal processing unit 31 and the luminance signal processing unit 32 of the signal processing IC 3.

An iris diaphragm (not shown) for adjusting the amount of light is provided between the lens 1 and the image sensor 2.
The iris diaphragm is an AE (Automati
c Exposure). Further, when the white balance control device 10 is applied to a digital still camera,
The white balance control device 10 is provided with a shutter for cutting incident light.

Therefore, the brightness of the image light formed on the image pickup device 2 is obtained by adjusting the light incident on the lens 1 as described above.

The image sensor 2 is located downstream of the image sensor 2.
AGC (Automatic Gain Control), not shown, that adjusts the gain of the electric signal sent from the
The electric signal whose output level is kept constant is input to the signal processing IC 3 via the AGC.

The signal processing IC 3 includes a color signal processing unit 31 and
A luminance signal processing unit 32 and a white balance amplifier 33 are provided.

The color signal processing section 31 converts the electric signal supplied from the image sensor 2 into R, G, B signals, and sends the R, G, B signals to the microcomputer 4 as color input signals. Further, the color signal processing section 31 supplies the R, G, B signals converted from the electric signals to the white balance amplifier 33.

The luminance signal processing section 32 converts the electric signal supplied from the image pickup device 2 into brightness information of a subject and sends it to the microcomputer 4. The subject brightness information is the brightness of the subject that can be estimated from the amount of light received by the image sensor 2, the amount of the iris diaphragm, the shutter speed, the AGC control value, and the like.

The white balance amplifier 33 amplifies and attenuates R, G, and B signals, which are color input signals sent from the color signal processing unit 31, to predetermined values based on a control signal from a microcomputer 4 described later. To correct and output.

The microcomputer 4 performs control for adjusting the white balance based on the color input signal sent from the color signal processing section 31.

In order to adjust the white balance, usually, the whitest part of the input color input signal is extracted, its color temperature is obtained, and the obtained color temperature is calculated based on the achromatic color on the blackbody radiation curve. The output gains of the R, G, and B signals are controlled so as to achieve the white color temperature.

Here, for example, R, which is a color input signal,
A signal whose luminance level is equal to or higher than a predetermined threshold value and a signal whose luminance level is equal to or lower than the threshold value are extracted from the G and B signals.
Of the color temperatures obtained by integrating the G and B signals, the R, G and B signals that are approximated on the blackbody radiation curve are values to be drawn in to adjust the white balance.

Note that the method of extracting the value to be drawn is not limited to this, and a method other than the above method may be used.

The microcomputer 4 performs a predetermined operation from the brightness information sent from the luminance signal processing section 32 and the color temperature obtained from the color input signal sent from the color signal processing section, and performs a white balance amplifier 33. A control signal for controlling how much the R, G, and B signals sent from the color signal processing unit 31 are amplified,
It is sent to the white balance amplifier 33. In order to obtain white balance, R drawn in as described above,
Since it is sufficient that the output gains of the G and B signals are the same, R,
The amplification amounts of the G and B signals are calculated, for example, by taking the difference between the R signal and the G signal and the difference between the B signal and the G signal, assuming that the G signal has a constant value.

The microcomputer 4 controls each part of the white balance control device 10 as a whole.

Next, the operation of adjusting the white balance by the white balance controller 10 will be described with reference to the flowchart shown in FIG.

First, when incident light from a subject enters the lens 1, the incident light is imaged on the image sensor 2 as described above, converted into an electric signal by the image sensor 2, and converted into a color signal processing unit 31.
Is sent to the luminance signal processing unit 32. Color signal processing unit 3
1 is R, from the electric signal sent from the image sensor 2
G and B signals are generated, and the R, G, and B signals are sent to a white balance amplifier, and the R, G, and B signals are sent to a microcomputer as color input signals. On the other hand, the luminance signal processing unit 32
Converts the transmitted electric signal into brightness information and transmits it to the microcomputer 4.

In step S1, the microcomputer 4 determines whether or not the sent brightness information is equal to or more than the parameter A. If the brightness information is not equal to or more than the parameter A, the process proceeds to step S2. If so, the process proceeds to step S4.

Here, the parameter A will be described with reference to FIG.

The parameter A is a threshold value for determining whether the subject is indoors or outdoors, based on the brightness information obtained by the brightness signal processing section 32.

If the current brightness information is equal to or greater than the parameter A, the subject is determined to be outdoors, and if the current brightness information is equal to or less than the parameter A, the subject is determined to be indoors.

In step S2, the microcomputer 4 obtains a color temperature from the color input signal sent from the color signal processing section 31 and calculates an optimum white balance output target value when a subject is indoors.

In step S3, the microcomputer 4 calculates an appropriate white balance output value for indoor photographing from the white balance output target value calculated in step S2 and the current white balance output value, and calculates the calculated white balance. R,
A control value for controlling the G and B signals is generated and sent to a white balance amplifier.

In step S4, the microcomputer 4 calculates an optimum white balance output target value from the color temperature of the color input signal sent from the color signal processing section 31 when the subject is outdoors. The white balance target value is usually determined so as to follow the color temperature of the color input signal.
Sets the white balance target value so that the white balance is obtained at the above-mentioned predetermined color temperature without following the color input signal. As described above, the upper limit of the color temperature of the color input signal for setting the white balance target value so as to follow the color input signal is set as the parameter D.

In step S5, the microcomputer 4 determines whether or not the brightness information sent from the brightness signal processing section 32 is equal to or larger than the parameter B. If not, the process proceeds to step S6. ,
If it is equal to or more than the parameter B, the process proceeds to step S7.

Here, the parameter B will be described.
The parameter B is based on the brightness information obtained by the luminance signal processing unit 32, whether the subject currently contains more sky than the shade, or whether the subject contains more shade and less sky. Is a threshold for judging.

If the current brightness information is greater than or equal to the parameter B, it is determined that the subject contains more sky than the shaded part. It is determined that there are more shaded parts than the part.

In step S6, the microcomputer 4 calculates an appropriate white balance output value for outdoor photography in which there are more shades than the sky based on the white balance output target value calculated in step S4 and the currently set white balance output value. Is calculated, and control values for controlling the R, G, and B values are generated so as to be the calculated white balance output values, and are sent to the white balance amplifier.

When the microcomputer 4 determines from the brightness information sent from the luminance signal processing section 32 that the subject has many shades outdoors, when the subject has a high color temperature, the microcomputer 4 , FIG.
The color input signal (○) of the area shown as outdoor (shade) is transmitted from the color signal processing unit 31. This color input signal (○)
, The microcomputer calculates the white balance output target value (た) as obtained in step S4.
Here, the white balance output target value is obtained so as to follow the color temperature of the color input signal (信号), and the white balance output calculation result (◎) is obtained so as to match the result. Since the subject, in this case, the subject in the shade portion is drawn into the white balance adjustment, it is possible to prevent the subject from becoming bluish when photographing in the shade.

As described in step S4, when a color input signal (○) exceeding the color temperature of the parameter D is input to the microcomputer 4, the microcomputer 4 does not follow the white balance target value. Is set as if white balance is to be achieved with the color temperature of parameter D. In the white balance output calculation, an output value that becomes the white balance target value set in this way is calculated. Therefore, here, when the color input signal having the color temperature equal to or higher than the parameter D is input,
It judges that the sky was the subject in the shade outdoors,
Following this, the threshold value is set to prevent white balance from being obtained. Therefore, even if a color input signal equal to or more than the parameter D is input, the shade will not be output with a bluish hue.

In step S7, the microcomputer 4 determines whether or not the color input signal sent from the color signal processing section 31 is equal to or greater than the parameter D. If not, the microcomputer 4 proceeds to step S8. If it is equal to or greater than the parameter D, the process proceeds to step S9.

As described above, the parameter D is a color temperature that becomes the upper limit of the target value of the white balance when the color input signal has a color temperature equal to or higher than the parameter D.

In step S8, the microcomputer 4 determines from the color temperature of the color input signal that the subject contains a lot of sky, and determines the white balance output target value calculated in step S4 and the current setting. An appropriate white balance output value for outdoor shooting with a lot of sky is calculated from the white balance output value, and a control value for controlling R, G, B values is generated so as to be the calculated white balance output value, and a white balance amplifier is generated. Send to

The white balance output value calculated in the case of step S8 is different from that calculated in step 6 described above so as to follow the white balance target value when the parameter is equal to or less than the parameter D. Calculate the white balance output value. That is,
In step S8, since it is determined that the subject contains a lot of sky, when an input color signal having a color temperature equal to or higher than the parameter C is input, the white color is changed to an achromatic white. The white balance output is set to a low color temperature output in order to intentionally increase the bluish in the balance.

Specifically, as shown as an outdoor (sky A) in FIG. 4, the color temperature at which the white balance starts to shift is defined as a parameter C, and when the color temperature of the color input signal becomes the parameter D, the bluish color is maximized. The parameter E which is the lower limit value of the white balance is determined so that even if a color input signal having a color temperature equal to or higher than the parameter C is inputted, the bluish color does not suddenly increase and unnaturalness occurs in step S4. By performing linear interpolation calculation between the obtained white balance target value and the parameter E, the white balance is smoothly shifted in the direction in which the bluish color is enhanced.

When the independent variable is parameter C, the white balance target value calculated from the color temperature of parameter C is the dependent variable, and when the independent variable is parameter D, parameter E is the dependent variable. Since these are linear equations, by solving a simultaneous equation in which these values are substituted, a linear interpolation calculation equation as shown in equation (1) is obtained.

[0048]

(Equation 1)

The output value of the white balance according to the linear interpolation calculation formula of the equation (1) is obtained by gradually setting the white balance target value in the white balance direction in the outdoor (sky A) area in FIG. It has stopped following, and has changed to a direction in which white balance is not actively taken.

The microcomputer 4 generates a control value for controlling the output gain of the B signal so that the value obtained from the linear interpolation formula becomes a white balance output value, and sends the control value to the white balance amplifier 33. Send out.

In step S9, as shown in the outdoor (sky B) area of FIG. 4, the microcomputer 4 captures only the clear blue sky, regardless of the color input signal of any color temperature equal to or higher than the parameter D. The white balance output is determined to be the value of the parameter E.

In this manner, the microcomputer 4 compares the color temperature of the color input signal and the parameter B with the microcomputer 4 to determine whether the subject has many shades.
It is determined whether the subject has a lot of sky, and when it is determined that the subject has a lot of shade, the white balance of the shaded subject is controlled by controlling the white balance to follow the color temperature rise of the subject below the parameter D. When it is determined that the subject has a lot of sky, the white balance output is intentionally set as the color temperature of the subject increases in the temperature range of the parameter C or more and the parameter D or less. By setting the color temperature output lower than the balance target value, the blue of the sky does not become whitish and the blue can be emphasized.

[0053]

As is apparent from the above description, the white balance control device of the present invention performs white balance control on the sky in the subject by the judging means based on the brightness information of the subject, or executes shading in the subject. It is determined whether white balance control is to be performed on the sky in the subject. If the color temperature of the subject is equal to or higher than the first color temperature and equal to or lower than the second color temperature, the calculating means R, so that white balance is obtained at a color temperature lower than the white balance target value calculated in
The output gains of the G and B signals are controlled, and when the color temperature of the subject is equal to or higher than the second color temperature, the R and R signals are adjusted so that the white balance is obtained at the color temperature that defines the upper limit of the output gain of the B signal.
When the output gain of the signal, the G signal, and the B signal is controlled to perform white balance control for the shade in the subject, and when the color temperature of the subject is equal to or higher than the first color temperature and equal to or lower than the second color temperature, The output gains of the R, G, and B signals are controlled so that the white balance follows the white balance target value as the color temperature of the subject increases to the second color temperature. When the color temperature of the subject rises above the second color temperature which is also high, the R signal, the G signal, and the B signal are adjusted so that the white balance is obtained with the white balance target value calculated from the second color temperature. By controlling the output gain, it is possible to output an optimal white balance in a high color temperature environment such as a shade or sky in outdoor photography.

As is apparent from the above description, the white balance control method of the present invention performs white balance control on the sky in the subject or white balance control on the shade in the subject based on the brightness information of the subject. If the color temperature of the subject is equal to or higher than the first color temperature and equal to or lower than the second color temperature, it is determined that the white balance control is to be performed on the sky in the subject. The output gains of the R, G, and B signals are controlled so that a white balance is obtained at the color temperature. When the color temperature of the subject is equal to or higher than the second color temperature, the color temperature that defines the upper limit of the output gain of the B signal In the case where the output gains of the R signal, the G signal, and the B signal are controlled so that the white balance is obtained in Temperature first color temperature or above, and,
When the color temperature is equal to or lower than the second color temperature, the output gains of the R, G, and B signals are adjusted so that the white balance follows the white balance target value as the color temperature of the subject increases to the second color temperature. When the color temperature of the subject increases at a second color temperature higher than the first color temperature or higher, the white balance is set at a white balance target value calculated from the second color temperature. By controlling the output gain of the R signal, G signal, and B signal, in outdoor shooting,
It is possible to output an optimal white balance in a high color temperature environment such as shade and sky.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a main configuration of a white balance control device shown as an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a white balance operation in the white balance control device.

FIG. 3 is a diagram illustrating a parameter A and a parameter B in the white balance control device.

FIG. 4 is a diagram for explaining a state of white balance control when the subject is determined to be outdoors in the white balance control device.

FIG. 5 is a diagram for explaining a relationship between a blackbody radiation curve and a color temperature.

[Explanation of symbols]

Reference Signs List 1 lens, 2 image sensor, 3 signal processing IC, 4 microcomputer, 10 white balance controller, 31 color signal processor, 32 luminance signal processor, 33
White balance amplifier

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C065 AA01 AA03 BB02 CC02 CC03 DD02 GG15 GG32 5C066 AA01 BA20 CA08 EA03 EA15 EE04 GA01 GA02 GA05 GA32 GA33 GB01 KA12 KD02 KD06 KE01 KP02 5C079 HB01 JA23

Claims (5)

[Claims] 1. An image pickup apparatus that obtains an image of an outdoor subject when capturing an image of an outdoor subject.
A color temperature detecting means for detecting a color temperature of the subject as a reference for adjusting a white balance from the signal, the G signal, and the B signal; and adjusting a white balance based on the color temperature detected by the color temperature detecting means. Calculating means for calculating a white balance target value which is a target value of: brightness information detecting means for detecting brightness information indicating the brightness of the subject; and brightness information detected by the brightness information detecting means. Determining means for determining whether the brightness is equal to or higher than a predetermined threshold value; determining that the brightness is equal to or higher than the predetermined threshold value; When the color temperature becomes equal to or lower than the second color temperature, the white balance is set so that the white balance is obtained at a color temperature lower than the white balance target value calculated by the calculation means. R signal, G
The output gains of the signal and the B signal are controlled. If the brightness of the object is higher than the predetermined threshold value by the determination means and the color temperature of the object is higher than the second color temperature, The output gains of the R, G, and B signals are controlled so that white balance is achieved at a color temperature that defines the upper limit of the output gain of the signal. When the color temperature of the subject becomes equal to or higher than the first color temperature and equal to or lower than the second color temperature, the color temperature of the subject increases to the second color temperature. Controlling the output gains of the R signal, the G signal, and the B signal so that the white balance follows the white balance target value, and the determination means determines that the brightness is equal to or less than the predetermined threshold value, The first When the color temperature of the subject rises above a second color temperature higher than the temperature, the R signal, the G signal, and the white balance are set so that a white balance is obtained with a white balance target value calculated from the second color temperature. A white balance control device comprising control means for controlling an output gain of a B signal. 2. The control means determines that the brightness is equal to or higher than a predetermined threshold value by the determination means, and the color temperature of the subject is equal to or higher than a first color temperature and the second color temperature is determined. In the following cases, the first color temperature and the white balance color temperature defined so that the output gain of the B signal is maximized when the subject is at the second color temperature are set to 1 The R signal and the G signal are set so that a white balance output value calculated by performing a linear interpolation calculation of a dimension is obtained.
2. The white balance control device according to claim 1, wherein output gains of the signal and the B signal are controlled. 3. The control means performs white balance control with respect to the sky when the brightness information is equal to or more than the predetermined threshold value, and performs white balance control with respect to shade when the brightness information is equal to or less than the predetermined threshold value. The white balance apparatus according to claim 1, wherein the white balance is controlled. 4. An R obtained when an outdoor subject is imaged.
The color temperature of the subject as a reference for adjusting the white balance is detected from the signal, the G signal, and the B signal, and a target white balance value is calculated based on the detected color temperature. Detecting brightness information indicating the brightness of the subject; determining whether the detected brightness information is brightness equal to or greater than a predetermined threshold; and determining brightness equal to or greater than the predetermined threshold. At this time, it is determined that white balance control for the sky in the subject is performed,
When the color temperature of the subject becomes equal to or higher than the first color temperature and equal to or lower than the second color temperature, the R signal is set so that a white balance is obtained at a color temperature lower than the calculated white balance target value. , Controlling the output gains of the G signal and the B signal. When the brightness is equal to or more than the predetermined threshold value, it is determined that the white balance control for the sky in the subject is performed.
When the color temperature of the subject rises above the second color temperature, the output of the R signal, the G signal, and the B signal is performed so that white balance is achieved at a color temperature that defines an upper limit of the output gain of the B signal. The gain is controlled, and when the brightness is equal to or less than the predetermined threshold value, it is determined that the white balance control for the shade in the subject is performed, and the color temperature of the subject up to the second color temperature is increased. The output gains of the R, G, and B signals are controlled so that the white balance follows the white balance target value. When the brightness is equal to or less than the predetermined threshold, the white gain against the shade in the subject is reduced. If it is determined that balance control is to be performed and the color temperature of the subject has risen above a second color temperature higher than the first color temperature, a white balance calculated from the second color temperature is calculated. A white balance control method, comprising: controlling output gains of the R, G, and B signals so that a white balance is obtained with a lance target value. 5. It is determined that the brightness is equal to or higher than the predetermined threshold, and the color temperature of the subject is equal to or higher than a first color temperature.
And a color temperature of a white balance defined so that an output gain of the B signal is maximized when the subject is at the second color temperature when the temperature is equal to or lower than the second color temperature. And one-dimensional linear interpolation calculation using the color temperatures of the above, and the output gains of the R, G, and B signals are controlled so as to obtain white balance output values calculated by the one-dimensional linear interpolation calculation. The white balance control method according to claim 4, wherein: