JPH05145930A - Automatic white balance controller - Google Patents

Abstract

PURPOSE:To apply a color expression to a video signal, corresponding to the temperature of an atmosphere by detecting the temperature of the atmosphere, in which an object is set, and reflecting this temperature onto automatic white balance control. CONSTITUTION:The distortion of color balance in an object 9 is detected by a color temperature detecting means 5, this is adjusted by color balance adjusting means 6, 31 and 33, and the white balance of the video signals obtained by picking up the image of the object 9 is controlled. At such a time, a temperature detecting means 7 detects the temperature of the environment, in which the object 9 is set, and a correcting means 8 corrects the color balance adjusting means 31 and 33 based on this temperature detecting output. Thus, the environment temperature is reflected onto the white balance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic white balance control device, and more particularly to an automatic white balance control device suitable for expressing the outside air temperature of an environment where a subject is placed.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional automatic white balance control device, and particularly illustrates a configuration of a type in which automatic white balance control is controlled based on a color temperature of a light source. In the figure, reference numeral 1 denotes an image pickup unit having a built-in lens unit and a camera unit for picking up an image of a subject 9 to which light source light L from outside light or illumination light is given and outputting video signals of red component, green component, and blue component, 21. Is a preamplification circuit for red signal that amplifies the red component of the video signal from the image pickup unit 1, 22 is a preamplification circuit for green signal that amplifies the green component of the video signal from the image pickup unit 1, and 23 is an image pickup unit 1. A blue signal preamplifier circuit for amplifying the blue component of the video signal from 1. 1, 31 is a red signal gain control circuit for controlling the gain of the red component from the red signal preamplifier circuit 21, and 33 is a blue signal preamplifier. The blue signal gain control circuit 4 for controlling the gain of the blue component from the amplifier circuit 23 is a red component of the video signal from the red signal gain control circuit 31 and the green component of the video signal from the green signal preamplifier circuit 22. And green signal gain control A process encoder circuit for matrix-calculating the blue component of the video signal from the path 33 to encode the composite video signal V, a color temperature detector 5 for detecting the color temperature of the light source light L in the environment where the subject 9 is placed, 6 Is based on the color temperature of the light source light L detected by the color temperature detector 5 and is based on the red signal preamplifier circuit 2
1. Among the red, green, and blue components obtained by the green signal preamplifier circuit 22 and the blue signal preamplifier circuit 23, the gains of the red component and the blue component are the red signal gain control circuit 31 and the blue signal, respectively. It is a white balance control signal generator that generates a control signal for changing through the gain control circuit 33.

The operation of the above arrangement will be described below. The color temperature detector 5 has a first light receiving element which is mainly sensitive to light of a short wavelength and a second light receiving element which is mainly sensitive to light of a long wavelength, and outputs of these two light receiving elements. The color temperature of the light source light L such as the external light or the illumination light given to the subject 9 is detected from the ratio and the signal corresponding to this is sent to the white balance control signal generator 6. On the other hand, the subject 9 illuminated by the light source light L
The image is captured by the image pickup unit 1 for each of the red component, the green component, and the blue component of the video signal, and the red signal preamplification circuit 21, the green signal preamplification circuit 22, and the blue signal preamplification circuit 23. Is amplified by.

Here, depending on the color temperature of the light source light L, the red component of the video signal of the subject 9 imaged by the image pickup unit 1,
The balance of the green component and the blue component, that is, the white balance is deviated, and accurate color reproduction of the subject 9 cannot be performed. Therefore, the light source light L detected by the color temperature detector 5
White balance control signal generator 6 based on the color temperature of
Of the blue component of the video signal from the red signal gain control circuit 31 and the blue signal preamplification circuit 23, which controls the gain of the red component of the video signal from the red signal preamplification circuit 21 by the control signal obtained in By controlling the blue signal gain control circuit 33 for controlling the gain to change the ratio of the video signal from the green signal preamplifier circuit 22 to the green component, the ratio of the red component and the blue component of the video signal to the green component is changed. The color of the subject 9 is accurately reproduced regardless of the color temperature of the light source light L by correcting the white balance.

The respective color components of the video signal obtained as described above are given to the process encoder circuit 4, where they are subjected to matrix calculation and encoding processing, and N
It is externally derived as a composite video signal V conforming to a system such as TSC or PAL.

[0006]

As described above, the conventional automatic white balance control device detects the red component, the green component, and the blue component of the video signal based on the color temperature of the light source light L detected by the color temperature detector 5. Since the color balance of each component is corrected to correct the deviation of the color temperature of the light source light L to faithfully reproduce the color of the subject 9, for example, even when the temperature is high near the fire and the outside air temperature is high. A video signal with little redness can be obtained from the color of the subject 9, or a video signal can be obtained in which the color of the subject 9 looks reddish and warm even in a cold atmosphere such as snow. There was a problem that the expressiveness of the atmosphere that human beings felt was insufficient. This is exactly the same in the configuration of the method of controlling the auto white balance based on the balance of each color component of the video signal, which has been one of the causes of limiting the expressive power of the video camera.

The present invention has been made to solve the above-mentioned problems, and detects the temperature of the atmosphere in which the subject 9 is placed and reflects this in the automatic white balance control, thereby An object of the present invention is to provide an automatic white balance control device capable of incorporating a color expression according to temperature in a video signal to enhance the expression capability of a color video camera or the like.

[0008]

To achieve the above object, the present invention provides a color temperature detecting means for detecting the color temperature of a light source in an environment where a subject is placed, and an image obtained by imaging the subject. Color balance adjusting means for adjusting the color balance of the signal based on the output of the color temperature detecting means, temperature detecting means for detecting the environmental temperature of the subject, and the color based on the output of the temperature detecting means. The present invention provides an automatic white balance control device including a correction unit that adds a correction to a balance adjustment unit.

In order to achieve the above object, the present invention is based on a color balance detecting means for detecting a color balance deviation from a video signal obtained by picking up an image of an object, and an output of the color balance detecting means. Color balance adjusting means for adjusting the color balance of the video signal, temperature detecting means for detecting the environmental temperature of the subject, and correction for correcting the color balance adjusting means based on the output of the temperature detecting means. And an automatic white balance control device including the means.

[0010]

In each of the above means, the automatic white balance control device of the present invention detects the deviation of the color balance of the object by the color temperature detecting means or the color balance detecting means, and adjusts this by the color balance adjusting means to adjust the object. In taking a white balance of a video signal obtained by capturing an image, the ambient temperature of the subject is detected by a temperature detecting means, and the correcting means corrects the color balance adjusting means based on the temperature detection output. The ambient temperature is reflected in the white balance.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a block diagram of an automatic white balance control apparatus according to an embodiment of the present invention, and particularly illustrates a configuration of a type in which automatic white balance control is controlled based on a color temperature of a light source. Is. In the figure, 7 is an outside air temperature detector that detects the temperature of the environment in which the subject 9 is placed, and 8 is a red signal gain control circuit 31 and a blue signal gain control circuit based on the temperature detected by the outside air temperature detector 7. 33 is a white balance correction signal generator for generating a correction signal for correcting the gains of the red component and the blue component of the video signal in 33.

The operation of the above arrangement will be described below. The color temperature detector 5 is an external light given to the subject 9 from the ratio of the outputs of the first light receiving element which is mainly sensitive to light of short wavelength and the second light receiving element which is mainly sensitive to light of long wavelength. Alternatively, the color temperature of the light source L such as illumination light is detected, and a signal corresponding to this is sent to the white balance control signal generator 6. On the other hand, the image of the subject 9 given the light by the light source light L is picked up by the image pickup unit 1 and the red signal preamplification circuit 21 and the green signal for the red component, the green component and the blue component of the video signal are obtained. It is amplified by the preamplifier circuit 22 and the green signal preamplifier circuit 23.

Here, depending on the color temperature of the light source light L, the red component of the video signal of the subject 9 imaged by the image pickup unit 1,
Since the balance of the green component and the blue component, that is, the white balance is deviated and the color of the subject 9 cannot be reproduced accurately, the white balance control is performed based on the color temperature of the light source light L detected by the color temperature detector 5. A video signal from a red signal gain control circuit 31 and a blue signal preamplification circuit 23 that controls the gain of the red component of the video signal from the red signal preamplification circuit 21 by the control signal obtained by the signal generator 6. By controlling the gain control circuit 33 for the blue signal for controlling the gain of the blue component of the green signal and changing the ratio of the video signal from the preamplifier circuit 22 for the green signal to the green component. An operation is performed such that the ratio of the components is corrected to achieve white balance, and the color of the subject 9 is accurately reproduced regardless of the color temperature of the light source light L.

On the other hand, the temperature of the environment in which the subject 9 is detected detected by the outside air temperature detector 7 is given to the white balance correction signal generator 8. The white balance correction signal generator 8 is used when the outside air temperature is high. , The subject 9 imaged by the image pickup unit 1 is enhanced so that the tint of the subject 9 imaged by the image pickup unit 1 is increased and the bluishness is reduced so that the tint is appropriate when the temperature is high. A correction signal is output to the red signal gain control circuit 31 and the blue signal gain control circuit 33 so that the blue tint is strengthened and the red tint is weakened so as to be suitable when the temperature is low. As a result, the red signal gain control circuit 31 and the blue signal gain control circuit 33 generate the video signal based on the correction signal from the white balance correction signal generator 8 in addition to the gain control signal from the white balance control signal generator 6. It controls the gain of the red and blue components. By such control, when the color temperature deviation of the light source light L in the atmosphere in which the subject 9 is placed is removed and the temperature is high due to the temperature in the atmosphere in which the subject 9 is placed in comparison with the state where the white balance is perfectly achieved. Enhances redness and weakens blueness to reflect a high temperature state in the video signal, enhances redness when the temperature is low, and weakens redness to reflect a low temperature state in the video signal.

The respective color components of the video signal obtained as described above are given to the process encoder circuit 4, where they are subjected to matrix calculation and encoding processing, and N
It is externally derived as a composite video signal V conforming to a system such as TSC or PAL.

As described above, the outside temperature of the atmosphere in which the subject 9 is placed is detected by the outside temperature detector 7, and the white balance correction signal generator 8 detects the red signal gain control circuit 31 and the blue signal gain control circuit 33. By correcting the gain with respect to, the temperature of the atmosphere in which the subject 9 is placed can be reflected in the video signal, and the expression capability of the color video camera can be enhanced.

Embodiment 2 FIG. 2 is a block diagram of an automatic white balance control apparatus according to another embodiment of the present invention. In particular, an automatic white balance control is performed on the basis of each color component of the video signal obtained. 1 illustrates a configuration. In the figure, reference numeral 60 denotes a red component of the video signal from the red signal preamplification circuit 21, a green component of the video signal from the green signal preamplification circuit 22 and a blue component of the video signal from the blue signal preamplification circuit 23. It is a white balance control circuit which detects a deviation of white balance based on the component and gives a gain control signal to the red signal gain control circuit 31 and the blue signal gain control circuit 33.

The operation of the above arrangement will be described below. The image of the subject 9 provided with the light from the light source light L is captured by the imaging unit 1 and the red component of the video signal,
Red signal preamplifier circuit 2 for each of the green and blue components
1. Amplified by the green signal preamplifier circuit 22 and the blue signal preamplifier circuit 23. On the other hand, the white balance control circuit 60 is a circuit having a function of intelligently detecting a deviation of white balance from each of the red, green, and blue color components of the image signal of the subject 9 imaged by the image pickup unit 1, and for example, a white signal is detected for a high level signal. It has a well-known configuration that detects a color shift based on an empirical rule such as a large number of pixels and generates a white balance control signal.

Now, depending on the color temperature of the light source light L, the balance of the red, green and blue components of the image signal of the subject 9 imaged by the image pickup unit 1, that is, the white balance is deviated, and the accurate subject 9 image is obtained. Since color reproduction cannot be performed, the red signal gain control circuit 31 for controlling the gain of the red component of the video signal from the red signal preamplification circuit 21 by the white balance control signal obtained by the white balance control circuit 60. And a blue signal gain control circuit 33 for controlling the gain of the blue component of the video signal from the blue signal preamplification circuit 23 to change the ratio of the video signal from the green signal preamplification circuit 22 to the green component. As a result, the ratio of the red component and the blue component of the video signal to the green component is corrected to achieve white balance. As a result, the operation of accurately reproducing the color of the subject 9 regardless of the color temperature of the light source light L is performed.

On the other hand, the temperature of the environment in which the subject 9 is detected detected by the outside air temperature detector 7 is given to the white balance correction signal generator 8. The white balance correction signal generator 8 is used when the outside air temperature is high. , The subject 9 imaged by the image pickup unit 1 is enhanced so that the tint of the subject 9 imaged by the image pickup unit 1 is increased and the bluishness is reduced so that the tint is appropriate when the temperature is high. A correction signal is output to the red signal gain control circuit 31 and the blue signal gain control circuit 33 so that the blue tint is strengthened and the red tint is weakened so as to be suitable when the temperature is low. As a result, the red signal gain control circuit 31 and the blue signal gain control circuit 33 add the red component of the video signal based on the correction signal from the white balance correction signal generator 8 in addition to the gain control signal from the white balance control circuit 60. And the gain of the blue component will be controlled. By such control, when the color temperature deviation of the light source light L in the atmosphere in which the subject 9 is placed is removed and the temperature is high due to the temperature in the atmosphere in which the subject 9 is placed in comparison with the state where the white balance is perfectly achieved. Enhances redness and weakens blueness to reflect a high temperature state in the video signal, enhances redness when the temperature is low, and weakens redness to reflect a low temperature state in the video signal.

Each color component of the video signal obtained as described above is given to the process encoder circuit 4, where it is subjected to matrix calculation and encoding processing, and N
It is externally derived as a composite video signal V conforming to a system such as TSC or PAL.

As described above, the outside temperature of the atmosphere in which the subject 9 is placed is detected by the outside temperature detector 7, and the white balance correction signal generator 8 detects the red signal gain control circuit 31 and the blue signal gain control circuit 33. By correcting the gain and reflecting the temperature of the atmosphere in which the subject 9 is placed in the video signal, the expression capability of the color video camera can be similarly enhanced.

In the configuration of FIG. 2, the output signals of the red signal preamplifier circuit 21, the green signal preamplifier circuit 22, and the blue signal preamplifier circuit 23 can be led to the white balance control circuit 60. Although an open loop type white balance control system for controlling the gains of the red signal gain control circuit 31 and the blue signal gain control circuit 33 by the white balance control signal has been illustrated, the red signal gain control circuit 31 and the blue signal gain control are described. The same effect can be obtained by forming a control loop having a so-called feedback loop in which the output of the circuit 33 is given to the white balance control circuit 60 to control the gains of the red signal gain control circuit 31 and the blue signal gain control circuit 33. Obtainable. In this case, the correction output of the white balance correction signal generator 8 has an offset in the control signals of the red signal gain control circuit 31 and the blue signal gain control circuit 33, or the red signal gain control circuit 31 and the blue signal gain control circuit. The outside air temperature is reflected in the white balance control by the gain control of another gain control circuit provided in the output stage of the circuit 33.

In each of the above embodiments, the process encoder is adjusted after the color balance is adjusted by changing the ratio of the red component, the blue component and the green component of the red, green and blue components of the video signal. Although the circuit has been shown as an example of a structure in which a composite video signal is used, it goes without saying that the same effect can be obtained even if the structure is such that the luminance signal and the color difference signal are obtained by the process processing and then the balance of the color difference signal is adjusted. ..

[0026]

As described above, according to the present invention,
Since the outside temperature is reflected in the white balance control, the atmosphere due to the outside temperature can be included in the video signal in the form of color expression, and the expression capability of the color video camera can be enhanced.

[Brief description of drawings]

FIG. 1 is a block diagram of an automatic white balance control device according to an embodiment of the present invention.

FIG. 2 is a block diagram of an automatic white balance control device according to another embodiment of the present invention.

FIG. 3 is a block diagram of a conventional automatic white balance control device.

[Explanation of symbols]

 1 Imaging Unit 4 Process Encoder Circuit 5 Color Temperature Detector 6 White Balance Control Signal Generator 7 Outdoor Air Temperature Detector 8 White Balance Correction Signal Generator 9 Subject 21 Red Signal Preamplifier Circuit 22 Green Signal Preamplifier Circuit 23 Preamplifier circuit for blue signal 31 Gain control circuit for red signal 33 Gain control circuit for blue signal 60 White balance control circuit L Light source light

Claims (2)

[Claims] 1. A color temperature detecting means for detecting a color temperature of a light source in an environment where a subject is placed, and a color balance of a video signal obtained by imaging the subject is adjusted based on an output of the color temperature detecting means. Color balance adjusting means, temperature detecting means for detecting the environmental temperature of the subject, and correction means for correcting the color balance adjusting means based on the output of the temperature detecting means. Auto white balance control device. 2. A color balance detecting means for detecting a color balance deviation from a video signal obtained by picking up an image of a subject, and a color balance adjustment for adjusting the color balance of the video signal based on the output of the color balance detecting means. Means, a temperature detecting means for detecting the environmental temperature of the subject, and a correcting means for correcting the color balance adjusting means based on the output of the temperature detecting means. Balance control device.