JPH07123435A - White balance controller - Google Patents

Abstract

PURPOSE:To obtain a picture without any sense of incompatibility even used outdoors as well by relaxing the response characteristics of a white balance control operation rather than that of an indoor case when the outdoor state is discriminated by an indoor/outdoor discriminating means. CONSTITUTION:Light made incident on a lens 1 passes through an optical iris 8 and forms an image on a CCD 2. That output signal is separated into R, G and B signals by a color separation circuit 3. The R and B signals are inputted through R and B amplifier circuits 4 and 5, the G signal is directly inputted to a camera process and matrix circuit 6, and a luminance signal Y and color difference signals R-Y and B-Y are outputted to a video circuit 7 and integration circuits 17-19. At the circuits 17-19, color evaluated values (r) and (b) and a luminance evaluated value (y) are respectively outputted to gain control circuits 33 and 34 and a subtraction circuit 24. At the subtracter 24, that value is compared with a reference value Vref so as to provide an optimum exposing state, and a subtracted value M=Vref-y is inputted to an iris motor part 30 and an indoor/outdoor discrimination circuit 23. The circuit 23 outputs a control signal S corresponding to the outdoor photographic state to the circuit 34, and the response characteristics of the white balance control operation are made dull.

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 adjusting device for a color video camera which controls white balance based on an image pickup video signal obtained from an image pickup device.

[0002]

2. Description of the Related Art In a color video camera, it is necessary to adjust white balance in order to correct the difference in the wavelength distribution of light depending on the light source. This control is red (hereinafter R),
The ratio of the three primary color signals of blue (hereinafter B) and green (hereinafter G) is 1:
It is performed by adjusting the gain of each color signal so that the ratio becomes 1: 1. Generally, for example, as shown in Japanese Patent Laid-Open No. 62-35792 (H04N9 / 73), a method of adjusting the gain so that the integrated values of the color difference signals RY and BY of the screen become zero is used. Has been.

FIG. 7 is a block diagram of a white balance adjusting device using this method. The light passing through the lens 1 is photoelectrically converted by the image pickup device (CCD) 2 and then the color separation circuit 3
, The three primary color signals of R, G, and B are extracted, the G color signal is directly input, and the R and B color signals are passed through the R amplification circuit 4 and the B amplification circuit 5, and the camera process and the matrix circuit 6 are output.
Are input to the video circuit 7 and the luminance signal Y and the color difference signals RY and BY of red and blue are generated and sent to the video circuit 7.

At the same time, the two color difference signals are integrated in the integrating circuits 17 and 18, respectively, for a sufficiently long time, and the gain control circuits 13 and 14 are respectively amplified by the gain control circuits 13 and 14 so that the result becomes zero. Adjust the gain of.

[0005]

In the above-mentioned method, since the change of the light source is recognized after the white balance is once adjusted, the change of the output value of the integrating circuits 17 and 18 exceeds the preset threshold value. In that case, the white balance is adjusted again. Therefore, since there are many changes in the light source indoors, this method produces images that do not look uncomfortable.
Even though there is only sunlight outdoors, the color of the entire screen may change due to the unique color of the subject, resulting in an unsightly screen.

An object of the present invention is to provide a white balance adjusting device capable of making an image without a feeling of strangeness even outdoors.

[0007]

In order to solve the above problems, the present invention provides a white balance adjusting means for executing a white balance adjusting operation for controlling a gain of each color signal based on a picked-up video signal, and the image pickup device. Exposure adjusting means for issuing a diaphragm control signal to the diaphragm adjusting means to adjust the diaphragm amount of the diaphragm adjusting means so that the luminance signal level in the video signal becomes the optimum level;
An indoor / outdoor discriminating unit for discriminating between an indoor photographing state and an outdoor photographing state based on the diaphragm control signal or the diaphragm amount of the diaphragm adjusting unit is provided, and the response characteristic of the white balance adjusting operation is determined according to the output of the judging unit. I changed it.

Further, a white balance adjusting means for executing a white balance adjusting operation for controlling the gain of each color signal on the basis of the picked-up image signal, and a luminance signal level in the picked-up image signal,
Alternatively, an indoor / outdoor discriminating means for discriminating the indoor photographing state or the outdoor photographing state from the color signal level is provided, and the response characteristic of the white balance adjusting operation is changed according to the output of the discriminating means.

[0009]

When the indoor / outdoor discrimination means discriminates that it is outdoors, the response characteristic of the white balance adjusting operation becomes slower than in the case of indoors.

[0010]

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

FIG. 1 is a circuit block diagram of a white balance adjusting apparatus according to a first embodiment of the present invention. The light that has entered the lens 1 passes through the optical diaphragm bright light 8, is imaged on the CCD 2 and undergoes photoelectric conversion, and is then extracted by the color separation circuit 3 as three primary color signals of R, G, and B. The R and B signals of these three primary color signals are input to the camera process and matrix circuit 6 together with the G signal through the R amplification circuit 4 and the B amplification circuit 5, respectively, and the luminance signals Y and R, B
The respective color difference signals R-Y and B-Y are created, supplied to the video circuit 7 and subjected to known processing.

The R-Y and B-Y signals are supplied to the integrating circuits 18 and 17, respectively, and at the same time, the luminance signal Y is obtained.
Is supplied to the integrating circuit 19. In each integration circuit, the input signal is digitally integrated over a fixed time, for example, one field period, and the integrated values are obtained as the color evaluation values r and b and the brightness evaluation value y for each field.

The reference level of the color difference signals input to the integrating circuits 17 and 18, that is, the zero level, is preset to the level obtained when a perfect achromatic surface is photographed.
Therefore, it goes without saying that each color difference signal can take not only a positive value but also a negative value.

The brightness evaluation value y is input to the subtractor 24,
It is compared with a reference value Vref preset so as to obtain an optimum exposure state, and M = Vref-y is subtracted here, and this subtracted value M is supplied to the iris motor section 30 and the indoor / outdoor discrimination circuit 23. To be done.

The iris motor section 30 drives the iris motor in accordance with the subtracted value M to change the aperture amount of the optical aperture mechanism 8 and executes an automatic exposure adjustment operation for keeping the brightness of the screen at an optimum constant level. . That is, as the brightness evaluation value y increases, the subtraction value M decreases, and the optical diaphragm mechanism 8 operates in the closing direction to reduce the amount of light incident on the CCD 2. Conversely, when the brightness evaluation value y decreases, the subtraction value M increases, and the optical diaphragm mechanism 8 operates in the opening direction to increase the amount of light incident on the CCD 2.

On the other hand, the indoor / outdoor discrimination circuit 23 is provided with a threshold Vt for discriminating between indoor and outdoor. When the input subtraction value M is larger than the threshold Vt, the indoor photographing condition is set. Issuing the control signal S of H level,
On the contrary, when it is smaller than the threshold value, the control signal S of L level is issued on the assumption that it is in the outdoor photographing state.

The control signal S thus generated is input to the gain control circuits 33 and 34. Then, when it is determined that the indoor photographing state is entered and the H-level control signal S is input, the threshold value for recognizing the light source change is reduced to improve the response characteristic of the white balance adjustment operation. Therefore, it becomes possible to cope with a slight change in the light source indoors. Further, when it is determined that the camera is in the outdoor shooting state and the L-level control signal S is input, the threshold value for recognizing the light source change is increased, and the response characteristic of the white balance adjustment operation is made dull. Therefore, even if there is only sunlight, there is no need to re-correct for slight color changes in the input signal outdoors, but the colors of the entire screen change due to the unique colors of the subject, resulting in an unsightly screen. It will not be lost.

That is, the gain control circuit 33 operates like the flowchart shown in FIG. When the color evaluation value r is input for each field from the integrating circuit 17, the level of the control signal S is detected (S1). When the H level, that is, the indoor photographing state is detected, the difference between the previously input color evaluation value r ′ and the currently input color evaluation value r is the predetermined value AH.
Whether or not it is detected (S2), if the predetermined value AH or more, the gain control of the R amplification circuit 4 is performed (S3), and if it is less than the predetermined value AH, the gain control is not performed and the previous gain setting state is maintained. On the other hand, in S1, if it is detected that the L level, that is, the outdoor photographing state, the difference between the previously input color evaluation value r ′ and the currently input color evaluation value r is equal to or larger than the predetermined value AL. Whether or not it is detected (S4), if the value is equal to or larger than the predetermined value AL, the gain control of the R amplification circuit 4 is performed (S3), and if it is less than the predetermined value AL, the gain control is not performed and the previous gain setting state is maintained. here,
Since there is a magnitude relation of AH <AL, the threshold value for recognizing a light source change becomes small indoors and the threshold value for recognizing a light source change becomes large outdoors. Finally, the color evaluation value r is stored as the color evaluation value r '(S5) to prepare for the next input of the color evaluation value r. Since the gain control circuit 34 also inputs the color evaluation value b and operates in the same manner as the gain control circuit 33,
Detailed explanation is omitted.

The first embodiment of the present invention has been described above. As shown in FIG. 3, the indoor / outdoor discrimination circuit 23 uses the hall element 81 for detecting the aperture amount of the optical aperture mechanism 8 instead of the subtraction value M. When the detection output h is input, the threshold value ht is set, and the optical aperture mechanism 8 is opened and the detection output h is larger than the threshold value ht, the control signal S is set to the H level, and conversely the optical aperture mechanism 8 is determined to be indoors. When closed and the detection output h is smaller than the threshold value ht, it is possible to discriminate between indoors and outdoors by setting the control signal S to the L level as being outdoors.

Further, as shown in FIG. 4, the indoor / outdoor discrimination circuit 23
The luminance evaluation value y is input instead of the subtraction value M, the threshold value yt is set, and when the evaluation value y is smaller than the threshold value yt, it is determined that the vehicle is indoors, the control signal S is set to the H level, and conversely the evaluation value y is set.
When is larger than the threshold value yt, it is possible to discriminate between indoors and outdoors by setting the control signal S to the L level as being outdoors.

Further, as shown in FIG. 5, the indoor / outdoor discrimination circuit 23
When a control signal from the gain control circuits 33 and 34 is input in place of the subtraction value M and it is determined from the control signal that the color temperature (unit Kelvin: K) of the light source is around 5000K, the light source is sunlight. If it is present, it is possible to discriminate between indoor and outdoor where the control signal S is set to L level as being outdoors and the control signal S is H level as being otherwise indoors.

Further, as shown in FIG. 6, the indoor / outdoor discrimination circuit 23
In place of the subtracted value M, the control signals from the gain control circuits 33 and 34 and the detection output h of the Hall element 81 for detecting the aperture amount of the optical aperture mechanism 8 can be input to discriminate between indoors and outdoors. is there. That is, when the color temperature (unit Kelvin: K) of the light source is around 5000 K from the control signal, it is determined that the light source is sunlight, and the optical aperture mechanism 8 is opened and the detection output h is larger than the threshold value ht, In order to improve the response characteristic of the white balance adjusting operation, it is assumed that the control signal S is set to the L level as if it is outdoors, and otherwise the color temperature is erroneously determined due to the influence of the subject even indoors or outdoors. To H level.

Needless to say, the operation of each circuit described above can be processed by software using a microcomputer.

[0024]

According to the present invention, when the indoor / outdoor discrimination means discriminates that it is outdoors, the response characteristic of the white balance adjusting operation becomes slower than that of indoors. It is possible to perform stable white balance control that is not easily affected by panning and the color of the subject, and the effect is great.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the first to fifth embodiments of the present invention.

FIG. 3 is a circuit block diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit block diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit block diagram showing a fourth embodiment of the present invention.

FIG. 6 is a circuit block diagram showing a fifth embodiment of the present invention.

FIG. 7 is a circuit block diagram showing a conventional technique.

[Explanation of symbols]

 4 R amplification circuit 5 B amplification circuit 17, 18, 19 Integration circuit 23 Indoor / outdoor discrimination circuit 24 Subtractor 33, 34 Gain control circuit 8 Optical aperture mechanism 81 Hall element

Claims (4)

[Claims] 1. A white balance adjusting means for executing a white balance adjusting operation for controlling a gain of each color signal based on an imaged video signal, and a diaphragm for adjusting a luminance signal level in the imaged video signal to an optimum level. Exposure adjusting means for issuing an aperture control signal to the adjusting means to adjust the aperture amount of the aperture adjusting means;
A white balance adjustment characterized by comprising an indoor / outdoor discrimination means for discriminating an indoor photography state or an outdoor photography state from the aperture control signal, and changing the response characteristic of the white balance adjustment operation according to the output of the discrimination means. apparatus. 2. A white balance adjusting means for executing a white balance adjusting operation for controlling the gain of each color signal based on the picked-up image signal, and a diaphragm for adjusting a luminance signal level in the picked-up image signal to an optimum level. Exposure adjusting means for issuing an aperture control signal to the adjusting means to adjust the aperture amount of the aperture adjusting means;
An indoor / outdoor discrimination unit for discriminating an indoor photographing state or an outdoor photographing state from the diaphragm amount of the diaphragm adjusting unit is provided, and the response characteristic of the white balance adjusting operation is changed according to the output of the judging unit. White balance adjustment device. 3. A white balance adjusting means for executing a white balance adjusting operation for controlling the gain of each color signal based on the imaged video signal, and an indoor shooting state or an outdoor shooting state based on a luminance signal level in the imaged video signal. A white balance adjusting device, comprising: an indoor / outdoor discrimination means for discriminating between, and changing a response characteristic of the white balance adjustment operation according to an output of the discrimination means. 4. A white balance adjusting means for executing a white balance adjusting operation for controlling the gain of each color signal based on the picked-up video signal, and an indoor shooting state or an outdoor shooting state based on the color signal level in the picked-up video signal. A white balance adjusting device, comprising: an indoor / outdoor discrimination means for discriminating between, and changing a response characteristic of the white balance adjustment operation according to an output of the discrimination means.