JPH0468691A - Video camera - Google Patents

Abstract

PURPOSE:To photograph with color tone close to the human's sight by correcting the position of white balance setting so as to keep up the color temperature of nature light based on the season and time in photographing. CONSTITUTION:A correction value table 22 outputs a white balance setting position correction data according to the time information inputted from a counting time circuit 20, and the correction data is converted to analog correction signals CR/CB. These signals CR and CB have high levels in the morning and the evening, and are changed according to the time to reduce the level during day. Control voltages VRT and VBT added with these signals CR and CB are inputted to gain control circuits 4/5, the voltage VRT and VBT are increased respectively before correction in the morning and the evening as the voltage VRT is boosted, the gain is increased, and the voltage VBT is dropped, the gain is decreased in the circuit 5, so the white balance is set in the position shifted to a red side. On the other hand, the voltages VRT and VBT become a little bit smaller than the VR and VB, and the white balance is set in the position shifted to a blue side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] This invention relates to a white balance adjustment device for a video camera.

[Conventional technology]

FIG. 4 is a block circuit diagram showing a white balance adjustment circuit of a conventional video camera device disclosed in Japanese Utility Model Publication No. 41-16011, in which (1) is a lens, (2) is an image sensor, and (3)
) is a color separation circuit, (4) is an R channel gain control circuit, (5) is a B channel gain control circuit, (6) is a process circuit, (7) is a matrix circuit, (8) is an encoder circuit, ( 9) is the output terminal, (11) is the R sensor (a photoelectric conversion element that is mainly sensitive to red), and +12) is the G
Sensor (photoelectric conversion element mainly sensitive to green),
+131 is the B sensor (a photoelectric conversion element that is mainly sensitive to n colors), (14)115) is a division circuit, and the gain control circuits +41, +51 and division circuit f141115
+ constitutes a white balance adjustment circuit (I6).

Next, the operation will be explained. A light image incident from a lens (1) is photoelectrically converted by an image sensor (2), and color separated into three color signals (H, G, BO) by a color separation circuit (3). A gain control circuit (4) controls the gain of the R signal, and a gain control circuit (5) controls the gain of the B signal to adjust the white balance of the captured image.

In addition, the R sensor (II), the G sensor (12), and the B sensor (13) generate output signals Rs, Gs, and Bs proportional to the R component, G component, and B component of the incident light. The division circuit (14) outputs the ratio as/R, (=VLl) of the G component and the R component that does not depend on the light 5 of the incident light, and the division circuit (+5)
outputs the ratio B, /Gs (=VI) of the B component and the G component.The gain control circuit (4) increases its gain as the control voltage VR increases, and the gain control circuit (5)
is configured to have a control characteristic in which the gain decreases as the control voltage ■8 increases, and in the case of a light source with a low color temperature, that is, a light source with a large R component and a small B component relative to the G component, the control The value of the voltages V, , V, is lower than when the color temperature is high. Therefore, when the color temperature of the light source is low, the gain of the R channel gain control circuit (4) is small and the gain of the B channel gain control circuit (5) is large.

Conversely, in the case of a light source with a high density of one color, that is, a light source with less R component and more B component than G component, the gain of the R channel gain control circuit (4) increases, and the gain of the B channel gain control circuit increases. The gain of (5) becomes smaller.

In this way, the R component and G component included in the light source.

By automatically controlling the gain of the channel gain control circuit (4) and the gain of the B channel gain control circuit (5) in response to changes in the B component, that is, color temperature,
Adjusting the white balance.

Fig. 5 is a block circuit diagram of the white balance circuit shown in Japanese Patent Application Laid-Open No. 63-242090. B signal and G signal 7 from separation circuit (3) Integrating circuit that integrates B signal, (17), (+8)
, (+91 is provided, and the integral signal is used as the control signal V,,V
, and control the gain of the gain control circuits +4) and +5), and the white balance can be adjusted using the same operating principle as the conventional example shown in FIG.

[Problems to be Solved by the Invention] Since the conventional white balance device for a video camera is configured as described above, the white balance is always adjusted to a constant value even if the color temperature of the light source changes. For this reason, even if an obviously white subject, such as a sunset, appears reddish to the human eye, the subject is captured as white, resulting in a rather unnatural captured image.

This invention was made to solve the above problems, and provides a video camera that can adjust the white balance to produce a more natural captured image that is closer to human visual perception when the color temperature of the light source changes. The purpose is to obtain a white balance device.

[Means to solve the problem]

The white balance device according to the present invention includes a means for obtaining correction data corresponding to the color temperature of natural light at the time of shooting, and a means for obtaining correction data corresponding to the color temperature of natural light at the time of shooting, and a means for obtaining correction data corresponding to the color temperature of natural light at the time of shooting, and a white balance setting position of one step of white balance adjustment based on the correction data. and means for correcting it so that it approaches .

[Function] In the present invention, the L stage for obtaining correction data outputs correction data corresponding to the color temperature of natural light at the time of photographing, and the means for correcting the white balance setting position is a white balance adjusting means based on the correction data. Change the white balance setting so that the white balance setting position approaches the color sense of natural light at the time of shooting (for example, at dusk (sunset), move the mill balance toward red).

[Embodiment J Figure 1 is a block circuit diagram showing the configuration of this invention.
0) is a timekeeping circuit that generates time information, and (21) is a timekeeping circuit that corrects the white balance setting position of the white balance adjustment circuit (16), that is, the color temperature, according to the time information obtained from the timekeeping circuit (20). This is a self-balance setting position correction circuit.

In Figure 2, the white balance adjustment circuit (16) has the same configuration as the conventional example shown in Figure 4, and the white balance setting position correction circuit (16) has the same configuration as the conventional example shown in Figure 4.
21) is a concrete example block circuit.
22) is a correction (10) that outputs data for correcting the white balance setting position according to the output information of the timekeeping circuit (20).
Table (23), +241 is the correction value table (2
A D/A converter that converts the supplementary IF data output from 2) into an analog signal, and (25) adds the output C8 of the D/A converter (23) and the output VR of the divider circuit (14). The adder, same < +261, is an adder that adds the output Cs of the D/A converter (24) and the output V of the division circuit (15), and the output VR7 of the adder (25) is added to the output Cs of the D/A converter (24) and the output V of the divider circuit (15).
), the output VBT of the adder (5) is controlled by the gain control circuit (5).
are respectively input as gain control No. 15.

Next, the operation will be explained.

The correction amount table (22) outputs white balance setting position correction data according to the time information input from the time measurement circuit (20), and the correction data is sent to the D/A converter (231,
(It is converted into an analog correction signal C8°C8 by 241. For example, as shown in Fig. 3, the correction signals CR and Ca change according to the time of day so that the level is high in the morning and evening, and the level is low during the day. Adder (251, (2
61 converts the correction signals C, ,C, into control voltages V, ,V,
Add to each. The control voltage V n7. to which the correction signals C, , C, are added. V BT is gain control circuit (4)
, (5) 1m is input and its gain is changed. The gain of the gain control circuit (4) increases as the control voltage VRT increases, and the gain of the gain control circuit (5) decreases as the control voltage VRT increases. Pc V RT, V at
are larger than before correction, the gain of the R channel gain control circuit (4) is larger, the gain of the B channel gain control circuit (5) is smaller, and the white balance is at a position slightly deviated from the photometry. Set.

On the other hand, during the day, the control voltage VRa, V, ? is slightly smaller than VRlVll, and the white balance is set to a position slightly shifted to the front. In this way, the white balance setting position is corrected depending on the time. As a result, the color tone of the photographed image becomes an image with a color tone close to the visual sense.

In the above embodiment, the two correction words cR08 are changed in the same pattern, but it is not necessarily necessary to change them in the same pattern, and in order to change the white balance setting more effectively, they can be changed in different patterns. Of course it is also good.

Further, - in the above embodiment, the timekeeping circuit (20) is provided to obtain time information, but if the video camera is provided with a timekeeping means for performing superimposition, the timekeeping circuit (20) is provided. It goes without saying that you can also use side means.

Further, the correction value table (22) can also be realized by a microcomputer, and a microcomputer with a built-in D/A converter is more suitable.

In addition, in the above embodiment, the white balance setting position was corrected only for the time of -day, but by correcting the white balance setting position not only for the time but also for the date information, it is possible to correct changes in sunlight hours. It is clear that more accurate white balance correction can be made in response to

In addition, if the white balance adjustment circuit (16) is provided with means for switching between artificial light and sunlight, the white balance position correction circuit (21) is activated only when sunlight is selected. If configured, misuse can be avoided.

Furthermore, in the above embodiment, the white balance adjustment circuit (16)
Although the circuit shown in FIG. 4 was used in this invention, it is clear that the same effect can be obtained by using the white balance adjustment circuit shown in FIG. It is not limited to.

[Effects of the Invention] As described above, according to the present invention, the white balance setting position of the white balance adjustment circuit can be brought closer to human visual perception so as to follow the change in color temperature of natural light based on the season and time at the time of shooting. Since the video camera is equipped with a correction means, it is possible to obtain a video camera that can take pictures with a color tone close to the human visual sense.

[Brief explanation of the drawing]

1.X is a block circuit diagram showing the configuration of this invention, FIG. 2 is a block circuit diagram of an embodiment of this invention, FIG. 3 is a diagram showing changes in the correction signal with respect to time in this embodiment, and FIG. 4 and FIG. 5 are block circuit diagrams of different conventional white balance adjustment devices for video cameras. (15)...White balance adjustment circuit, (20)...
Time measurement circuit, (21)... White balance setting position correction circuit, (22)... Correction value table, (23), (2
41・−[)/p, converter. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A white balance adjustment means, a means for obtaining correction data corresponding to the color temperature of natural light at the time of shooting, and based on the correction data, the white balance setting position of the white balance adjustment means is adjusted to the visual perception due to the natural light at the time of shooting. and a means for correcting the video camera to approach the video camera.