JPH04252588A - White balance adjustment device - Google Patents

Abstract

PURPOSE:To offer the white balance adjustment device able to a just white balance following a change in an incident luminous quantity at image pickup. CONSTITUTION:The white balance adjustment device consists of a white balance signal processing section 1, a Hall element 5 detecting an aperture of an iris 4 and a microcomputer 2 giving a white balance control signal WB being a white balance adjustment quantity to the signal processing section 1. The microcomputer 2 includes a CPU 21 and a memory 22 to detect a change in the aperture of the iris 4 based on an iris signal S1 given from the Hall element 5 so as to output the signal WB at a speed in following to the change in the incident luminous quantity.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a white balance adjustment device, and in particular, a white balance adjustment that changes the operating speed of white balance adjustment according to the aperture value at the time of imaging of an imaging device in which the adjustment device is installed. Regarding equipment.

0002

2. Description of the Related Art A color imaging device has a white balance adjustment device for displaying an object on a screen in the same color as seen by the human eye.

[0003] In a color imaging device, it is necessary to automatically add corrections to the color information obtained by imaging a subject in accordance with the imaging conditions (such as illumination) at that time. A white balance adjustment device is provided for this purpose.

A conventional white balance adjustment device obtains a color signal of an image of a subject as an output voltage signal from an image sensor via an optical system. This output voltage signal is
The primary color signals R, G and B can be obtained. When the white balance is properly achieved, the signals R, G and B
It is known that each voltage level of is equal. Therefore, by adjusting the gain of each signal so that the relationship between the three primary color signals is (R=G=B), a correct white balance can always be obtained.

A conventional white balance adjustment device inputs each signal R, G, and B, determines the amount of gain adjustment accordingly, and adjusts the level of each signal so that R=G=B.

The conventional white balance adjustment device described above inputs the primary color signals R, G, and B, determines a white balance adjustment amount for the voltage level, and performs gain adjustment of the primary color signals R, G, and B using this adjustment amount. A kind of closed loop is constructed in which white balance is adjusted during image capture.

[0007]

The adjustment speed of the above-mentioned white balance adjustment device is a fixed value that is uniquely determined by a time constant caused by a capacitor, a resistor, etc. installed in the device. Alternatively, when the device is powered on, an initial predetermined voltage for adjustment is applied,
The white balance adjustment operation was set to start quickly, and then the white balance adjustment was performed by repeating the above-mentioned closed loop at a constant operation speed.

[0008] Generally, an image pickup device is provided with an iris diaphragm so that the amount of light incident on the surface of the image pickup device is maintained at an appropriate value. The iris diaphragm limits the amount of incident light by opening and closing concentrically. The opening/closing operation is automatically controlled so that the luminance signal component of the video signal obtained through the image sensor maintains a predetermined appropriate value. Therefore, indoors where the illumination light is relatively dark, the iris diaphragm is set in the open direction, but conversely, outdoors where the illumination light from sunlight is extremely bright, the iris diaphragm is set in the closed direction to reduce the amount of incident light. be done.

By the way, in the imaging operation of such an imaging device, when panning from indoors to outdoors, the state of the iris diaphragm largely changes to the closed direction. Conversely, when panning from outdoors to indoors, the state of the iris diaphragm changes greatly toward the open direction. In other words, when the photographing conditions change significantly and rapidly, the iris aperture value also changes rapidly and significantly. In this way, when the photographing conditions suddenly change, the amount of incident light changes suddenly following the displacement of the iris diaphragm, so the color temperature also changes suddenly, and the signal levels of the three primary color signals also change significantly. Therefore, in such a case, the white balance of the video signal obtained from the three primary color signals will be significantly disrupted. this,
If an attempt was made to restore the white balance using the above-described conventional white balance adjustment having a fixed operating speed, there was a problem that it would take too much time for the white balance to be restored to normal, making it impractical. Therefore, in order to solve this problem, it is considered that the operation speed of white balance adjustment should be set to a high speed so that the adjustment operation can quickly follow the sudden and large change in the imaging conditions. However, while the white balance adjustment speed is capable of following sudden and large changes in the photographing conditions, on the other hand, the adjustment speed is too fast during normal photographing operations, making it impossible to obtain stable white balance adjustment. In other words, for example, if the above-mentioned high adjustment speed is set and the magnification of the zoom lens of the imaging device is set to the wide side, it is assumed that objects frequently move in and out of the field of view. In this case, white balance adjustment works effectively based on the color of this object that is frequently coming and going. Therefore, the white balance of the entire video signal remains unstable no matter how long it lasts, and the solution described above has not been a fundamental solution.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a white balance adjustment device that can adjust the white balance by following the change in the amount of incident light during imaging.

[0011]

[Means for Solving the Problems] A white balance adjustment device according to the present invention includes an adjustment means for sequentially inputting a video signal obtained by imaging and adjusting the white balance of the video signal accordingly; The aperture value detection means detects the aperture value, and the control means variably controls the adjustment speed of the adjustment means in response to the aperture value detected by the aperture value detection means.

[0012] Furthermore, in the white balance adjustment device according to the present invention, in the device as described above, the control means comprises:
Further, a displacement calculating means for calculating a displacement of the aperture value detected by the aperture value detecting means, a determining means for determining that the aperture value displacement calculated by the displacement calculating means is larger than a predetermined value, and a discriminating means for determining that the aperture value displacement calculated by the displacement calculating means is larger than a predetermined value. A speed setting means for setting the speed of the white balance adjustment to a high speed in response to a determination result of the means, and a driving means for driving the adjustment means according to the speed set by the speed setting means. You can do it like this.

[0013]

[Operation] Since the white balance adjustment device according to the present invention is constructed as described above, the control means can variably control the adjustment speed of the adjustment means in response to the aperture value detected by the aperture value detection means. Therefore, when a large change in the aperture value is detected, the adjustment speed of the adjustment means for adjusting the white balance is set to a high speed, so that the white balance adjustment operation can follow when the shooting conditions change drastically and suddenly. performance is improved. That is, the displacement of the aperture value detected by the aperture value detection means is calculated by the displacement calculation means, and when it is determined that this calculated displacement is larger than a predetermined value, the speed setting means sets the adjustment speed of the adjustment means to a high speed. Since the driving means drives the adjustment means according to the set speed, the white balance adjustment speed is adjusted to a normal white balance by following the displacement of the aperture value of the imaging device in which the white balance adjustment device is installed. The white balance can be variably adjusted so that the white balance can follow changes in imaging conditions in real time.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing the functional configuration of a white balance adjustment device installed in a video camera according to an embodiment of the present invention.

The illustrated white balance adjustment device is as follows:
A signal processing unit 1, a microcomputer 2, a D/A converter 3, and an iris diaphragm which are given an input video signal IN, perform various signal processing such as white balance adjustment on the signal IN, and output an output video signal OUT. 4 and a Hall element 5 provided in association with the iris diaphragm 4.

The iris diaphragm 4 is provided to limit the amount of light incident on an optical system (not shown), and has a structure in which the aperture changes continuously on concentric circles. The iris diaphragm 4 is provided with a magnet (not shown), and the intensity of the magnetic field generated therein changes depending on the extent to which the iris diaphragm 4 is opened or closed. The magnetic field strength, which changes depending on the degree of opening and closing of the iris 4, is detected by a Hall element 5 provided near the iris 4,
The Hall element 5 generates a Hall voltage due to the so-called Hall effect. Since this Hall voltage is an output signal of the Hall element 5 which operates as a magnetic sensor, it is possible to detect the degree of opening and closing of the iris diaphragm 4 by detecting the Hall voltage. The Hall voltage generated by the Hall element 5 is given to the microcomputer 2 as an aperture value signal S1 having a voltage level.

The microcomputer 2 includes a CPU 21
, a memory 22 and an A/D converter 23, and inputs the aperture value signal S1, the vertical blanking pulse VD extracted from the input video signal IN, and the color signals R, G, and B given from the signal processing section 1. Accordingly, it operates to provide a white balance control signal WB to the signal processing section 1 via the D/A converter 3.

The data stored in the memory 22 is:
Data is updated by reading and writing by the CPU 21. The store data includes setting value M1, aperture value S2, and flag F1.
, VD count value V1, and predetermined time value T1.

The set value M1 is a value set in advance as a reference value for determining the magnitude of displacement of the iris diaphragm 4. Further, the aperture value S2 is the previously detected aperture value that should be stored in advance in order to calculate the displacement of the aperture in the iris aperture 4. In other words, CPU2
1 inputs the aperture value signal S1 as a digital signal via the A/D converter 23, converts it into an aperture value according to a predetermined calculation, and stores it in the memory 22 as an aperture value S2, so that it is always the same as the previous one. The aperture value is stored in the memory 22 as the aperture value S2.

Note that the standard aperture value is set as the initial value of this aperture value S2. Further, the flag F1 is a value that specifies the current operating speed mode for white balance adjustment. That is, if the CPU 21 accesses the memory 22 and reads that the flag F1 is set, the white balance adjustment device quickly determines that the white balance adjustment is being performed. Conversely, if it is read that the flag F1 is in the reset state, the white balance adjustment device determines that the white balance adjustment is being performed at the normal speed. Note that the initial state of the flag F1 is a reset state.

Further, the VD count value V1 is a value that determines the adjustment speed of white balance adjustment of the white balance adjustment device, and is set by the CPU 21.

The value of the VD count value V1 is set as follows. First, the value 1 is set as an initial value. Thereafter, when an imaging operation is performed in the video camera equipped with the white balance adjustment device, white balance adjustment is started in response to the input of the first vertical blanking pulse VD. Then, at the start of the imaging operation, the CPU 21 inputs the aperture value signal S1, and accordingly calculates the displacement of the aperture value based on the aperture value S2 stored in the memory 22. At this time, the CPU 21 sets the calculated displacement to a set value M stored in advance in the memory 22.
If it is determined that it is smaller than 1, the VD count value V1 is set to a value of, for example, 15 to 20, and conversely, if it is determined that it is larger, the VD count value V1 is set to, for example, a value of 4.
Set. In other words, if a large change in the aperture value of the iris aperture 4 is not detected during the imaging operation, the vertical blanking pulse VD is 15 or 2 at the VD count value V1.
A normal speed is set such that the white balance adjustment operation is performed every time the number of inputs is zero. Conversely, if a large change in the aperture value of the iris diaphragm 4 is detected during the imaging operation, the VD count value V1 is set such that a white balance adjustment operation is performed every four times the vertical blanking pulse VD is input. A high speed is set. In this way, the CPU 21 calculates the displacement of the aperture value according to the aperture value signal S1 given during imaging, and sets a value corresponding to the calculated displacement to the VD count value V1, thereby tracking the displacement of the aperture value. Processed to obtain white balance adjustment speed.

Further, the predetermined time value T1 defines a time period during which the high-speed white balance adjustment operation is to be continued, and is set to, for example, one second. In other words, even if the white balance is significantly disrupted, the high-speed white balance adjustment will continue for one second until a sufficiently normal white balance is restored.

The signal processing section 1 receives an input video signal IN based on the white balance control signal WB.
Adjust the white balance. This white balance adjustment is performed on the signal level of each of the color signals R, G, and B (R=G=B
), and the video signal thus adjusted is subjected to various other processes and then given to subsequent circuits as an output video signal OUT. Further, the color signals R, G, and B included in the adjusted video signal are separated from the video signal and given to the microcomputer 2 again.

As described above, the microcomputer 2 inputs the color signals R, G, and B included in the white balance-adjusted video signal from the signal processing section 1, and accordingly generates the white balance control signal, which is the amount of white balance adjustment. W
B is generated and given to the signal processing unit 1, and the color signals R, G and B adjusted by this signal WB are input again. In this way, a control loop is configured for white balance adjustment.

FIGS. 2(a) and 2(b) are process flow diagrams showing a white balance adjustment operation in a white balance adjustment apparatus according to an embodiment of the present invention.

The illustrated processing flow is stored in advance as a program in the memory 22 of the microcomputer 2 and executed under the control of the CPU 21. Further, this processing flow is an interrupt process that is started in accordance with the interrupt control of the CPU 21. In other words, the CPU 21 is constantly inputting the vertical blanking pulse VD obtained from the input video signal IN during imaging, and in response to the input of the pulse VD, starts executing this interrupt process and adjusts the white balance. ing.

FIG. 2(a) shows an outline of the interrupt processing, and FIG. 2(b) shows details of the interrupt processing.

Next, the white balance adjustment operation under the control of the CPU 21 will be explained with reference to the schematic processing flow shown in FIG. 2(a).

First, when the CPU 21 starts executing the interrupt process by inputting the vertical blanking pulse VD, first in step S1 (abbreviated as S1 in the figure), the value of the VD count value V1 is set to (V1=V1-1). ), and whether or not the result of the calculation is 0 is determined in the next step S2. At this time, unless (V1=0), CP
U21 exits from the interrupt process and returns to the process that was being executed before the interrupt, but if (V1=0) is established, the white balance adjustment operation as described above is performed in the next process of step S3.

After the white balance adjustment operation in step S3, the CPU 21 reads the aperture value signal S1 from the Hall element 5 in the process of step S20, and determines the white balance adjustment speed based on this signal S1 in the process of step 30. Set count value V1. Thereafter, the process returns to the process that was being executed before the interrupt process.

The above is the approximate white balance adjustment operation by the CPU 21. In this way, the white balance adjustment operation is performed at a speed according to the VD count value V1 (a value that determines the white balance adjustment speed) determined in response to the aperture value signal S1.

The processing flow shown in FIG. 2(b) is a more detailed version of the above-mentioned general processing flow.

In the processing flow shown in FIG. 2(b), the CPU 21
When starting execution of the interrupt process due to the input of the vertical blanking pulse VD, the process of step S1 and step S2 as described above is executed. If (V1=0) is established in the process of step S2, white balance adjustment is performed in step S3.

After the white balance adjustment operation, the CPU
21 performs high-speed white balance adjustment for a predetermined period of time if it determines that the white balance adjustment is currently in high-speed operation, but if it determines that the current high-speed operation is not currently in progress, the current white balance adjustment is The displacement of the aperture value of the iris diaphragm 4 is calculated, and processing is performed to determine whether to set the white balance adjustment speed to the high speed side or to the normal speed according to the calculated value. The details will be explained below.

When a video camera equipped with a white balance adjustment device starts an imaging operation, an input video signal IN is applied to the signal processing section 1, and a vertical blanking pulse VD is applied to the CPU 21. C.P.
U21 starts execution of the interrupt process shown in FIG. 2(b) by interrupt control in response to the input of the vertical blanking pulse VD.

It is assumed that initial values are set in advance for each of the set value M1 to the predetermined time value T1 in the memory 22.

First, in step S1, the CPU 21
accesses the memory 22 and stores the V stored in advance.
The D count value V1 is read and decremented as (V1=V1-1) to update the data. In the subsequent step S2, the updated VD count value V
For a value of 1, it is determined whether (V1=0). (V1
=0) If not established, the CPU 21 exits from this interrupt process and returns to the process that was being executed before the interrupt.

Conversely, if (V1=0) holds true, the CPU
21 moves to the white balance adjustment process from the next step S3, and after the adjustment, the adjustment speed is set in accordance with the current aperture value.

First, in the process of step S3, a white balance adjustment operation is performed. Specifically, each component of the three primary color signals R, G, and B of the input video signal IN provided to the signal processing section 1 is provided to the CPU 21 via the A/D converter 23. The CPU 21 receives the signal R,
Each of the G and B components is input as a digital signal, and a digital signal that satisfies (R=G=B) for each signal component is passed through the D/A converter 3 to the signal processing unit 1 as a white balance control signal WB. give to The control signal WB has a DC voltage level and acts as a gain adjustment amount for each of the three primary color signals R, G, and B in the signal processing section 1. As a result, the output video signal OUT with white balance adjusted (R=G=B) for each signal component is given to the circuits from the next stage onward, and the three primary color signals R, G, and B are again sent to the microcomputer 2. given to.

After the above-described white balance adjustment operation, the CPU 21 uses the memory 22 in the next step S4.
The flag F1 stored in is read out, and it is determined whether or not the white balance adjustment operation is in high-speed operation. If the flag F1 is in a set state, high-speed operation is in progress, and the process branches to steps after step S8, which will be described later. However, if flag F1 is in a reset state, then it is in normal speed operation, so the next step after step S5 is executed. Branch to processing.

In the process of step S5, the CPU 21
determines the magnitude of the current displacement of the iris diaphragm 4. That is, the CPU 21 sends the aperture value signal S1 to the A/D converter 23.
The aperture value is input as a digital signal via a predetermined conversion process. Then, the difference between this converted current aperture value and the previous aperture value S2 stored in the memory 22 is calculated, and whether the calculated value is larger than the set value M1 also stored in the memory 22 is determined. Determine whether In other words, it is determined whether or not the aperture of the iris 4 has changed significantly. Along with this determination, the aperture value converted from the current aperture value signal S1 is stored in the memory 2.
It is stored at the aperture value S2 of 2. At this time, if it is determined that the diaphragm displacement is large, the processes from step S8 to be described later are executed, but if it is determined that the diaphragm displacement is small, the processes from the next step S6 are executed.

In the process of step S6, the CPU 21
In response to the small displacement of the aperture amount, the VD count value V1 is set to one of the values 15 to 20 so that the white balance adjustment is performed at the normal speed. Then, in the next step S7, the flag F1 in the memory 22 is reset, and the predetermined time value T1 is also set to 1 second to perform the reset process. Thereafter, the CPU 21 returns to the process that was being executed before executing this interrupt process.

As described above, if the aperture of the iris 4 does not change significantly during imaging, there will be no sudden change in the imaging conditions and the white balance of the video signal will not be significantly disrupted. White balance can be adjusted adequately even at operating speeds. That is, it is sufficient to perform the white balance adjustment every time the vertical blanking pulse VD is applied any number of times from 15 to 20 times.

In the process of step S4 or step S5, the CPU 21 determines that the flag F1 is set and the current white balance adjustment is in high-speed operation, or that the aperture value of the iris diaphragm 4 suddenly changes greatly during imaging. If it is determined that this has occurred, the process proceeds to step S8 and subsequent steps.

That is, when the displacement of the aperture value of the iris diaphragm 4 suddenly becomes large, it is determined that the video camera has entered an imaging state in which the amount of light incident on the video camera suddenly changes. Therefore, the white balance will be significantly disrupted, so it is necessary to speed up the white balance adjustment operation to quickly restore the white balance to normal. To this end, in the process of step S8, if high-speed operation is already in progress, it is determined whether this high-speed white balance adjustment has already been continued for a period defined by a predetermined time value T1. At this time, if it is determined that high-speed white balance adjustment has already been performed for a predetermined period of time, it is determined that the white balance has been sufficiently recovered, and the process proceeds to step S6 described above to restore the normal white balance. Move to adjustment operation.

On the other hand, if it is within the predetermined time, it is determined that the white balance that has collapsed due to the sudden change in the aperture value has not yet been properly restored, and the VD count value V1 is quickly restored in the process of the next step S9. Value 4 for operation
is set, and in the next step S10, the flag F1 is set to the set state. This specifies that white balance adjustment is currently in the high-speed operation mode. Thereafter, the CPU 21 exits from this interrupt processing and returns to the processing before execution of the interrupt processing.

As described above, white balance adjustment is performed every four times when the vertical blanking pulse VD is input for a certain period of time after the aperture value of the iris diaphragm 4 changes significantly due to a sudden change in the imaging conditions. The camera is set to a high-speed mode that quickly restores the white balance to its normal state. After that, the normal white balance adjustment speed is resumed to maintain the restored normal white balance.

As described above, according to this embodiment, if the video camera is used to take pictures under one light source from beginning to end, a stable white balance adjustment operation can be obtained. Additionally, if there is a major change in the light source, such as when panning from indoors to outdoors during shooting, high-speed white balance adjustment is performed to quickly restore normal white balance.

Note that the setting value M stored in the memory 22
1. The values of the VD count value V1 and the predetermined time value T1 are not limited to the values defined in this embodiment.

[0052]

Effects of the Invention The white balance adjustment device according to the present invention variably controls the white balance adjustment speed in response to the aperture value at the time of imaging detected by the aperture value detection means. This has the effect of being able to adjust the white balance in real time by following changes.

Further, the displacement calculating means calculates the displacement of the aperture value detected by the aperture value detecting means, and when it is determined that the calculated displacement is larger than a predetermined value, the photographing conditions have changed significantly due to panning or tilting. Since it is determined that the speed setting means operates so that the white balance adjustment is performed at high speed, there is an effect that the followability of the white balance to large and rapid changes in photographing conditions is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the functional configuration of a white balance adjustment device installed in a video camera according to an embodiment of the present invention.

FIGS. 2(a) and 2(b) are process flow diagrams showing a white balance adjustment operation in a white balance adjustment apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 Signal processing section 2 Microcomputer 4 Iris aperture 5 Hall element 21 CPU 22 Memory M1 setting value S2 Aperture value F1 flag V1 VD count value T1 Predetermined time value R, G, B color signal WB White balance control signal S1 Aperture value signal VD Vertical blanking pulse In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. Adjusting means for sequentially inputting a video signal obtained by imaging and adjusting the white balance of the video signal accordingly; aperture value detection means for detecting an aperture value at the time of imaging; A white balance adjustment device comprising: a control means for variably controlling the adjustment speed of the adjustment means in response to the aperture value detected by the detection means. 2. The control means includes a displacement calculation means for calculating a displacement of the aperture value detected by the aperture value detection means, and the aperture value displacement calculated by the displacement calculation means is larger than a predetermined value. a speed setting means for setting the speed of the white balance adjustment to a high speed in response to the determination result of the determining means; and a speed setting means for driving the adjusting means according to the speed set by the speed setting means. Claim 1 further comprising a driving means for
White balance adjustment device as described.