JP2566389B2 - Automatic white balance adjustment device - Google Patents

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 automatically adjusting the white balance of a color video camera.

[0002]

2. Description of the Related Art FIG.
It is a block diagram which shows the structure of the conventional automatic white balance adjusting apparatus which applied the thought shown by FIG.

The automatic white balance adjusting device includes a lens (1)
The image pickup device (2) for photoelectrically converting the optical image incident from the lens (1) is arranged in the vicinity of the lens (1).

The image pickup device (2) is connected to a color separation circuit (3) for separating the signals photoelectrically converted by the image pickup device (2) into R, G, B color signals. The circuit (3) includes an Rch gain control circuit (4) and a Bch
The gain control circuit (5) and the process circuit (6) are connected to each other, and the Rch gain control circuit (4) and the Bch gain control circuit (5) are connected to the process circuit (6).

Further, an encoder circuit (7) and integrating circuits (8) and (9) are connected in parallel to the process circuit (6), and the integrating circuits (8) and (9) include an integrating circuit. A comparison circuit (1) that compares the level integrated by (8) and (9) with the reference level from the reference voltage generation circuit (15).
0) and (11) are connected.

A microcomputer (12) is connected to the comparison circuits (10) and (11), and a clock pulse is input to the microcomputer (12).

A D / A conversion circuit (13) for D / A converting the Rch output signal and a D / A conversion circuit (14) for D / A converting the Bch output signal are connected to the microcomputer (12). D / A conversion circuit (1
3) is connected to the Rch gain control circuit (4),
The D / A conversion circuit (14) is a Bch gain control circuit (5).
It is connected to the.

Next, the operation will be described.

The optical image incident from the lens (1) is photoelectrically converted by the image pickup device (2) and color-separated into three color signals of R, G and B by a color separation circuit (3).

Then, the gain control circuit (4) controls the gain of the R signal, and the gain control circuit (5) controls the gain of the B signal.

Then, the gain control circuits (4) and (5) control the gains of the R signal and the B signal to adjust the white balance.

On the other hand, the R-Y color difference signal and the BY color difference signal output from the process circuit (6) are integrated by the integrating circuits (8) and (9), and are compared with the reference voltage by the comparing circuits (10) and (11). Be compared.

Further, the microcomputer (12) is
The software has a reversible counting function, and the outputs of the comparison circuits (10) and (11) perform reversible counting in synchronization with the pulse.

Then, the reversible counting result is D / A converted by the D / A conversion circuits (13) and (14) to control the gains of the gain control circuits (4) and (5).

Then, the polarities of the comparison circuits (9) and (10), the direction of increase and decrease of the reversible counting function, the gain control circuit (4),
The gain control characteristic of (5) is RY when an achromatic color is captured.
A negative feedback loop is configured so that the signal and the BY signal are both 0.

It can be considered that the conditions are the same as in the case of imaging an achromatic color by integrating the entire surface by integrating circuits (8) and (9).

With the above operation, it is possible to automatically adjust the white balance even if the light source that illuminates the subject changes.

The operation of the microcomputer (12) at this time is shown in the flowchart of FIG. In addition, RchUD
C shows the reversible counting result of Rch, Bch UDC is Bc
The reversible counting result of h is shown.

The microcomputer (12) is RchO
UT, BchOUT, RchUDC and BchUDC are initialized (step S1), it is determined whether the output of the Rch comparison circuit (10) is at "H" level or "L" level (step S2), and the output of the Rch comparison circuit (10). If it is determined to be "L" level, RchUDC is incremented (step S3), and if it is determined that the output of the Rch comparison circuit (10) is "H" level, RchUDC is decremented (step S4).

The microcomputer (12)
Determines whether the output of the Bch comparison circuit (11) is the “H” level or the “L” level (step S5), and when the output of the Bch comparison circuit (11) is the “H” level, the BchUDC Is incremented (step S
6) When it is determined that the output of the Bch comparison circuit (10) is at the “L” level, BchUDC is decremented (step S7).

Then, the microcomputer (12)
Outputs RchOUT and BchOUT (step S
8) When a clock pulse is input (step S
9) and returns to step S2.

[0022]

Since the conventional automatic white balance adjusting device is constructed as described above, when there are many green objects on the entire screen, the gain of the R channel and the B
Both of the channel gains were large, and there was a problem that the white subject in the screen was colored magenta.

The present invention has been made to solve the above problems, and white balance adjustment is magenta,
It is an object of the present invention to obtain an automatic white balance adjusting device that is less likely to shift in an unnatural direction such as green.

[0024]

SUMMARY OF THE INVENTION An automatic white balance adjusting apparatus according to the present invention includes a lens, an image pickup device for photoelectrically converting an optical image incident from the lens, and R, G, A color separation circuit for separating the color signal into the B color signal, a gain control circuit for controlling the gain of the color signal separated by the color separation circuit, and an integration for integrating the output of the gain control circuit and the matrixed output of the luminance signal. Circuit,
A comparing circuit for comparing the level output by the integrating circuit with a reference level; and a reversible counting means connected to the output of the comparing circuit for performing reversible counting in synchronization with a pulse corresponding to the polarity of the comparing circuit,
A switch for selecting the first white balance adjustment mode or the second white balance adjustment mode, a trigger signal generation switch for generating a trigger signal, and a circuit for at least two channels from the comparison circuit to the gain control terminal are provided. There is. Then, a first closed region and a second closed region including the first closed region inside thereof are provided at coordinates determined by a combination of two or more reversible counting results corresponding to the number of channels. When the first white balance adjustment mode in which the white balance is automatically adjusted by following changes in the light source or the subject is selected by the selection switch, the reversible counting means determines the reversible counting result determined by the polarity of the output of the comparison circuit. When the destination of movement due to the increase or decrease of is above or outside the boundary of the first restriction region, the change of at least one reversible counting result is stopped, and the white balance is automatically adjusted by the trigger signal by the operation of the switch. A second white balance adjustment mode in which the adjustment state is stored and held until a trigger signal is applied from the trigger signal generation switch is selected by the selection switch. In this case, the reversible counting means stops the change of at least one reversible counting result when the movement destination due to the increase or decrease of the reversible counting result determined by the polarity of the output of the comparison circuit is at the boundary of the second restriction region or outside the boundary. It is characterized by that.

Therefore, according to the automatic white balance adjusting apparatus of the present invention, the optical image incident from the lens is photoelectrically converted by the image pickup device, and the signal photoelectrically converted by the image pickup device is converted into R, G and B signals by the color separation circuit. Separated into color signals, the gain of the color signals separated by the color separation circuit is controlled by the gain control circuit, and the output of this gain control circuit and the matrix output of the luminance signal are integrated by the integration circuit and integrated by the integration circuit. The level and the reference level are compared by the comparison circuit, and the reversible counting is performed by the reversible counting means in synchronization with the pulse corresponding to the polarity of the comparison circuit, and the number of circuits of at least two channels from the comparison circuit to the gain control terminal is supported. Done 2
In the coordinates determined by the combination of more than one reversible counting result,
A first closed area and a second closed area including the first closed area inside the first closed area are provided, and the white balance is automatically adjusted by tracking the change of the light source or the subject. When the mode is selected by the selection switch, the reversible counting means is at least when the movement destination due to the increase or decrease of the reversible counting result determined by the polarity of the output of the comparison circuit is on the boundary of the first restriction region or outside the boundary. A second white that stops the change of one reversible counting result, and automatically adjusts the white balance by a trigger signal by operating a switch, and stores the adjusted state until the next trigger signal is given from the trigger signal generation switch. When the balance adjustment mode is selected by the selection switch, the reversible counting means moves by increasing or decreasing the reversible counting result determined by the polarity of the output of the comparison circuit. If is at the boundary or outside the bounds of the second restriction region stops the change of at least one reversible counting result.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

(I) Invention of Claim 1 FIG. 1 is a block diagram showing a configuration of an automatic white balance adjusting apparatus according to the present invention.

As shown in FIG. 1, the automatic white balance adjusting device has a lens (1), and an image pickup device for photoelectrically converting an optical image incident from the lens (1) in the vicinity of the lens (1). (2) is arranged.

A color separation circuit (3) for separating the signals photoelectrically converted by the image pickup element (2) into color signals of R, G, B is connected to the image pickup element (2), and color separation is performed. The circuit (3) includes an Rch gain control circuit (4) and a Bch
The gain control circuit (5) and the process circuit (6) are connected to each other, and the Rch gain control circuit (4) and the Bch gain control circuit (5) are connected to the process circuit (6).

Further, an encoder circuit (7) and integrating circuits (8) and (9) are connected in parallel to the process circuit (6), and the integrating circuits (8) and (9) include an integrating circuit. A comparison circuit (1) that compares the level integrated by (8) and (9) with the reference level from the reference voltage generation circuit (15).
0) and (11) are connected.

A microcomputer (12) is connected to the comparison circuits (10) and (11), and a clock pulse is input to the microcomputer (12).

A D / A conversion circuit (13) for D / A converting the Rch output signal and a D / A conversion circuit (14) for D / A converting the Bch output signal are connected to the microcomputer (12). D / A conversion circuit (1
3) is connected to the Rch gain control circuit (4),
The D / A conversion circuit (14) is a Bch gain control circuit (5).
It is connected to the.

The automatic white balance adjusting device has a selection switch (25) for selecting the first white balance adjusting mode or the second white balance adjusting mode and a trigger signal generating switch (26) for generating a trigger signal. The switches (25) and (26) are connected to the microcomputer (12).

Next, the operation of this embodiment will be described with reference to FIGS.
This will be described along with the flowchart of

The microcomputer (12) is Rch
OUT, BchOUT, RchUDC and BchUDC
Set the initial value of (step S31), switch (2
By 5), the first white balance adjustment mode (hereinafter referred to as "tracking mode") that automatically adjusts the white balance by following changes in the light source or the subject, or the white balance is automatically adjusted by the trigger signal. Next, it is judged whether or not the second white balance adjustment mode (hereinafter, this mode is referred to as a "memory holding mode") in which the adjusted state is stored and held until a trigger signal is applied (step S3
2) If it is determined that the “tracking mode” is selected, the boundary is set to the first closed area (see FIG. 4) (step S
33).

Then, the microcomputer (12)
Performs a reversible counting process described later (step S34),
After that, RchOUT and BchOUT are output (step S35), and the process returns to step S32.

If it is determined in step S32 that the memory holding mode is selected, the boundary is set to the second closed area (see FIG. 4) (step S36), and the trigger signal is issued by the switch (26). It is determined whether or not (step S37).

When it is determined that the trigger signal is issued by the switch (26), the microcomputer (12) performs a reversible counting process described later (step S
38), it is determined whether or not convergence has occurred (step S39),
If it is determined that they have converged, RchOUT, BchOUT
Is output (step S40), and the process returns to step S32.

When it is determined in step S37 that the trigger signal has not been issued by the switch (26), the operations in step S40 and thereafter are performed.

If it is determined in step S39 that convergence does not occur, the process returns to step S38.

As described above, in the "tracking mode", the white balance is automatically adjusted by tracking the change of the light source or the object, and in the "memory holding mode", the white balance is adjusted by giving a trigger signal while the white object is imaged. Then, the adjusted value is stored and retained.

Here, the boundary area in FIG. 4 will be described.

FIG. 4 shows a two-dimensional plane by RchuDc, BchuDc or RchOUT, BchOUT, and it is classified into five patterns A, B, C, D, E in the flowchart of FIG. 3 according to the destination of the reversible counting result.

In the case of A, only RchOUT is changed.

In the case of B, RchOUT, BchOUT
Change both.

In the case of C, RchOUT, BchOUT
None of them are changed.

In the case of D, only BchOUT is changed.

In the case of E, RchOUT, BchOUT
Change both.

V by a light source of a general video camera device
The R and VB coordinates are in or around the closed area. (VR and VB are RchOUT and Bc, respectively.
It corresponds to hOUT or RchuDc, BchuDc. As described above, by changing Rch and BchOUT separately for A, B, C, D, and E, the coordinates of Rch and Bch do not move to the outside of the closed area.

Next, the reversible counting process of FIG. 3 will be described. In this process, the Rch reversible count result RchUDC by the output of the Rch comparison circuit and the Bch reversible count result BchUDC one clock before the coordinate (Rc
It is determined whether (hUDC, BchUDC) is on or outside the boundary of the restricted area defined by the main routine.

The microcomputer (12) is Rch
It is judged whether the output of the comparison circuit (10) is the "H" level or the "L" level (step S41), and the Rch comparison circuit (1
When it is determined that the output of 0) is at “L” level, Rc
Increment hUDC (step S42), Rc
When it is determined that the output of the h comparison circuit (10) is at the "H" level, RchUDC is decremented (step S43).

Then, the microcomputer (12)
Determines whether RchUDC and BchUDC are on the boundary or outside (step S44), and RchUDC,
When it is determined that the Bch UDC is not on or outside the boundary, it is determined whether the output of the Bch comparison circuit (11) is the "H" level or the "L" level (step S45), and the output of the Bch comparison circuit (11) is " If it is determined to be at the “H” level, BchUDC is incremented (step S4
6) When it is determined that the output of the Bch comparison circuit (10) is at the “L” level, BchUDC is decremented (step S47).

Then, the microcomputer (12)
Determines whether RchUDC and BchUDC are on the boundary or outside (step S48), and RchUDC,
When it is determined that BchUDC is not on or outside the boundary, RchUDC is set as RchOUT and BchOUT is set.
Be BchUDC, that is, A pattern (step S
49).

In step S48, RchU
When it is determined that DC and BchUDC are on the boundary or outside, RchUDC is set as RchOUT and BchUDC is set.
DC is set to BchOUT, that is, B pattern (step S50).

In step S44, Rc
If it is determined that hUDC and BchUDC are on the boundary or outside, the microcomputer (12)
It is determined whether the output of the comparison circuit (11) is the "H" level or the "L" level (step S51), and the Bch comparison circuit (1
When it is determined that the output of 1) is at the “H” level, Bc
Increment hUDC (step S52), Bc
When it is determined that the output of the h comparison circuit (10) is at the "L" level, BchUDC is decremented (step S53).

Then, the microcomputer (12)
Determines whether RchUDC and BchUDC are on the boundary or outside (step S54), and RchUDC,
When it is determined that BchUDC is on or outside the boundary, it is determined whether RchOUT, BchUDC is on or outside the boundary (step S55), and RchOUT,
When it is determined that the BchUDC is on the boundary or outside, the RchOUT is set to the RchUDC, and the BchOU is set.
Let T be BchUDC, that is, the C pattern (step S56).

When it is determined that RchOUT and BchUDC are not on or outside the boundary, RchOUT is set to R
chUDC and BchUDC is BchOUT, that is, D
The pattern is set (step S57).

In step S54, RchU
When it is determined that DC and BchUDC are not on the boundary or outside, RchUDC is set as RchOUT and BchU is set.
DCBchOUT is set to BchOUT, that is, E pattern (step S58).

When a clock pulse is input (step S59), the above operation is repeated.

In the above embodiment, the case where the reversible counting function and the region limiting function are realized by the microcomputer is shown, but the present invention is not limited to this, and may be realized by hardware using a reversible counting circuit or the like. . Further, other software may be used as long as the software does not go out of the closed area.

Further, in the above embodiment, the area surrounded by the six straight lines is shown, but the shape of the closed area may be, for example, a parallelogram, a circle, an ellipse, etc. The shape of the open area and the second closed area may be different from each other.

[0062]

As described above, according to the present invention, when the first white balance adjustment mode for automatically adjusting the white balance by following the change of the light source or the subject is selected, the comparison circuit If the destination of movement due to the increase or decrease of the reversible count result determined by the polarity of the output is on or outside the boundary of the first restriction area, at least one change of the reversible count result is stopped, and automatically by a trigger signal by operating the switch. When the second white balance adjustment mode in which the white balance is adjusted dynamically and the adjustment state is stored and held until the trigger signal is given from the trigger signal generation switch next, the reversible counting result determined by the polarity of the output of the comparison circuit is selected. When the movement destination due to the increase or decrease of is outside or at the boundary of the second restricted area, it is possible to stop the change of at least one reversible counting result. Since the coordinates determined by the counting result are not moved out of the closed area corresponding to the white balance adjustment mode, the white balance that deteriorates the image quality remarkably visually is limited only in the area where the RchOUT and BchOUT coordinates exist. It is possible to reduce the deviation of adjustment in the magenta and green directions.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an automatic white balance adjusting apparatus according to the present invention.

FIG. 2 is a flowchart showing the operation of the device of the present invention.

FIG. 3 is a flowchart showing the operation of the device of the present invention.

FIG. 4 is an operation explanatory diagram of the apparatus of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional automatic white balance adjusting device.

FIG. 6 is a flowchart showing an operation of a conventional automatic white balance adjusting device.

[Explanation of symbols]

1 lens, 2 image sensor, 3 color separation circuit, 4 Rc
h gain control circuit, 5Bch gain control circuit, 8, 9
Integration circuit, 10, 11 comparison circuit, 12 microcomputer, 25 selection switch, 26 trigger signal generation switch.

Claims (1)

(57) [Claims] 1. A lens, an image pickup device for photoelectrically converting an optical image incident from the lens, and a color separation circuit for separating signals photoelectrically converted by the image pickup device into R, G, B color signals.
A gain control circuit for controlling the gain of the color signal separated by the color separation circuit, an integrating circuit for integrating the output of this gain control circuit and the matrix output of the luminance signal, and the level output by the integrating circuit and the reference level. A comparison circuit for comparing
A reversible counting means connected to the output of the comparison circuit and performing reversible counting in synchronization with a pulse corresponding to the polarity of the comparison circuit; and an automatic white balance adjustment for white balance adjustment based on the result of the reversible counting by the reversible counting means. In the device, a selection switch for selecting the first white balance adjustment mode or the second white balance adjustment mode, a trigger signal generation switch for generating a trigger signal, and at least two channels from the comparison circuit to the gain control terminal. A second closed region including a first closed region and a first closed region inside at a coordinate determined by a combination of two or more reversible counting results corresponding to the number of channels. Select the first white balance adjustment mode by the selection switch, which has a separate area and automatically adjusts the white balance by following changes in the light source or subject. When, the reversible counting means,
When the destination of the reversible counting result, which is determined by the polarity of the output of the comparator circuit, increases or decreases and is on the boundary of the first restriction region or outside the boundary, at least one change of the reversible counting result is stopped and a switch operation is performed. The reversible counting means when the second white balance adjustment mode in which the white balance is automatically adjusted by the trigger signal and the adjustment state is stored and held until the trigger signal is given from the trigger signal generation switch is selected by the selection switch. Is characterized in that the change of at least one reversible counting result is stopped when the movement destination due to the increase or decrease of the reversible counting result determined by the polarity of the output of the comparison circuit is at the boundary of the second restriction region or outside the boundary. Automatic white balance adjustment device.