JPH07154814A - White balance adjusting device - Google Patents

Abstract

PURPOSE:To facilitate the adjustment corresponding to a stroboscope photographing by switching a white balance object area from all the areas of the screen to a partial area and performing the white balance adjusting operation based on the video signal depending on this switched area. CONSTITUTION:When the area designation signal from an area setting switch 21 designating a white balance(WB) object area is inputted in a CPU 7, the CPU 7 transmits WB object area display information to a character mix circuit 22. In the circuit 22, display information is mixed with the image information from a camera process processing part 5 and a monitor display is performed for the mixed information in an EVF 23. In this case, a point taking WB within a one-field period limits the WB object area to a local part of small area which is not the whole of a screen. For instance, the area is set in common to an AF area or a photometric area, and if a white object exists within the area of small area, it will do. Therefore, the adjustment of WB corresponding to the color temperature becomes easy when a stroboscope photographing is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white balance adjusting device, and more particularly, to a white light which can automatically adjust the white balance of incident light including reflected light from a subject of projected light projected from a flash light emitting means. The present invention relates to a balance adjusting device.

[0002]

2. Description of the Related Art An image pickup device to which a conventional white balance adjusting device is applied will be described with reference to FIG. 5 showing a block configuration thereof. Continuous light reflected from a white subject 1 passes through an image pickup lens 2 and a diaphragm mechanism 3 is provided. An image is formed on the light receiving surface of the CCD solid-state image pickup device 4 via. The electric signal photoelectrically converted by the element 4 is subjected to signal processing by the camera process processing unit 5a and directed from the video signal output terminal 6 to an external device, for example N
It is output as a TSC composite video signal.

On the other hand, the camera process processing section 5a is
The R, G, B signals of the three primary colors are supplied to the CPU 7 which controls the operation sequence of the entire image pickup apparatus, and a gain control signal for adjusting the gain of the R, B signals is received from the CPU 7. There is. A one-touch WB (white balance) switch 8 is connected to the CPU 7.

In the conventional white balance adjusting device in the image pickup device thus configured, when the one-touch WB switch 8 is pressed, the CPU 7 takes in the R, G, B signals output from the camera process processing section 5a, In the CPU 7, the R, G and B signals are arithmetically processed, and R and B in the camera process processing unit 5a are set so that R / G = B / G = 1.
The gain of the signal amplification system is closed-loop controlled.

The above is the case where the light reflected from the white subject 1 is continuous light. However, when the reflected light is a single light emission, as in the case of shooting using a strobe as a flash light emitting means,
Conventionally, the white balance has been adjusted by the following means.

That is, since the color temperature of the flash light emitting means such as a strobe is known in advance, the R signal gain value and the B signal gain value corresponding to the color temperature of the flash light emitting means to be used are stored in advance in the ROM in the CPU 7. When the flash shooting mode is set, the above preset value is set in the CPU 7
The gains of the R signal amplifying system and the B signal amplifying system read out from are automatically set in the camera process processing unit 5a. In this way, the white balance during flash photography was adjusted without performing closed-loop control of one-touch operation.

[0007]

The R signal gain value and the B signal gain value corresponding to the color temperature of the strobe light to be used are stored in advance in the CPU 7 as preset values, and the camera is used at the time of stroboscopic photography. In the conventional white balance adjusting device in which the gain setting of each of the R and B signal amplification systems in the process processing unit 5a is forcibly replaced with the preset value, if the strobe is a type built in the image pickup device, the strobe is changed to the strobe. Since it can be specified, there is no problem even with the conventional means.

However, when a strobe is attached externally and the types thereof are not constant, or when a plurality of strobes are used in combination, the color temperature of the flash light emitting means cannot be specified, so that the conventional white balance adjusting device is applicable. Can not. Even in the case of the built-in flash, when using a slave strobe that emits light in synchronization with the flash emission from this built-in flash, or when it is mixed with other light such as external light, white balance can be adjusted by conventional means. I can't take it.

In other words, in the conventional white balance adjusting device at the time of shooting with a strobe, the R signal gain and the B signal gain are uniformly preset so as to match the color temperature of the assumed strobe regardless of the actual measurement. Therefore, it was not possible to deal with imaging by a light source deviating from the preset value.

Further, the reflected light from the white subject 1 is CCD
It is necessary to irradiate the entire area of No. 4 and it is difficult to find the white subject 1 that is irradiated over the entire light receiving surface of the CCD 4. Furthermore, the strobe light is likely to have uneven light distribution, which is bright in the center of the screen and dark in the periphery, so if the white balance is adjusted based on the entire area of this screen, stable white balance cannot be achieved. was there.

Therefore, an object of the present invention is to solve the above problems and more easily adjust the white balance corresponding to the color temperature of an actual light source even during flash photography.
Another object of the present invention is to provide a white balance adjusting device capable of performing stable white balance adjustment.

[0012]

SUMMARY OF THE INVENTION A white balance adjusting apparatus according to the present invention provides a flash light emitting means for projecting light onto an object and an incident light including reflected light of the projected projection light from the object. A video signal processing means for obtaining a corresponding video signal and a white balance target area, which is a target area for white balance adjustment, are switched from all areas of the screen to a partial area, and the white balance target area is switched. Adjusting means for performing a white balance adjusting operation based on the image signal.

[0013]

The present invention will be described below with reference to the illustrated embodiments. Prior to describing the embodiment of the present invention, the basic concept will be described first. Actually, stroboscopic light emission toward a white subject is actually performed once at a predetermined first timing within the V blanking period. Based on the image pickup signal obtained as a result, a white balance is attempted within the field period following the V blanking interval, which is the second timing after the first timing, and the type and combination of flash light emitting means are used. It aims to enable white balance adjustment corresponding to the color temperature of an actual light source regardless of the above. Hereinafter, a specific description will be given with reference to examples.

FIG. 1 is a block diagram of a main part of an image pickup apparatus to which the present invention can be applied. The white subject 1 to the one-touch WB switch 8 are the same as those shown in FIG. The same reference numerals are given and the description thereof is omitted, and only different members will be described below.

In FIG. 1, a CPU 7 for controlling white balance and strobe is connected with a strobe mode setting switch 17 for selecting a strobe light emission mode and a normal photographing mode, in addition to the one-touch WB switch 8 as an operation unit. Further, the strobe 16 is connected via the strobe light emission control unit 15.

Further, the CPU 7 has a VD corresponding to a field switching from a video sync signal generator 18 which generates a sync signal for timing the video signal.
Signal is being supplied. The generator 18 also supplies a synchronization signal to the camera process processor 5.

Between the processing unit 5 and the CPU 7, R
A / D for A / D converting each of the signal, B signal, and G signal
The digital data processed by the converters 12, 13, 14 and the CPU 7 are converted into R in the camera process processing unit 5.
The electronic volume 11 having a kind of D / A conversion function for converting into an analog value for gain and B gain setting is connected respectively.

Then, the flash mode setting switch 17
When a predetermined operation means represented by the one-touch WB switch 8 is operated in the mode in which the flash light emitting means is used, the flash light emitting means, that is, the strobe 16 at a predetermined first timing described later with reference to FIG. Issued by. Light projection timing control means for projecting such strobe light is formed by the CPU 7 or the like.

Further, a video signal corresponding to incident light including reflected light by the subject of the projection light projected at the above-mentioned first timing will be described later with reference to FIG. Video signal processing means obtained at the timing
The camera process processing unit 5 and the like are included.

Furthermore, the adjusting means for performing the white balance adjusting operation based on the video signal obtained at the second timing is A / D converters 12, 13, 14 and the electronic volume control 11.
Etc.

The operation of the apparatus of FIG. 1 configured as above will be described with reference to FIGS. FIG. 2 is a flowchart of the one-touch WB operation in the present embodiment, and waits until the one-touch WB switch 8 shown in FIG. 1 is operated and the signal from the switch 8 to the CPU 7 becomes active "L" (step S1).

When the one-touch WB switch 8 is pressed, V which is output corresponding to the switching of the field
It waits until the D signal becomes active "L" (step S2).

When the VD signal becomes active "L", the CPU 7 checks whether the strobe mode setting switch 17 shown in FIG. 1 is in the strobe light emission mode (step S3), and the strobe light emission is prohibited. If the normal shooting mode is set, the process proceeds to step S5. On the other hand, in the strobe light emission mode, the CPU 7 causes the strobe light 16 to flash through the strobe light emission control unit 15 shown in FIG. 1 (step S4), and then proceeds to step S5.

In step S5, the CPU 7 sets the R signal gain and the B signal gain to the initial value 0, and the initial setting value 0 is passed through the electronic volume 11 (see FIG. 1) (step S6) to perform the camera process process. It is supplied to the unit 5 and the R gain setting and B gain setting of the processing unit 5, that is, the adjustment voltage of the R signal amplification system and the B signal amplification system is set to zero. Therefore, both of the R signal output and the B signal output output from the processing unit 5 become 0, but since the adjustment voltage of the G signal amplification system is not variable, the reference value is output for the G signal. Here, the electronic volume data and the camera process processing unit 5
The relationship between the R signal gain and the B signal gain in is assumed as shown in Table 1 below.

[0025]

[Table 1]

Next, the timer means in the CPU 7 stands by for a predetermined time, which will be described later with reference to FIG. 3 (step S7). This predetermined time period is determined in relation to which part of the screen the white balance is to be adjusted, and will be described in detail in a second embodiment described later, but in the first embodiment, the V blanking period ends. It is said that the reading of the image information is started.

After waiting for a predetermined time, the CPU 7 A / D-converts the R, G, B signals from the camera process processing unit 5 by the A / D converters 12, 13, 14 and takes them into the CPU 7 (step S8). . In this case, R,
Each B signal is at the 0 level, while the G signal is at the reference value.

The CPU 7 calculates R / G and compares it with 1 (step S9). If it is equal to or larger than 1, it jumps to step S10 below and proceeds to step S11. In this case, the R and B signals are initialized to the 0 level in step S5, and the G signal is the reference value, so that R / G = 0 <1. Therefore, the process proceeds to step S10 to increase the R gain by +
The value is incremented by 1 and the process proceeds to step S11.

Similarly, with respect to the B signal, B / G is calculated and compared with 1 (step S11). If it is equal to 1 or larger than 1, step S12 is jumped to step S13. Also in this case, B / G = 0 <1, so the B gain is incremented by +1 (step S12).

The data of each R gain and B gain thus incremented is set in the electronic volume 11 (step S13), and the adjustment voltage of the R signal amplification system and the B signal amplification system in the camera process processing unit 5 is increased. Then, the process proceeds to step S14. The signal ratios R / G and B / G calculated in step S9 and step S11 are compared with 1 (step S14), and if at least one is smaller than 1, the process returns to step S8 and steps S8- S
14. Repeatedly executing 14, and when R / G ≧ 1 and B / G ≧ 1, it means that the white balance is achieved, and this flow is ended. FIG. 3 is a timing chart of the operation of each part of the present apparatus. At time t1, the strobe mode setting switch 17 is pressed,
When the signal level applied to U7 becomes active "H", this image pickup device enters the stroboscopic light emission mode.

When the one-touch WB switch 8 is pressed at time t2, the signal applied from the switch 8 to the CPU 7 becomes active "L". This corresponds to step S1 in the flowchart of FIG. 2, and will be simply referred to as (corresponding to S1) hereinafter.

One field period following the field including the time t2 starts from time t3 and continues until time t4. At the field start time t3, the signal corresponding to the field switching is substantially the same as the vertical synchronizing signal. The VD signal generated at the timing of becomes active "L" (corresponding to S2) and continues until time t5. In this case, since the strobe light emission mode is already set at the time t1 (corresponding to S3), the strobe light emission 31 is immediately performed (corresponding to S4).

The timing at which the strobe light emission 31 is performed is the predetermined first timing in the claims, which is started at time t3 in FIG. 3, which is V
If it is within the blanking period and before the photoelectric conversion of the CCD solid-state image sensor 4 is completed, the time t3 is reached.
It may be slightly delayed. In the device of this example, the video signal by the photoelectric conversion is obtained at a timing from time t6 slightly delayed from time t5 when the VD signal becomes non-active to time t4 when one field period ends.

White subject 1 by this strobe light emission 31
The reflected light from the image pickup lens 2 and the diaphragm mechanism 3 (see FIG. 1)
An image is formed on the light-receiving surface of the CCD 4 via the CCD, but since it is the reflected light from a uniformly white subject, the R, G, and B color components in the signal output accumulated in each pixel on the light-receiving surface are any. The same applies to pixels.

White subject 1 by the flash emission 31
The CCD output obtained by picking up the image is read from time t6 when the V blanking period ends, and the signal is processed by the camera process processing unit 5 to output the R signal output 32 and the G signal output 3
3, B signal output 34 is obtained. In this case, G signal output 3
3, the reference value is output as described above, but the R gain and the B gain are both initialized to 0 in the CPU 7, so that the R signal output 32 and the B signal output 34 are thick solid lines. Becomes 0 level (corresponding to S5 and S6).

A predetermined time (S
At time t7 when 7) has elapsed, the R signal output 32, G signal output 33, and B signal output 34 are A / D converted and input to the CPU 7 (S8 corresponding). These respective A / D inputs are calculated in the CPU 7 from time t8, that is, R / G and B / G are calculated and compared with 1 (S
9, corresponding to S11), and is incremented by 1 at time t9 (corresponding to S10 and S12) and data is set in the electronic volume 11 (corresponding to S13). With this data setting, the R signal output 32 and the B signal output 34 obtained by the camera process processing unit 5 have the levels of 32a and 34a, respectively.

At time t10, the A / D signal is input again and the above process is repeated, so that the R signal output 32 becomes 32b, 3b.
2c, ... Level rises in stages. Similarly, the B signal output 34 also rises to the levels of 34b, 34c, .... Then, the level 32m of the R signal output after the electronic volume data setting is performed at time t11 is set to the G signal output 33.
Since R / G ≧ 1, the calculation processing of the R signal system in the camera process processing unit 5 is ended.

Similarly, after setting the electronic volume data at time t12, the level 34n of the B signal output is compared with the G signal output 33, and B / G ≧ 1 is satisfied, so the processing of the B signal system is also completed (corresponding to S14). ). In the above description, the gain setting of the R signal amplification system is completed before that of the B signal amplification system, but it is needless to say that the opposite case is possible.

In order to measure the incident light including the reflected light from the subject at the time of stroboscopic light emission in the above-mentioned apparatus, the total exposure amount is measured at a constant time over the entire time period during the exposure, and this total exposure amount is measured. It may be a direct metering method that terminates the exposure operation when the exposure amount reaches a predetermined value, a pre-metering method that pre-meters before exposure and sets the emission time in advance, or any other existing metering exposure control method. Absent.

Further, the control as to whether or not strobe light emission is performed may be performed by manual operation of the strobe mode setting switch 17 or by an automatic strobe based on photometric information. That is, when adjusting the white balance according to this embodiment, it is not necessary to consider whether or not strobe light is emitted.

Further, steps S8 to S in FIG.
14, that is, the arithmetic processing operation from time t9 to time t13 in FIG.
Although the increment is made successively, it is also possible to carry out the arithmetic processing discretely and finely process from the point where R / G and B / G are close to 1. Alternatively, instead of starting with the initial value set to 0, it is possible to start from an intermediate value of the values of R gain and B gain, and the processing speed can be improved by these means.

FIG. 4 is a block diagram of the main part of an image pickup apparatus to which the white balance adjusting apparatus according to the embodiment of the present invention is applied. In the apparatus of FIG. 1 described above, the reflected light from the white subject 1 is entirely reflected by the CCD 4. Although it has been described that the area is illuminated, it may be difficult to search for a white object that is illuminated over the entire light receiving surface of the CCD. Therefore, in the present invention, CC
Instead of the entire area of D4, a part of the area is used to perform white balance with one touch.

This is, for example, AF in a normal camera.
A partial area for adjusting the white balance (hereinafter, referred to as WB) in the (autofocus) area or the photometry area.
It also means that it can be used as a target area).
The same members as those of the apparatus shown in FIG. 1 described above are designated by the same reference numerals, the description thereof will be omitted, and only different members will be described below.

In FIG. 4, the area designation signal from the area setting switch 21 for designating the WB target area is the CPU.
7, the CPU 7 sends the WB target area display information to the character mix circuit 22. Then,
The display information is mixed with the image information from the camera process processing unit 5 in the same circuit 22, and is displayed on the monitor by the EVF 23.

The method of setting the WB target area in this embodiment having the above-described structure will be described below. The WB target area is set to stand by for a predetermined time in step S7 of FIG. 2 in the above-described apparatus of FIG. The time is from time t6 to t7 in FIG. Therefore, the predetermined time from time t6 to time t7 is set to start reading the accumulated image information from each pixel of the CCD in time series in the above-described example, but the predetermined time is set in this embodiment. By lengthening the time, for example, the center of the CCD light receiving surface or an area preferred by the photographer is selected. In this case, it goes without saying that the time point when the white balance adjustment operation ends, that is, the times t11 and t12 in FIG. 3 must be within one field period.

According to the above-described embodiment, the white balance is set within one field period in the same manner as the apparatus of FIG. 1, but the WB target area is limited to a small area local area instead of the entire screen, for example, the AF area. Or it can be set in common with the photometric area, and it suffices if a white subject exists in the small area, so it is easier to adjust the white balance corresponding to the actual color temperature during flash photography. Further, as described above, by switching the WB target area to the central portion where the strobe light distribution is uniform, stable white balance adjustment can be performed.

In each of the above device examples, R, which is output from the camera process processing unit 5 for analog-processing the video signal,
A / D converters 12, 13 and 14 convert B and G signals into A / D signals.
Although it has been described that the data is D-converted and input to the CPU 7, CP
If the U7 having the above A / D conversion function is used, the R, B and G A / D converters 12, 13 and 14 become unnecessary. Further, if the camera process processing unit 5 is digitized, the electronic volume 11 is also unnecessary.

Although the flash light emitting means has been described as a strobe in each of the above-described embodiments, the present invention is not limited to strobe light, but can be widely applied to, for example, flash bulb light.

Further, in each of the above-mentioned embodiments, the white object is imaged and the white balance is taken, however, there are some commercially available video cameras and the like in which a white lens cap is attached to the front surface of the imaging lens. When the white lens cap is put on and an image is taken toward the light source for which white balance is desired, an effect equivalent to that when a white subject is taken is obtained. That is, since the white lens cap acts as a diffuser plate and averages the light from the light source,
This is because when viewed from the CCD, it is the same as when a subject whose entire surface is white is photographed, and the above-described embodiments are applicable to such a video camera.

[0050]

As described above, according to the present invention, it is possible to easily adjust the white balance corresponding to the color temperature of the actual light source even during flash photography, and to perform stable white balance adjustment. It can be carried out.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a main part of an image pickup apparatus to which the present invention can be applied.

FIG. 2 is a flowchart of a one-touch WB operation in the device shown in FIG.

FIG. 3 is a timing chart of the operation of each part in FIG.

FIG. 4 is a block configuration diagram of a main part of an image pickup apparatus to which a white balance adjusting apparatus according to an embodiment of the present invention is applied.

FIG. 5 is a block configuration diagram of a main part of an image pickup apparatus to which a conventional white balance adjustment apparatus is applied.

[Explanation of symbols]

 5, 5a Camera process processing unit 7 CPU 11 Electronic volume 12, 13, 14 A / D converter

Claims (3)

[Claims] 1. A flash light emitting means for projecting light on a subject, a video signal processing means for obtaining a video signal corresponding to incident light including reflected light of the projected projection light by the subject, and white balance adjustment. The white balance target area, which is the target area of the screen, is switched from the entire area of the screen to a partial area, and white balance adjustment operation is performed based on the video signal depending on the switched white balance target area. A white balance adjusting device comprising: 2. The white balance adjusting apparatus according to claim 1, wherein the partial area is a central portion of the screen. 3. The white balance adjusting apparatus according to claim 1, wherein the partial area is configured to be set in common with the photometric area.