JP3370358B2 - Video camera and photometric method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a video camera (including a still / movie video camera and a still video camera) that performs photometry of an object using a video signal obtained from a solid-state electronic image pickup device and determines exposure conditions. And a method of metering the same, and more particularly, to a video camera and a method of metering that are divided.

[0002]

BACKGROUND ART In a camera having an automatic exposure (so-called AE) function, photometry is necessary to determine an exposure condition. For example, when shooting under backlight conditions,
When the brightness of the subject in the shooting area greatly differs depending on the location, it is necessary to obtain a photometric value for each location of the subject (for each part) and perform appropriate exposure control accordingly. For this reason, so-called divided photometry is known in which the photographing area is divided into a plurality of small areas and a photometric value is obtained for each small area.

Divided photometry is performed by using a photometric element dedicated to divided photometry, which has a plurality of light receiving areas divided into a plurality of areas. However, when the photometric element dedicated to divided photometry is used, the divided photometric area is fixed. There is a problem that it cannot be changed if necessary.

Therefore, it is conceivable to use the video signal output from the solid-state electronic image pickup device provided in the video camera to perform the divided photometry. However, in this case as well, a detection circuit and an A / D converter are required for each of the plurality of divided photometric areas, which is an obstacle to downsizing, low power consumption, and cost reduction of the camera. If the photometric processing is performed for one divided photometric area for each one frame period or one field period, one set of detection circuit and A / D converter will suffice. There is a problem that the time becomes long.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to simplify the circuit configuration and to enable the photometry processing in a short time in the divided photometry using a video signal obtained from a solid-state electronic image pickup device.

According to the present invention, in a video camera having an image pickup optical system including a solid-state electronic image pickup device for converting an incident light image into a video signal and outputting the image signal, the solid-state electronic image pickup device is provided within a period in the horizontal scanning direction. Divided photometric area setting means for setting a plurality of divided photometric areas in the horizontal and vertical directions by respectively setting a plurality of horizontal photometric periods and a plurality of vertical photometric periods within the vertical scanning direction. A luminance signal extracting means for extracting a luminance signal component from a video signal output from the solid-state electronic image pickup device, and a luminance signal component extracted by the luminance signal extracting means,
One integrating circuit that integrates over a horizontal integration period designated by a given integration control signal and outputs a signal representing the integrated value, the horizontal direction of the divided photometric area being scanned for each of the divided photometric areas. integration control means for providing a photometric period the instructions for the integration control signal the one integrating circuit outputs as the integration period, vertical photometric period corresponding integrated values obtained from the single integration circuit for each of the divided photometric regions And the photometric value calculating means for calculating the photometric value for each of the divided photometric areas based on the value obtained by the addition, and the integrating circuit.
Integral processing and photometric value calculation by the photometric value calculation means
The above integration times are performed so that processing is performed within one field period.
Path, the integral control means and the photometric value calculation means are controlled.
It is equipped with a means to do.

According to the photometric method of the video camera of the present invention, a plurality of horizontal photometric periods are provided in the vertical scanning direction within a period in the horizontal scanning direction of the solid-state electronic image pickup device which converts an incident light image into a video signal and outputs the video signal. By setting a plurality of vertical photometric periods within the period, the divided photometric regions are divided into a plurality of horizontal and vertical directions, respectively.
For each of the divided photometric areas, a process of instructing the horizontal photometric period of the divided divided photometric area as an integration period by an integration control signal, extracting a luminance signal component from the video signal output from the solid-state electronic image sensor , integrates the luminance signal component using one of the integration circuit for the horizontal direction of the integration period designated by the integration control signal
And the integrated value obtained by the integration of the one integrating circuit are added over the vertical direction photometric period corresponding to each of the divided photometric regions, and the photometric value for each of the divided photometric regions is calculated based on the value obtained by the addition. Calculation process
This is done within one field period .

In the above invention, in the imaging area, it is defined by a plurality of horizontal direction photometric periods set in the horizontal scanning direction period and a plurality of vertical direction photometric periods set in the vertical scanning direction period. A plurality of divided photometric areas that do not overlap each other are set. Then, the integration of the luminance signal component extracted from the video signal is 1 with the horizontal photometry period as an integration period for each of the divided photometry regions.
It is performed by two integrating circuits. The integrated value obtained by the integration is added for each divided photometric area to obtain the photometric value for each divided photometric area. The photometric value may be calculated for a group of divided photometric areas formed by a combination of a plurality of predetermined divided areas.

According to the present invention, one photometric process is completed in one field period or one frame period of the video signal output from the solid-state electronic image pickup device, and a plurality of divided photometric values can be obtained simultaneously. The photometric processing time is shortened, and the photometric processing time up to the actual shooting can be shortened. Further, according to the present invention, since only one set of circuit means for photometry including the above-mentioned integrating means and A / D converter used when digital data is required, the circuit configuration is simplified and the camera is simplified. This contributes to downsizing, low power consumption, and low cost.

In a preferred embodiment of the invention,
By the A / D conversion means for converting the integrated signal output from the one integration circuit into digital data, and the A / D conversion means in the next horizontal scanning period in which the integration operation by the one integration circuit is performed. It further comprises A / D conversion control means for controlling the data conversion.

According to this embodiment, it is possible to secure a sufficient time for the A / D conversion processing by the A / D converter, so that the A / D conversion speed is not necessarily high and the A / D conversion is relatively inexpensive. A D converter (including a CPU with a built-in A / D conversion) can be used.

As described above, according to the present invention, photometric values can be obtained for a plurality of divided photometric areas or for a divided photometric area group consisting of a plurality of divided photometric areas. Therefore, exposure is performed using the obtained plurality of photometric values. Conditions can be set. Even if the brightness of the image within the field of view of the camera varies greatly from part to part, it is possible to determine an appropriate exposure condition according to the brightness and capture an appropriate image.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a digital still camera will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a digital circuit of an embodiment of the present invention.
It is a block diagram which shows the electric constitution of a still camera.

A clock signal generation circuit (hereinafter referred to as CG) 1 includes a clock signal CLK, a horizontal transfer pulse H for driving the horizontal transfer path of the CCD 4, a substrate extraction pulse SUB for sweeping unnecessary charges, and an A field vertical transfer. A pulse VA and a B field vertical transfer pulse VB are generated. Further, CG1 outputs a field index signal FI, an X timing signal XTM for strobe emission, and a horizontal synchronizing signal HD.

The clock signal CLK is given to a synchronizing signal generating circuit (hereinafter referred to as SSG) 2, and the SSG2 generates a horizontal synchronizing signal HD and a vertical synchronizing signal VD based on the clock signal CLK and gives them to CG1.

The horizontal transfer pulse H is given to a CCD (solid-state electronic image pickup device) 4, and the substrate extraction pulse SUB and the A field vertical transfer pulse VA are passed through a V driver 5 to
The B field vertical transfer pulse VB is applied to the CCD 4 via the V driver 6.

The field index signal FI, the X timing signal XTM and the horizontal synchronizing signal HD are the CPU
Given to 3. A shutter enable signal TS indicating that the exposure condition has been set from the CPU 3 to the CG 1.
An electronic shutter control signal TS1 that determines the timing for starting exposure is provided to EN and CCD4.

In the CCD 4, the substrate extraction pulses SUB, A
By the field vertical transfer pulse VA, the B field vertical transfer pulse VB, and the horizontal transfer pulse H, interlaced shooting is performed, and video signals of the A field and the B field (color sequential signals of GRGB) are alternately generated every one field period. Are sequentially read. The driving of the CCD 4 (imaging and reading of a video signal) is performed at least at the time of photographing and in the photometric processing prior thereto.

The video signals of the A field and the B field output from the CCD 4 are given to a color separation circuit 8 through a correlated double sampling circuit (CDS) 7 and three primary colors representing a subject image, G (green), R ( Red) and B
It is separated into (blue) color signals.

The color signals G, R, and B are subjected to color balance adjustment by a gain control circuit (hereinafter referred to as GCA) 9, and then gradation correction is performed by a gamma correction circuit 10 to perform clamp and reset. Input to the sampling circuit 11.

The clamp and resampling circuit 11 is
The three color signals R, G, B are clamped and re-converted into GRGB color sequential signals by resampling. This color sequential signal is input to the gain control and blanking circuit 12. The gain control and blanking circuit 12 amplifies the color sequential signal to an appropriate level for recording and adds the blanking signal to it. The output signal of the circuit 12 is subsequently converted into digital image data by the A / D converter 13.

As will be described later in detail, prior to photographing, photometric processing and exposure control (control of iris and shutter speed) based on the photometric value are performed. This photometric processing is GCA9.
Based on the output signal of Shooting is performed after such photometric processing, exposure control, and focusing control.
Then, the video signal obtained from the CCD 4 by photographing becomes digital image data through the circuits 10, 11, 12 and 13 described above, and is subjected to processing such as Y / C separation and data compression in an image data processing circuit (not shown). After that, it is recorded on a recording medium such as a memory card.

For photometric processing, a YL synthesizing circuit 14, a gate circuit 15, an integrating circuit 16 and an amplifying circuit 17 are provided. An example of a specific electrical configuration of these circuits is shown in FIG. The CPU 3 outputs window signals WIND1 to WIND5 for controlling the gate circuit 15 and a reset signal HLRST for resetting the integrating circuit 16. The timing of these signals WIND1 to WIND5 and HLRST will be described later. Further, in this embodiment, the CPU
3 has a built-in A / D converter 18.

The color signals R, G and B output from the gain control circuit 9 are added by the Y _L synthesizing circuit 14,
A relatively low frequency luminance signal Y _L (hereinafter simply referred to as luminance signal Y _L
Is generated). The luminance signal Y _L is the window signals WIND1 to WIN during the required horizontal scanning period.
Gate circuit for the period when any one of D5 is applied
Pass 15 The integrating circuit 16 is reset when the reset signal HLRST is given, and then integrates the luminance signal Y _L input from the gate circuit 15. The integrated signal of the integrating circuit 16 is amplified by the amplifying circuit 17, and immediately before the integrating circuit 16 is reset, it is converted into digital integrated data by the A / D converter 18 of the CPU 3 and taken into the CPU 3. Reference voltage divisions V1 and V2 of the integration circuit 16 and the amplification circuit 17
Gives an appropriate offset to this.

In this embodiment, the image pickup area of the CCD 4 is divided into 15 divided photometric areas, and the 15-divided photometry is performed to detect the photometric value for each divided photometric area. In addition, the A field image and B which form one frame
Since it is considered that the field image represents a field image at almost the same time point, in this embodiment, photometry is performed using the video signal of the A field. Of course, the photometry may be performed using the video signal of the B field, and the video signal of the B field can be used for other purposes such as other forms of divided photometry and focusing processing.

Further, in this embodiment, the integration by the integration circuit 16 and the A / D conversion operation and addition processing by the A / D converter 18 are alternately performed every horizontal scanning period.

FIG. 3 shows 15 divided photometric areas set in the photographing area 20 of the CCD 4.

The 15 divided photometric areas are divided into five scanning periods in the horizontal scanning direction of the photometric area 21 set over almost the entire photographing area 20, and three scanning periods in the vertical scanning direction.
It is set by dividing into two (3 rows and 5 columns of divided photometric areas).

That is, the horizontal direction of each divided photometric area is divided into 5 equal parts of 40 μs after 16 μs has elapsed from the fall of the horizontal synchronizing signal HD (at the start of the horizontal scanning period).
It is set for each μs period, and the vertical direction of each divided area is the 35th
It is set every 70 horizontal scanning periods obtained by equally dividing the interval from the th horizontal scanning line to the 244th horizontal scanning line into three equal parts.

Of the three-row, five-column divided photometric areas, the divided photometric areas of the first row are the first to fifth divided photometric areas from the left, and the divided photometric areas of the second row are the sixth to tenth divided photometric areas from the left. Third
The divided photometric areas of the row are the 11th to 15th divided photometric areas from the left.

FIG. 4 shows the integration time of the integrating circuit 16 and the window signals WIND1 to WIND5 for controlling the gate circuit 15 for each of the 15 divided photometric areas. The portion shown by the solid line in the horizontal scanning line is the integration time, and these integration times are defined by the corresponding window signal (any of WIND1 to WIND5). One window signal (one of WIND1 to WIND5) is generated per horizontal scanning line in the order of window signals WIND1, WIND2, ..., WIND5. The window signal is generated in the photometric area 21 (first
From the 35th horizontal scan line to the 243rd horizontal scan line). Further, as described above, in order to secure the A / D conversion time of the A / D converter 18, a window signal is generated for every other horizontal scanning line. Therefore, integration is performed seven times in each divided photometric area.

By the first window signal WIND1,
The horizontal integration times of the first, sixth and eleventh divided photometric areas belonging to the first column are defined. Similarly, the second window signal WIND2 and the third window signal WIND
3, second, seventh and twelfth divided photometric regions belonging to the second column, third, eighth and thirteenth divided photometric regions belonging to the third column, respectively by the fourth window signal WIND4 and the fifth window signal WIND5. Horizontal integration periods of the fourth, ninth, and fourteenth divided photometric regions belonging to the fourth column and the fifth, tenth, and fifteenth divided photometric regions belonging to the fifth column are defined.

The first to fifth window signals WIND
While any one of 1 to WIND5 is given, the gate circuit 15 allows the input luminance signal Y _L to pass through, and the luminance signal Y _L is input to the integrating circuit 16.

The integrating circuit 16 has already been reset in the preceding horizontal scanning period, and integrates the luminance signal Y _L which is input through the gate circuit 15. When the window signals WIND1 to WIND5 become L level and the input of the luminance signal Y _{L to} the integrating circuit 16 is stopped, the integrated output of the integrating circuit 16 is held as it is and the integrating circuit 16 is also held.
The integrated output of is converted into digital data by the A / D converter 18 incorporated in the CPU 3. After that, the integrating circuit 16 is reset by the horizontal line reset signal HLRST given from the CPU 3 to prepare for the next integrating operation.

A memory attached to the CPU 3 (for example, RA
M) is provided with the first to fifteenth divided photometric integrated data storage areas for the 15 divided photometric areas as shown in FIG. Each divided photometric integrated data storage area is cleared in synchronization with the 34th horizontal synchronizing signal HD or at the start of the A field. The integrated value converted into digital data by the A / D converter 18 is stored in the divided photometric integrated data storage area of the divided photometric area where this integrated value was obtained. Therefore, it is zero and is stored.

As described above, A / D by the A / D converter 18
The D conversion, the reset of the integration circuit 16, and the addition processing of the integrated data are performed in the horizontal scanning period subsequent to the horizontal scanning period in which the integration is performed.

As shown in FIG. 5, the integration of the luminance signal Y _L by the integrating circuit 16 on one horizontal scanning line in each divided photometric area and the integration in the next horizontal scanning period in which this integration is performed. Signal A / D conversion, integration circuit 16
And the addition of the integrated data to the memory are alternately repeated seven times for each divided photometric area, as described above.

In this way, the luminance signal Y _L is integrated every other horizontal scanning period, and A / D conversion and other processing are performed in the next horizontal scanning period after the integration. Even if a D converter is used, it can be sufficiently dealt with. Even if the integration is performed every other horizontal scanning line, it is possible to perform such integration on seven horizontal scanning lines in each divided photometric area. Therefore, obtain a sufficient amount of integrated data to obtain a photometric value. You can

FIG. 7 shows the overall operation of the divided photometric processing performed by the CPU 3.

The CPU 3 initializes the exposure condition when starting the photometric processing, and controls at least one of the iris and the electronic shutter so that the initial exposure condition is realized. As the initial exposure condition, a statistically most possible exposure condition, for example, an exposure charge Ev = 10 (aperture F4, shutter speed 1/60 seconds, or aperture F2, shutter speed 1/125 seconds) is preferable. Of course, it is also possible to perform preliminary photometry using a photometric element and to perform initial setting of exposure conditions based on this preliminary photometry result.

Three types of counters X, Y, and Z are used to perform integration, A / D conversion, and addition seven times for each of the 15 divided photometric areas. The counter X represents the column number of the divided photometric area, which is the window WIND1.
~ Matches the WIND5 number. The counter Y indicates the number of times of completion of a series of processes of integration, conversion to A / D, and addition of integration data performed in each divided photometric area. The counter Z represents the line number of the divided photometric area, and the first line is Z = 0,
The second row is set to Z = 5 and the third row is set to Z = 10. X + Z
Value matches the number of the divided photometric area (and the number of the divided photometric integrated data storage area of the memory). For example, for the eighth divided area, X = 3, Z = 5, and X + Z = 8. See FIGS. 3 and 5.

In the initial processing, these counters are
X = 1, Y = 0, and Z = 0 are set (step 51).

When the 34th horizontal synchronizing signal HD is detected (step 52), the horizontal line reset signal HLRS is detected.
T is output (step 53), which resets the integrating circuit 16.

When the next horizontal synchronizing signal HD is detected (the
When the next horizontal sync signal is detected for the first time after the 34th horizontal sync signal is detected, it is the 35th horizontal sync signal, and it is determined whether or not it has entered the photometric area) (step 54), the counter A window signal WINDX having a number corresponding to the value of X is given to the gate circuit 15 (step 55), and the integration circuit 16 integrates the luminance signal Y _L.

When the next horizontal synchronizing signal HD is detected (step 56), the integrated output from the integrating circuit 16 is A / D.
It is converted into digital data by the converter 18 (step 57), and then the horizontal line reset signal HLRST is generated.
Is output and the integrating circuit 16 is reset (step 5
8).

The digital integrated data A / D converted by the A / D converter 18 is stored in the X + Zth divided photometric integrated data storage area of the memory as the previous data (when Y = 0, there is no previous integrated data. Is added) and stored (step 59).

After this, the counter X is incremented (step 60) and it is judged whether or not X = 6 (step 61). If the value of the counter X is not 6, the process returns to step 54 to perform the photometric process for the next divided photometric area belonging to the same row.

For the divided photometric area designated by the incremented counter X value (Z = 0 at this time), the integration circuit 16 similarly integrates the luminance signal Y _L ,
A / D conversion of the integrated signal by the A / D converter 18, integration circuit
The process of resetting 16 and adding the integrated data to the corresponding divided photometric integrated data storage area is repeated while incrementing the counter X until X = 6 (steps 54 to 60).

The first photometric processing in each of the first to fifth divided photometric areas belonging to the first row is completed, and X = 6.
Then, the counter X is initialized again (X = 1) (step 62), and the counter Y is incremented by one (step 63). When the value of the counter Y reaches 7, it means that the photometry processing for 7 horizontal lines in the divided photometry area belonging to the first row is completed. Therefore, it is checked whether or not Y = 7 (step 64). If Y has not reached 7, the process returns to step 54, and the processes from step 54 to step 61 are repeated.

When the photometric processing in the first to fifth divided photometric processing belonging to the first row is completed (Y = 7) (step 6)
4) The counter Y is initialized (step 65) and 5 is added to the counter Z (Z = 5) in order to perform the photometric processing for the sixth to tenth divided photometric areas belonging to the second row.
(Step 66). After this, go back to step 54 and step
By repeating steps 54 to 64, the photometric processing is performed for the sixth to tenth divided photometric areas belonging to the second row.

When the photometric processing for the divided photometric areas of the second row is completed (YES in step 64), the counter Y is initialized again and 5 is added to the counter Z (Z = 10).
Then, similarly, the photometric processing is performed on the 11th to 15th divided photometric areas belonging to the third row. Finally, if Z = 15, the photometric processing for all the divided photometric areas is completed.

As described above, when the added value of the integrated data in each of the 15 divided photometric regions is obtained,
A photometric value for each divided photometric area is calculated as necessary based on the added value. The added value itself may be used as the photometric value, or the photometric value can be obtained by performing an appropriate calculation (for example, multiplying a predetermined coefficient) on the added value. It is not always necessary to obtain the photometric value for each of the 15 divided photometric areas. Only the photometric value required for exposure control needs to be obtained. As will be described later, an average photometric value for a plurality of divided photometric areas may be calculated.

The exposure conditions are set based on the divided photometric values of the first to fifth divided photometric areas (these are EV1 to EV15) obtained as described above, for example, as follows. .

FIG. 8 shows a CPU for setting exposure conditions.
3 is a flowchart showing a processing procedure performed by No. 3.

The CPU 3 obtains an average photometric value (hereinafter referred to as upper average photometric value) EV _AVU of the divided photometric values EV1 to EV5 from the first divided photometric region to the fifth divided photometric region (hereinafter referred to as upper photometric region). (Step 71).

Next, the divided photometric value E from the sixth divided photometric region to the fifteenth divided photometric region (hereinafter referred to as the lower photometric region)
The average photometric value of V6 to EV15 (hereinafter referred to as the lower average photometric value) EV _AVD is obtained (step 72).

Next, the average photometry value of the divided photometry values EV1 to EV15 from the first division photometry area to the fifteenth division photometry area (hereinafter referred to as the average photometry area), that is, the photometry area 21.
The average photometric value (hereinafter, referred to as average photometric value) EV _AV of the whole (see FIG. 3) is obtained (step 73).

Next, the average photometric value (hereinafter referred to as spot photometric value) EV _SP of the divided photometric values EV7 to EV9 from the seventh divided photometric region to the ninth divided photometric region (hereinafter referred to as spot photometric region) is obtained ( Step 74).

It is judged whether or not the average photometric value EV _AV is 9.0 EV or less (step 75), and EV _AV ≤9.0
When it is determined to be EV, that is, when it is determined that the brightness of the subject in the average photometry area is low,
Since it is necessary to brighten the subject, preparation for strobe emission for shooting with low-luminance strobe emission and exposure conditions for strobe emission are set (step 76).

If it is determined in step 75 that EV _AV ≤9.0 EV is not satisfied, that is, if it is determined that the brightness of the subject in the average photometric area is high,
Further, it is determined whether the lower average photometric value EV _AVD is 9.0 EV or less (step 77). EV _AVD ≤ 9.0 EV
If it is determined that, as in the case of the determination of the average photometric value EV _AV , the process proceeds to step 76 and the preparation for strobe emission and the exposure condition at the time of strobe emission are set in order to perform photographing by low-luminance strobe emission.

As described above, the lower average photometric value EV _AVD is further determined by determining that a high-luminance object such as sky exists in the upper photometric area and a main object such as a person exists in the lower photometric area. Considering such a case, even if the luminance of the main subject is small, the average photometry value EV _AV becomes large due to the high-luminance subject. Therefore, if only the average photometric value EV _AV is determined, it is determined that the strobe emission is not necessary, and the main subject is photographed in the dark.

In step 77, EV _AVD ≤9.0 EV
If not, that is, if the brightness of the subject in the lower photometry area is high and therefore the entire subject is bright, then the average brightness measurement is performed to determine the brightness difference between the main subject and the background. Taking the difference ΔEV ₁ (= EV _AV −EV _SP ) between the value EV _AV and the spot metering value EV _SP ,
If the difference ΔEV ₁ between the photometric values is smaller than 0.5 EV,
Greater than or equal to EV and less than 1.0 EV, or 1.0 E
It is determined whether or not it is V or more (step 78).

At step 78, ΔEV ₁ <0.5 EV
If it is determined that the brightness difference between the main subject and the background is small, the brightness difference between the subject in the upper photometric region and the subject in the lower photometric region is determined,
Furthermore, the upper average photometric value EV _{AV U} and the lower average photometric value EV
_AVD difference ΔEV ₂ (= EV _AVU −EV _AVD ) is taken, and this photometric value difference ΔEV ₂ is smaller than 1.0 EV or 1.0 EV.
It is determined whether it is V or more and 3.0 EV or less, or greater than 3.0 EV (step 79).

At step 79, ΔEV ₂ <1.0 EV
If it is determined that the brightness difference between the subject in the upper photometry area and the subject in the lower photometry area is small, and there is no portion with a large brightness difference over the entire subject, the average photometry value EV _The exposure condition is set based on the _AV (step 80).

In step 79, 3.0 EV ≧ ΔEV ₂
When it is determined that ≧ 1.0 EV, that is, when the subject in the upper photometric area is brighter than the subject in the lower photometric area, the exposure condition is set based on the lower average photometric value EV _AVD. (Step 81). This is because if the exposure condition is set based on the average photometric value EV _AV , the subject in the lower photometric area including the main subject is photographed darkly, and the main subject that the photographer wants to photograph most is properly exposed. Is considered the best.

At step 79, ΔEV ₂ > 3.0 EV
If it is determined that the subject in the upper metering area is brighter than the subject in the lower metering area and the difference in luminance is very large, the upper average metering value EV _AVU and the lower average _meter Average value of photometric value EV _AVD (EV
_The exposure condition is set based on _AVU + EV _AVD ) / 2 (step 82). That is, in this case, exposure correction (backlight correction) is performed so that the subject in the upper photometric area becomes dark and the subject in the lower photometric area becomes bright.

In step 78, 0.5 EV ≦ ΔEV ₁
If it is determined to be <1.0 EV, that is, if the main subject is darker than the background, the exposure condition is set based on the spot photometric value EV _SP (step 8).
3). In this case, it is considered that it is best to properly expose the main subject that the photographer wants to photograph most, even if the background is sacrificed to some extent.

At step 78, ΔEV ₁ ≧ 1.0 EV
If it is determined that the main subject is darker than the background and the brightness difference is extremely large, it is necessary to light the strobe to brighten the main subject. For flash firing and setting the exposure conditions for flash firing (step
84).

In the above embodiment, the divided photometric areas of 3 rows and 5 columns are set, but it goes without saying that the divided photometric areas can be arbitrarily set according to the purpose of photographing. For example, the divided photometric area for obtaining the spot photometric value may be set wider than the other divided photometric areas. It is also possible to use the B field video signal to obtain the average photometric value. The exposure control may use divided photometric areas, or an average photometric value of a plurality of divided photometric areas as shown in FIG.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital still camera according to an embodiment of the present invention.
It is a block diagram which shows the electric constitution of a video camera.

2 is a circuit diagram showing a more specific electrical configuration of a circuit portion required for photometry in the digital still video camera of FIG.

FIG. 3 is a diagram showing divided photometric areas set within a shooting area.

FIG. 4 is a diagram showing a scanning method in each divided photometric area.

FIG. 5 is a time chart of divided photometry.

FIG. 6 is a diagram showing a divided photometric integration data storage area of a memory.

FIG. 7 is a flowchart showing a procedure of a divided photometry process by a CPU.

FIG. 8 is a flowchart showing a procedure of setting exposure conditions based on divided photometric values by a CPU.

[Explanation of symbols]

3 CPU 4 CCD 14 YL synthesis circuit 15 gate circuit 16 Integrator circuit 20 Shooting area 21 Metering area

Continued front page    (72) Inventor Takashi Soga               Fuji, 3-1-1, Izumi, Asaka-shi, Saitama Prefecture               Inside Photo Film Co., Ltd. (72) Inventor Shigekazu Fukada               Fuji, 3-1-1, Izumi, Asaka-shi, Saitama Prefecture               Inside Photo Film Co., Ltd.                (56) Reference JP-A-4-84574 (JP, A)                 JP-A-4-101125 (JP, A)                 Japanese Patent Laid-Open No. 4-175076 (JP, A)                 Japanese Patent Laid-Open No. 4-195026 (JP, A)                 JP-A-3-99587 (JP, A)                 JP-A-3-203473 (JP, A)

Claims (12)

(57) [Claims] 1. A video camera provided with an image pickup optical system including a solid-state electronic image pickup device for converting an incident optical image into a video signal and outputting the image signal, wherein a plurality of video cameras are provided within a period in the horizontal scanning direction of the solid-state electronic image pickup device. Divided photometric area setting means for setting a plurality of divided photometric areas in the horizontal and vertical directions by setting a plurality of horizontal photometric periods in the vertical scanning direction, respectively. Luminance signal extraction means for extracting a luminance signal component from a video signal output from the solid-state electronic image pickup device, and a horizontal integration period designated by an integration control signal given to the luminance signal component extracted by the luminance signal extraction means. One integrating circuit that integrates over and outputs a signal representing the integrated value, the divided photometric area being scanned for each of the above divided photometric areas Integration control means for applying to said horizontal photometric period instructs the integration control signal the one integrating circuit outputs as the integration period, vertical to the corresponding integral value obtained from the one integrating circuit for each of the divided photometric regions added over direction photometric period, photometric value calculating means for calculating a photometric value for each of the divided photometric regions, based on the value obtained by the addition, as well as the
Integral processing in the integrating circuit and the photometric value calculation means
Perform the photometric value calculation process in 1 field period
The integration circuit, the integration control means, and the photometric value
A video camera equipped with means for controlling the calculation means . 2. The video according to claim 1, wherein the integration control means outputs an integration control signal indicating a horizontal photometry period of one divided photometry area in one horizontal scan.
camera. 3. An A / D converting means for converting an integrated signal output from the one integrating circuit into digital data, and a horizontal scanning next to a horizontal scanning period in which the integrating operation is performed by the one integrating circuit. The video camera according to claim 1, further comprising: an A / D conversion control unit that controls the data conversion by the A / D conversion unit during a period. 4. The video camera according to claim 1, wherein the photometric value calculation means calculates a photometric value for a group of divided photometric areas formed by a combination of a plurality of predetermined divided photometric areas. . 5. The video camera according to claim 1, further comprising exposure control means for determining an exposure condition based on photometric values of a plurality of divided photometric areas calculated by the photometric value calculating means. 6. The photometric value calculating means calculates a photometric value for each of a plurality of divided photometric area groups each of which is composed of a combination of a plurality of predetermined divided photometric areas. The video camera according to claim 1, further comprising exposure control means for determining an exposure condition based on photometric values of a plurality of divided photometric area groups calculated by the calculation means. 7. A plurality of horizontal direction photometric periods within a horizontal scanning direction period of a solid-state electronic image pickup device which converts an incident light image into a video signal and outputs the video signal, and a plurality of vertical direction photometric periods within a vertical scanning direction period. By setting the respective periods, a plurality of divided photometric regions are set in the horizontal and vertical directions respectively, and the horizontal direction photometric period of the divided photometric regions being scanned is integrated for each divided photometric region. Process as instructed as an integration period, a luminance signal component is extracted from the video signal output from the solid-state electronic image pickup device, and this luminance signal component is integrated over the horizontal integration period instructed by the integration control signal. Integrate using a circuit
And the integrated value obtained by the integration of the one integrating circuit are added over the vertical direction photometric period corresponding to each of the divided photometric regions, and the photometric value for each of the divided photometric regions is calculated based on the value obtained by the addition. Calculation process
A photometric method for a video camera that is performed within one field period . 8. The photometric method for a video camera according to claim 7, wherein the integration control signal indicates a horizontal photometric period of one divided photometric area in one horizontal scan. 9. The photometric method for a video camera according to claim 7, wherein the conversion of the integrated signal representing the integrated value into digital data is performed in the horizontal scanning period subsequent to the horizontal scanning period in which the integration is performed. . 10. The video camera according to claim 7, wherein the calculation of the photometric value is to calculate the photometric value for a group of divided photometric areas formed by a combination of a plurality of predetermined divided photometric areas. Photometric method. 11. The photometric method for a video camera according to claim 7, wherein the exposure condition is determined on the basis of the photometric values of the plurality of divided photometric areas calculated by the calculation of the photometric value. 12. The photometric value is calculated for each of a plurality of divided photometric area groups each consisting of a combination of a plurality of predetermined divided photometric areas. The exposure condition is determined based on photometric values of a plurality of divided photometric area groups calculated by the calculation of
The photometric method of the video camera described in.