JPH0983860A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the exposure control performance under the condition of counterlight or the like by specifying a picture element block in which an object is in existence and controlling a shutter based on a photometric value. SOLUTION: A camera signal processing circuit 5 processes an image pickup signal received via a lens 1, a CCD image pickup element 3, and an amplifier circuit 4 or the like to generate a luminance signal and a color difference signal and provides an output of a video signal such as an NTSC signal to an output terminal 11. An object extract circuit 6 extract a object photometric area of a square surrounding the object on a prescribed extract condition. A sampling detection circuit 9 divides the object photometric area into blocks each consisting of, e.g. 32-picture elements × 16-line and checks a color difference coordinate as to a middle picture element. To a color difference coordinate plane, e.g. 'skin color', 'hair color (black)', 'color of clothing (green)' areas are set in advance and when the middle picture element is in matching with any of them, it is judged that the object is in existence in the block. An arithmetic circuit 10 controls the exposure based on the photometric value as to the block where the object is in existence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement in the performance of the exposure control function of an image pickup apparatus, and in particular, it prevents the exposure control performance from deteriorating even in the case of backlight or over-forward light so that the subject is always kept at an appropriate brightness. The present invention relates to an image pickup device that enables exposure control.

[0002]

2. Description of the Related Art Generally, an image pickup apparatus has an exposure control function for controlling the amount of incident light so that the level of an output video signal becomes a constant value. In the exposure control, the average signal level in the imaging screen is detected from the video signal,
A method of feedback controlling the aperture value and the shutter speed is generally adopted so that the detected value and the preset reference value match. At this time, change the video signal level to
A commonly used method is to extract a photometric value by extracting from a specific photometric area having a fixed size, such as a rectangular area including the center point of the imaging screen.

However, when the position where the subject is present deviates from the specific photometric area, the photometric value for the subject portion may not be properly detected by the above-described method. It becomes a problem under the conditions of backlight and over-forward light.

Therefore, in order to always make the subject portion of interest have an appropriate brightness, there is provided a device for determining the position and size of the subject in the photographic screen and changing the position and size of the photometric area accordingly. Was proposed. In addition, the photometric area of the subject at this time is generally an area having a rectangular shape. Examples of such conventional technology include, for example,
The technology is disclosed in Japanese Patent Application Laid-Open No. 1-120181.

[0005]

However, since the conventional photometric area of the subject is rectangular, the subject may be in the photometric area depending on the shape of the subject, especially under conditions such as backlight and over-lighting. Since it is affected by the photometric value of the area other than the accurate photometric value of the subject itself,
There is a problem of exposure control performance deterioration in that the photometric value of the subject portion cannot be detected properly and the exposure control cannot be performed accurately.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above problems and provide an image pickup apparatus having an exposure control function for keeping an object at an appropriate brightness.

[0007]

In order to solve the above problems and achieve the object of the present invention, there are the following means.

That is, an image sensor for photoelectrically converting incident light to output an image signal, and a signal processing means for generating a video signal including a color difference signal and a luminance signal from the image signal output by the image sensor are generated. A subject extraction unit that outputs information on a subject photometric region that is a region including a subject and has a predetermined shape based on the video signal, and a region other than the subject region by referring to the video signal and the subject photometric region. With reference to the video signal and the subject photometric area, the subject photometric area is divided into blocks of a predetermined size, and the luminance signal for the block in which the subject is present is added. Sampling detecting means for outputting the added photometric value, the background photometric value output by the variable area signal detecting means, and the sample A calculation unit that calculates an exposure control amount based on the photometric value output by the detection unit; and an exposure control unit that controls the exposure amount of the image sensor based on the exposure control amount calculated by the calculation unit. It is an imaging device that has.

Further, as another aspect of the present invention, there are also means shown below.

That is, the calculation means is further provided with a background photometric value output from the variable area signal detection means, and
Based on the photometric value output by the sampling detection means, it is configured to have a function of calculating the contrast between the background and the subject, and whether it is in the backlight state or the over-lighting state according to the contrast calculated by the calculation means. The image pickup apparatus is provided with a state determination unit for determining.

[0011]

The image pickup device photoelectrically converts incident light to output an image pickup signal, and the signal processing means generates a video signal including a color difference signal and a luminance signal from the image pickup signal output from the image pickup device.

Next, the subject extracting means outputs information on a subject photometric region which is a region including the subject and having a predetermined shape (most commonly, a rectangular shape) based on the generated video signal.

Further, the variable area signal detecting means detects the photometric value of the background, which is an area other than the object area, by referring to the video signal and the object photometric area, and the sampling detecting means, the sampling detecting means. The subject photometric area is divided into blocks of a predetermined size with reference to the subject photometric area, the luminance signals for the blocks in which the subject is present are added, and the added photometric value is output.

The calculation means calculates the exposure control amount based on the photometric value of the background output by the variable area signal detection means and the photometric value output by the sampling detection means, and the exposure control means The exposure amount of the image pickup device is controlled based on the exposure control amount calculated by the calculation means.

Further, the calculation means further includes: a photometric value of the background output by the variable area signal detection means; and a photometric value output by the sampling detection means.
In the case of the configuration having the function of calculating the contrast between the background and the subject, the state determination means determines whether the backlight state or the over-forwarding state is in accordance with the contrast calculated by the calculation means.

According to the present invention, it is possible to detect the photometric value of each of the blocks constituting the object photometric area approximated by a rectangle, for example, to improve the accuracy of exposure control. The performance of exposure control is prevented from deteriorating at the time of backlighting and over-forwarding, and the exposure control which always makes the subject an appropriate brightness is possible.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an image pickup apparatus according to the first embodiment of the present invention.

Reference numeral 1 is a lens, 3 is an image pickup device, and the image pickup device 3 is, for example, a CCD (Charge Coupled Device).
It can be realized by an optical element such as.

The lens 1 receives the incident optical signal from the CCD (Cha
An image is formed on the image pickup device 3 such as a large coupled device).

The image pickup device 3 converts the optical signal formed by the lens 1 into an electric signal and outputs the image pickup signal. The operation timing of the image pickup device 3 and the time for one photoelectric conversion, that is, the shutter speed are controlled by the image pickup device drive circuit 2.

Reference numeral 4 denotes an amplifier circuit, which is a circuit for amplifying an analog image pickup signal to a signal level required in the subsequent processing. Further, it is preferable to have a configuration in which other processing of amplification of the image pickup signal, for example, noise reduction processing such as correlated double sampling is performed.

A camera signal processing circuit 5 converts an analog image pickup signal into a digital signal, and then performs known signal processing such as clamping, gamma correction, and white balance correction to obtain a luminance signal and a color difference signal. To generate. In addition, it also has a function of converting these signals into a standardized format of a video signal such as NTSC and outputting from the output terminal 11.

The subject extraction circuit 6 regards an area that satisfies a certain extraction condition as a subject on the basis of the video signal output from the camera signal processing circuit 5 and extracts it, and also information such as the size and position of the area. Is output to the control circuit 7. As described above, regarding the method of extracting the subject, Japanese Patent Laid-Open No. 4-2
Publicly known techniques described in publications such as No. 05070 and documents such as "1993 National Conference of Television Society Proceedings, pp. 91 to 92" can be used.

The control circuit 7 outputs the extraction range of the subject to the subject extraction circuit 6 so that the subject photometric area that matches the shape of the subject can be extracted later. That is, the size of the subject (for example, the vertical and horizontal coordinates of a rectangle surrounding the subject) and position information are output to the variable region signal detection circuit 8 and the sampling detection circuit 9. A rectangular area including the subject is referred to as a subject photometric area.

It should be noted that the color difference signal and the luminance signal of the subject are also output to the sampling detection circuit 9.

A variable area signal detection circuit 8 detects the photometric value of the background (a portion other than the subject) based on the video signal converted into a digital signal by the camera signal processing circuit 5, and calculates the detected photometric value. Output to the circuit 10.

Now, here, the subject photometric area (rectangle),
The concept of the background photometric area will be described.

The variable area signal detection circuit 8 first sets the photometric area based on the size and position information of the subject output by the control circuit 7.

As shown in FIG. 2, an area having a rectangular shape surrounding the object is defined as an area of the object, and the area having the rectangular shape is referred to as an "object photometric area". On the screen,
An area other than the subject photometric area is set as a background area, which will be referred to as a "background photometric area" (a shaded area in FIG. 2).
Then, after setting the region, the background photometric value is detected from the background photometric region.

If necessary, the photometric value of the subject photometric area may be detected. In addition, the variable region signal detection circuit 8
Is configured to also obtain the area of the background photometric area.

On the other hand, the sampling detection circuit 9 divides the subject photometric area into a plurality of blocks, judges the presence or absence of the subject in each block based on the color difference and luminance information, and collects the blocks in which the subject exists. Then, a subject photometric region that matches the shape of the subject is extracted, and the photometric value in the extracted region is detected. Then, the detected photometric value of the subject is output to the arithmetic circuit 10.

Here, the shape of the subject is determined in the rectangular subject photometric area, the photometric value for the determined subject is detected, that is, the subject photometric area that matches the shape is extracted, and the photometric value in the extracted area is determined. The principle of detection will be described.

First, as shown in FIG. 3A, a rectangular subject photometric area is defined as a vertical "15", a horizontal "12", that is, "1".
It shall be divided into 2 × 15 ”blocks. That is, as shown in the figure, the subject photometric area is divided into meshes. In FIG. 3A, the shaded area is the background photometric area. Further, “12 × 15” is an example of division.

At this time, if the size of one block is as small as possible, the shape of the object can be determined faithfully, but one block is "32 pixels x
The size should be about 16 lines. The operation of the sampling detection circuit 9 will be described in detail later. In FIG. 3B, an example of the result of extracting a subject photometric area that matches the shape is shown by black hatching. As can be seen from the state shown in the figure, in FIG. 3B, the subject conventionally treated as a rectangular subject photometric region is set in consideration of the shape of the subject itself. This enables highly accurate exposure control.

The arithmetic circuit 10 calculates the weighted average photometric value in consideration of the "weighting coefficient" for the subject photometric area matched to the shape, and obtains the exposure control amount for reproducing the subject to an appropriate brightness. Output.

The control circuit 7 obtains the weighting factor from the position information of the subject and outputs it. A method for obtaining such a weighting factor is a known technique, and thus a detailed description will not be given here. The arithmetic circuit 10 will be described later in detail.

In this embodiment, the exposure control is realized by the image pickup element drive circuit 2 by making the shutter speed of the image pickup element 3 variable. That is, the image pickup device drive circuit 2 is configured to be able to perform exposure control by driving the image pickup device 3 so as to obtain a desired shutter speed based on the output signal of the arithmetic circuit 10. .

Now, the operation of the sampling detection circuit 9 will be described.

FIG. 4 is a block diagram of the sampling detection circuit 9 in FIG.

The input terminals 44 and 45 are terminals for receiving signals sent from the control circuit 7 and the camera signal processing circuit 5, respectively.

Reference numeral 41 denotes a YC data sampling circuit, which is a block (51) forming a rectangular object photometric area.
2 pixels: 32 pixels × 16 lines) is a means for detecting color difference and luminance information of one pixel at the center.

The judgment circuit 42 detects the color difference and brightness information detected by the YC data sampling circuit 41 and the extraction condition (color and brightness) of the subject, which is input through the input terminal 44 and is predetermined. Luminance extraction range), and outputs the position information of the block in which the pixel exists only when the extraction condition is satisfied, that is, when the detected pixel constitutes the subject.

The integrator circuit 43 refers to the video signal input through the input terminal 45, detects the photometric value of the block corresponding to the position information output by the determination circuit 42, and sequentially adds the detected photometric values. Perform the processing. The added photometric value is used as the photometric value of the subject and is output to the arithmetic circuit 10 via the output terminal 45.

The obtained photometric value of the subject is shown in FIG.
The photometric value for the subject photometric area is as shown in. This is a photometric value for the extracted subject when it is assumed that only the subject portion is extracted from the rectangular subject photometric area.

Next, a method of determining whether or not a subject is present in each block will be described.

The above-mentioned extraction conditions are the color difference planes having gradations of 0 to 255 ("RY" axis, "BY" axis).
Of the subject's color range and the subject's luminance range on the luminance axis having gradations of 0 to 255.

FIG. 5 shows an extraction range on an object existing in a rectangular object photometric area and on a color difference plane (two-dimensionally representing a hue. The vertical direction represents "red" and the horizontal direction represents "blue"). An example of the correspondence with Since the concept of the brightness range is the same as that of the color difference plane, the description of the brightness direction will be omitted. In the figure, the coordinates existing in the front direction from the other side become the luminance axis.

The color ranges of "skin color", "hair color (black)" and "clothes (green)" of the subject shown in FIG. 5A are shown in FIG.
It corresponds to a square area on the color difference plane shown in (b).

That is, the areas a, b shown in FIG.
Regions c correspond to the “skin color”, “hair color (black)”, and “clothes (green)” of the subject, respectively. Usually, the color exhibited by an object has a certain range in this way.

Therefore, the determination circuit 42 determines that the subject exists in the block in which the pixel is present when the pixel color is present in any of the regions showing black, flesh color, and green. The information on the area as shown in FIG. 5B may be set in the determination circuit 42.
It should be noted that the brightness information may be used to determine whether or not the block includes the subject.

Next, the arithmetic circuit 10 will be described.

FIG. 6 is a block diagram of the arithmetic circuit 10.

The input terminals 64, 65 and 66 respectively have a control circuit 7, a sampling detection circuit 9 and a variable area detection circuit 8 respectively.
Is a terminal for inputting a signal from the output terminal 67
Is a terminal for outputting a signal to the image sensor drive circuit 2.

First, the subject average photometric value calculation circuit 61
A process of dividing the photometric value of the subject output by the sampling detection circuit 9 by the area of the subject to calculate the average photometric value of the subject per unit area (subject average photometric value), and outputting it to the exposure control amount calculation circuit 63 To do.

Next, the background average photometric value calculation circuit 62 divides the photometric value of the background photometric area output from the variable area signal detection circuit 8, that is, the photometric value for the background by the area of the background, A process of calculating an average photometric value of the background (background average photometric value) and outputting it to the exposure control amount calculation circuit 63 is performed. Then, the exposure control amount calculation circuit 63 obtains the weighted average photometric value of the entire screen by using the average photometric value of the subject, the average photometric value of the background, and the weighting coefficient given to the subject and the background through the input terminal 64. .

That is, assuming that the weighting factors for the object and the background are wo and wb, respectively, and the average subject photometric value and the background average photometric value are Soav and Sbav, respectively, the weighted average photometric value of the entire screen is "wo・ Soav + wb ・ S
“Bav”.

Further, the exposure control amount calculation circuit 63 calculates the control amount of the shutter speed that keeps the weighted average photometric value of the entire screen constant. That is, "wo Soav +
wb · Sbav = reference value + f (Sbav / Soav):
The control amount of the shutter speed is calculated so that the expression "f is a function defined by Sbav / Soav" is satisfied.

Then, it outputs to the arithmetic circuit 10 through the output terminal 67. The image sensor drive circuit 2 includes an arithmetic circuit 10
The exposure control is performed by controlling the shutter speed based on the control amount sent from.

The second embodiment of the present invention will be described below.

In the first embodiment, in order to obtain the photometric value of the subject from the rectangular subject photometric region, the determination is performed using the subject color difference and the luminance information. In the present embodiment, the rectangular subject photometric region is used. The feature is that the photometric value of the subject is obtained using the peak value and so on.

Further, in the first embodiment, only the shutter speed is controlled for the exposure control, but in the present embodiment, not only the shutter speed but also the diaphragm and the amplification degree in the signal processing are controlled at the same time.

FIG. 7 is a block diagram of the image pickup apparatus according to the present embodiment. The components common to the block diagram shown in FIG.
The same reference numerals are given and the description of the functions and operations is omitted.

Reference numeral 14 is a diaphragm for adjusting the amount of incident light,
Reference numeral 15 is an aperture drive circuit for controlling the aperture value and setting the aperture value to a desired value. Reference numeral 16 denotes a variable amplifier circuit, which has a function of increasing the amplification degree and varying the amplification degree so that the reproduction signal level becomes constant when the illuminance becomes low.

The sampling detection circuit 17 compares the photometric value for the block with the peak value or the like of the photometric value in a rectangular subject photometric area composed of a plurality of blocks (referred to as "boundary value"), The shape of the object is grasped, the photometric value corresponding to the shape of the subject is detected, and the obtained photometric value of the subject is output to the arithmetic circuit 18.

The operation of the sampling detection circuit 17 is the same as that of the first embodiment in that the photometric value of the subject is detected, but the method for determining whether or not the subject is present in each block to be detected is different. Therefore, this point will be described later.

FIG. 8 shows a block diagram of the arithmetic circuit 18. In the arithmetic circuit 18 of the second embodiment, a contrast calculating circuit 81 is newly added to the arithmetic circuit 10 of the first embodiment,
The output terminal 84 is provided.

The exposure control amount calculation circuit 63 obtains the weighted average value of the entire screen by using the weighting factors of the subject and the background, which are given through the input terminal 64, for the subject averaged photometric value and the background averaged photometric value. This method of obtaining is the same as that of the first embodiment.

Then, the shutter speed, the signal amplification degree, and the aperture control amount are calculated so that the weighted average value of the entire screen is kept constant.

The output terminal 67 outputs the control amount for the shutter speed, the output terminal 82 outputs the control amount for the amplification degree of the signal, and the output terminal 83 outputs the control amount for the diaphragm.

The signals output from the output terminals 67, 82 and 83 are respectively the image pickup element drive circuit 13 and the variable amplifier circuit 1.
6, input to the diaphragm drive circuit 15.

On the other hand, the contrast calculation circuit 81 calculates a value obtained by dividing the background average photometric value by the subject average photometric value as the contrast between the subject and the background, and the backlight judgment circuit 1
Output to 2.

The backlight determination circuit 12 shown in FIG. 7 determines backlight / over-forward light according to the contrast value output from the arithmetic circuit 18. In general, when the subject is backlit, the subject is in a “black sunken state”, so that the subject average photometric value is small and the contrast value is large.

On the other hand, in the case of over-forward light, on the contrary, the subject becomes brighter than the background, so that the subject average photometric value becomes large and the contrast value becomes small. Therefore, when the contrast is "1", that is, when the brightness distribution of the subject and the background are equal, it is determined to be "backlit state" when it is 1 or more and "over-forward illumination state" when it is 1 or less. Then, information about whether it is a backlit state or an over-forwarded state,
Output to the sampling detection circuit 17.

Next, a method of determining the object photometric area using the boundary value in the sampling detection circuit 17 will be described.

FIG. 9 is a block diagram of the sampling circuit 17. Reference numerals 95, 96 and 97 are input terminals, and 98 is an output terminal.

Reference numeral 91 denotes a small block sampling signal detection circuit 91 which divides a rectangular object photometric area on the screen into blocks of "32 pixels x 16 lines" as in the case of the processing in the first embodiment. For each block, detect the photometric value,
Output.

Boundary value calculation circuit 92
Detect the peak value in the rectangular subject metering area, for example,
It outputs half the peak value. This half of the peak value is used as the boundary value. The half value of the peak value is an example of the boundary value.

The principle of discrimination using boundary values is shown in FIG.
This will be described with reference to 0.

As shown in FIG. 10A, in "backlight", the "background" is usually bright and the "subject" is blackened, so the brightness of the subject is the peak of the rectangular subject photometric region. It is likely to be less than half the value.

In FIG. 10A, since the peak value of the rectangular object photometric area is "120", half of the peak value is "6".
0 ". In addition, the photometric value in an arbitrary block area for the subject is “20”, which is a value smaller than half the peak value “60”.

On the contrary, as shown in FIG.
Since the "background" is dark and the "subject" is bright during overexposure, the brightness of the subject is likely to be half or more of the peak value of the rectangular subject photometric region.

In FIG. 10B, since the peak value of the rectangular object photometric area is "120", half of the peak value is "6".
0 ". In addition, the photometric value in an arbitrary block area for the subject is “80”, which is a value larger than half the peak value “60”.

In the example shown in FIGS. 10A and 10B, the boundary value is "60" which is half the peak value "120" of the rectangular object photometric area.

Now, the subject judging circuit 93 has the input terminal 9
The judgment result of the backlight judgment circuit 12 inputted via 7 is
If it is determined that the light is in the backlight state, the photometric value output by the small block sampling signal detection circuit 91 is compared with the boundary value, and the photometric value is output only when the photometric value is equal to or less than the boundary value.

If it is determined that the light is over-forward,
The photometric value is output only when the photometric value output by the small block sampling signal detection circuit 91 is equal to or greater than the boundary value.

Then, the integrating circuit 94 adds the input photometric values and outputs the addition result via the output terminal 98.

By configuring the sampling detection circuit 17 as described above, even in the case of backlight / over-forward light,
It is possible to prevent the influence of areas other than the subject in the rectangular subject photometric region and detect an appropriate average photometric value of the subject. Further, the boundary value calculation circuit 92 may find an average value in the subject photometric area, and use the value as a boundary value to perform similar processing.

In the present embodiment, as in the first embodiment, since exposure control is performed in real time using the photometric value obtained from the area where the subject is present, the brightness of the subject is always kept at an appropriate level. It is possible to realize the exposure control for maintaining the exposure. Further, since not only the shutter speed but also the diaphragm and the amplification degree are variable to perform the exposure control, the exposure control with a wide control range is possible.

Further, in the second embodiment, the control circuit 7,
The control performed by the three circuits of the backlight determination circuit 12 and the arithmetic circuit 18 is preferably configured to be controlled by using the microcomputer 19 and software for operating the same. That is, it is possible to realize the configuration for performing the above-described processing while suppressing an increase in cost and device size by the processing by software.

[0091]

As described above, according to the present invention, for example,
By determining whether or not each block forming the subject photometric area approximated by a rectangle is on the subject, the photometric value for the subject can be detected, and the accuracy of exposure control is improved. Therefore, it is possible to prevent the performance of the exposure control from deteriorating in the case of backlighting and over-forwarding, and to perform the exposure control that always brings the subject to an appropriate brightness.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment according to the present invention.

FIG. 2 is an explanatory diagram of a subject photometry area and a background photometry area.

FIG. 3 is an explanatory diagram illustrating a concept of a subject photometric area according to a shape in the first embodiment.

FIG. 4 is a configuration diagram of a sampling detection circuit.

FIG. 5 is an explanatory diagram of a concept of subject determination in a rectangular subject photometric region in the first embodiment.

FIG. 6 is a configuration diagram of an arithmetic circuit.

FIG. 7 is a configuration diagram of a second embodiment according to the present invention.

FIG. 8 is a configuration diagram of an arithmetic circuit according to a second embodiment.

FIG. 9 is a configuration diagram of a sampling detection circuit according to a second embodiment.

FIG. 10 is an explanatory diagram of a method of determining a subject existing block using a boundary value.

[Explanation of symbols]

1 ... Lens, 2 ... Image sensor drive circuit, 3 ... Image sensor, 4
... Amplification circuit, 5 ... Camera signal processing circuit, 6 ... Subject extraction circuit, 7 ... Control circuit, 8 ... Variable area signal detection circuit, 9 ...
Sampling detection circuit, 10 ... Arithmetic circuit, 11 ... Output terminal, 12 ... Backlight determination circuit, 13 ... Image sensor drive circuit, 1
4 ... Aperture, 15 ... Aperture drive circuit, 16 ... Variable amplification circuit,
17 ... Sampling detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Miyagi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Hitachi, Ltd. Multimedia System Development Division (72) Inventor Toshiro Kinugasa Yoshida, Totsuka-ku, Yokohama-shi, Kanagawa 292, Machi Co., Ltd. Hitachi, Ltd. Multimedia system development headquarters

Claims (7)

[Claims] 1. An image sensor for photoelectrically converting incident light to output an image signal, and a signal processing means for generating a video signal including a color difference signal and a luminance signal from the image signal output by the image sensor. A subject extraction unit that outputs information on a subject photometric region that is a region having a predetermined shape including the subject based on the video signal, and a region other than the subject region with reference to the video signal and the subject photometric region. A variable area signal detecting unit for detecting a background photometric value, and referring to the video signal and the subject photometric area, divides the subject photometric area into blocks of a predetermined size and adds a luminance signal to a block in which the subject exists. Then, the sampling detection means for outputting the added photometric value, the background photometric value output by the variable area signal detection means, and the sampler And a calculation unit that calculates an exposure control amount based on the photometric value output by the detection unit; and an exposure control unit that controls the exposure amount of the image sensor based on the exposure control amount calculated by the calculation unit. Imaging device. 2. The sampling detection means according to claim 1, wherein the subject photometric area is divided into blocks of a predetermined size,
Corresponding to YC data sampling means for sampling color difference signals and luminance signals for each block and outputting as YC data, YC data output by the YC data sampling means, and subject photometric area output by the subject extracting means. Judging means for comparing the color difference signal and the luminance signal to judge whether or not a subject exists in each block, and an integrating means for adding the luminance signals of the blocks in which the judging means judges that the subject exists. And an imaging device configured to include. 3. The subject according to claim 1, wherein the calculation means refers to a luminance signal and an area of each block in which the subject exists, and calculates an average subject photometric value which is a photometric value per unit area for the subject. An average photometric value calculating means, a background average photometric value calculating means for calculating a background average photometric value which is a photometric value per unit area with respect to the background with reference to the background photometric value and area, the subject average photometric value and the background average photometric value An image pickup apparatus configured to include an exposure control amount calculation unit that calculates an exposure control amount based on a background average photometric value. 4. The calculation unit according to claim 1, further comprising: a background and a subject on the basis of a photometric value of the background output by the variable region signal detecting unit and a photometric value of the sampling detecting unit. Imaging having a function of calculating a contrast, and a state determination unit for determining whether the state is a backlit state or an over-forward state according to the contrast calculated by the calculation unit apparatus. 5. The sampling detection means according to claim 4, wherein the subject photometric area is divided into blocks of a predetermined size,
For each block, a luminance signal is sampled to detect a photometric value of the block, and a small block sampling signal detection unit and a video signal output by the signal processing unit are referred to to determine the Of these, two values are determined in advance by comparing the peak value of the photometric value with a boundary value calculating means for calculating the boundary value and the photometric value of each block and the boundary value. In the case where there is a relationship, as a block in which the subject exists, it is configured to have a subject determining unit that outputs a photometric value for the block and an integrating unit that adds the photometric values output by the subject determining unit. Imaging device. 6. The predetermined relationship according to claim 5, wherein the photometric value of each block is larger than the boundary value,
Alternatively, the photometric value of each block is either smaller than the boundary value, the subject determination means, by referring to the predetermined relationship,
An image pickup apparatus, which detects a block in which an object exists and outputs a photometric value for the block. 7. The subject according to claim 4, wherein the calculating means calculates a subject average photometric value which is a photometric value per unit area for the subject by referring to a luminance signal and an area of each block in which the subject exists. An average photometric value calculating means, a background average photometric value calculating means for calculating a background average photometric value which is a photometric value per unit area with respect to the background with reference to the background photometric value and area, the subject average photometric value and the background average photometric value An exposure control amount calculation unit that calculates an exposure control amount based on the background average photometric value, and a contrast unit that calculates the contrast between the subject and the background based on the subject average photometric value and the background average photometric value. An imaging device configured to have.