Patent Description:
A technology is known in which, during a laparoscopic surgery performed using a rigid endoscope, autofocusing of an imaging device is controlled by excluding the body parts that are not appropriate as the focus position of the imaging device, see for example <CIT>.

In <CIT>, autofocus control is prevented from being performed at a body part that is not appropriate for focusing. Hence, an inappropriate body part is prevented from coming into focus. However, when the focus is on any one of a plurality of unexcluded body parts, there is a possibility that the body part in focus is not the operator-desired body part. This issue is not limited to autofocusing control, but is identical across the overall imaging auto-control such as automatic gain control and automatic white balance control.

It is an objective of the application concerned to provide an imaging control device, an endoscope system, and an imaging control method that enable performing imaging auto-control by setting the operator-desired body part as the photometric area.

In accordance with the present invention, an imaging control device, an endoscope system and a computer-implemented imaging control method as set forth in Claims <NUM>, <NUM> and <NUM> is provided. Preferred embodiments of the invention are claimed in the dependent claims.

According to the application concerned, it becomes possible to perform imaging auto-control by setting the operator-desired body part as the photometric area.

An exemplary embodiment of the application concerned is described below in detail with reference to the accompanying drawings. However, the application concerned is not limited by the embodiment. Moreover, when a plurality of embodiments is present, it is possible to have combinations of the embodiments. In the embodiment described below, identical constituent elements are referred to by the same reference numerals, and their explanation is not repeatedly given.

Explained below with reference to <FIG> is an endoscope system according to the embodiment. <FIG> is a diagram that schematically illustrates an exemplary configuration of the endoscope system according to the embodiment.

As illustrated in <FIG>, an endoscope system <NUM> includes a rigid mirror <NUM>, a camera head <NUM>, a CCU (Camera Control Unit) <NUM>, and a display device <NUM>. The endoscope system <NUM> obtains in-vivo images using the rigid mirror <NUM> and the camera head <NUM>. For example, the endoscope system <NUM> is used by an operator such as a doctor during a laparoscope surgery.

The rigid mirror <NUM> has an elongated tubular shape and is rigid in nature. The rigid mirror <NUM> is inserted into the body of a patient. For example, the rigid mirror <NUM> is inserted into the abdominal region of a patient. The rigid mirror <NUM> is configured using a plurality of optical lenses <NUM>. At the front end thereof, the rigid mirror <NUM> includes a light source unit <NUM> that bombards a light supplied from a light source device (not illustrated). Thus, the light source unit <NUM> bombards a light into the body of the patient. The light bombarded by the light source unit <NUM> is collected by the optical lenses <NUM>. As a result, an optical image is generated. The optical image that is generated as a result of light collection by the optical lenses <NUM> is then output to the camera head <NUM>. Meanwhile, in the present embodiment, although the endoscope system <NUM> includes the rigid mirror <NUM>, it can alternatively include a flexible mirror as the endoscope.

The camera head <NUM> performs imaging with respect to the optical image obtained from the rigid mirror <NUM>, and outputs the imaging result. The camera head <NUM> performs imaging with respect to the optical image, which is formed as a result of light collection in the rigid mirror <NUM>, under the control of the CCU <NUM>; and outputs an imaging signal. The camera head <NUM> and the CCU <NUM> are connected by a cable <NUM>. Thus, the camera head <NUM> outputs the imaging signal to the CCU <NUM> via the cable <NUM>. The camera head <NUM> can also be called an imaging device. Regarding a configuration of the camera head <NUM>, the explanation is given later.

The CCU <NUM> comprehensively controls the camera head <NUM> and the display device <NUM>. The CCU <NUM> processes the imaging signal that is input from the camera head <NUM> via the cable <NUM>, and generates an image signal. Then, the CCU <NUM> outputs the image signal to the display device <NUM>. As a result, an image gets displayed in the display device <NUM>. The CCU <NUM> and the display device <NUM> are connected by a cable <NUM>. Thus, the CCU <NUM> outputs the image signal to the display device <NUM> via the cable <NUM>. The CCU <NUM> can also be called an imaging control device. Regarding a configuration of the CCU <NUM>, the explanation is given later.

The display device <NUM> displays images. For example, based on an image signal input from the CCU <NUM>, the display device <NUM> displays a biological image of the patient. The display device <NUM> is a display such as a liquid crystal display (LCD) or an organic EL (Organic Electro-Luminescence) display.

In the present embodiment, imaging auto-control is performed based on the changes occurring in the luminance value of a taken image that is taken during a medical procedure. For example, when there is a movement of a procedure tool (for example, a surgical knife), there a change in the concerned portion. Particularly, a metallic procedure tool reflects the illumination light coming from the light source unit <NUM>, thereby resulting in an increase in the luminance value. In that regard, the operator can use the illumination light and the procedure tool to temporarily and intentionally reflect the light so as to create a location within a specific region inside the body at which the luminance value becomes equal to or greater than a predetermined threshold value, and hence can specify the location on which attention is to be focused during the procedure. In the present embodiment, the location having the luminance value to be equal to or greater than the threshold value is determined to be the region on which the operator wishes to focus attention, and optimum imaging auto-control is performed with respect to that region.

Explained below with reference to <FIG> is an exemplary configuration of the imaging device according to the embodiment. <FIG> is a block diagram illustrating an exemplary configuration of the imaging device according to the embodiment.

The camera head <NUM> includes an optical lens <NUM>, an imaging device <NUM>, a driving unit <NUM>, a signal processing unit <NUM>, and a communication unit <NUM>.

The optical lens <NUM> can be configured using one or more lenses. The optical lens <NUM> can also serve as the last-stage lens of the rigid mirror <NUM>. The optical lens <NUM> is configured to be movable along the light axis. As a result of being movable along the light axis, the optical lens <NUM> is equipped with a zooming function for varying the angle of view and a focusing function for varying the focal position. An optical image passes through the optical lens <NUM> and gets input to the imaging device <NUM>.

The imaging device <NUM> takes images of a photographic subject under the control of the driving unit <NUM>. The imaging device <NUM> receives the optical image formed by the optical lens <NUM>, and converts the optical image into an electrical signal. For example, the imaging device <NUM> performs photoelectric conversion of the received optical image to convert it into an electrical signal (analog signal), and outputs the electrical signal to the signal processing unit <NUM>. The imaging device <NUM> can be implemented using, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor).

The driving unit <NUM> controls the entire camera head <NUM> according to an operation signal corresponding to an operation input by the user via an operating unit (not illustrated), and according to a driving signal received from the CCU <NUM>. For example, the driving unit <NUM> controls the zooming function and the focusing function of the optical lens <NUM>, and varies the magnification and the focal point of the taken image obtained by the imaging device <NUM>.

The signal processing unit <NUM> performs a variety of signal processing with respect to the signal received from the imaging device <NUM>. For example, the signal processing unit <NUM> performs A/D (Analog/Digital) conversion with respect to the signal received from the imaging device <NUM>, and generates an imaging signal. Then, the signal processing unit <NUM> outputs the generated imaging signal to the communication unit <NUM>.

The driving unit <NUM> and the signal processing unit <NUM> are implemented when, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) execute a program, which is stored in a memory unit (not illustrated), using a RAM as the work area. Alternatively, the driving unit <NUM> and the signal processing unit <NUM> can be implemented using an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). Still alternatively, the driving unit <NUM> and the signal processing unit <NUM> can be implemented using a combination of software and hardware.

The communication unit <NUM> sends a variety of information to and receives a variety of information from the CCU <NUM>. For example, the communication unit <NUM> converts the imaging signal, which is received from the signal processing unit <NUM>, into a predetermined signal format to be output to the CCU <NUM>. Then, the signal processing unit <NUM> outputs the imaging signal, which has been converted into a predetermined signal format, to the CCU <NUM>. Moreover, the communication unit <NUM> receives, from the CCU <NUM>, a driving signal meant for controlling the zooming function and the focusing function of the optical lens <NUM>.

Explained below with reference to <FIG> is an exemplary configuration of the CCU according to the embodiment. <FIG> is a block diagram illustrating an exemplary configuration of the CCU according to the embodiment.

The CCU <NUM> includes a first communication unit <NUM>, a second communication unit <NUM>, and a control unit <NUM>. The CCU <NUM> is a control device that comprehensively controls the camera head <NUM> and the display device <NUM>.

The first communication unit <NUM> sends a variety of information to and receives a variety of information from the camera head <NUM>. For example, the first communication unit <NUM> receives an imaging signal that is input from the camera head <NUM> via the cable <NUM>. Then, the first communication unit <NUM> outputs the imaging signal, which is received from the camera head <NUM>, to the control unit <NUM>. Moreover, the first communication unit <NUM> sends a driving signal, which is meant for controlling the driving of the camera head <NUM>, to the camera head <NUM> via the cable <NUM>.

The second communication unit <NUM> sends a variety of information to and receives a variety of information from the display device <NUM>. For example, the second communication unit <NUM> sends an imaging signal to the display device <NUM> via the cable <NUM>.

The control unit <NUM> controls, for example, the imaging operation of the camera head <NUM> and a variety of processing related to the display operation of the display device <NUM>. For example, the control unit <NUM> generates a driving signal meant for controlling the driving of the camera head <NUM>. In the present embodiment, the control unit <NUM> generates a driving signal meant for bringing the operator-desired body part into focus.

The control unit <NUM> is implemented when a CPU or an MPU executes a program, which is stored in a memory unit (not illustrated), using a RAM as the work area. Alternatively, the control unit <NUM> can be implemented using an integrated circuit such as an ASIC or an FPGA. Still alternatively, the control unit <NUM> can be implemented using a combination of software and hardware.

The control unit <NUM> includes a region dividing unit <NUM>, a luminance value calculating unit <NUM>, a region identifying unit <NUM>, a photometric area deciding unit <NUM>, a signal processing unit <NUM>, a display control unit <NUM>, and a communication control unit <NUM>.

The region dividing unit <NUM> performs a division operation with respect to a taken image that is received by the first communication unit <NUM>. For example, the region dividing unit <NUM> divides the taken image, which is received by the first communication unit <NUM>, into a plurality of regions.

<FIG> is a diagram for explaining the operation of dividing a taken image into regions. With reference to <FIG>, the direction parallel to the X axis represents the horizontal direction, and the direction parallel to the Y axis represents the vertical direction. In <FIG>, a taken image IM is illustrated. The region dividing unit <NUM> divides the taken image IM into a plurality of regions <NUM>. For example, the region dividing unit <NUM> divides the taken image IM into eight regions in the horizontal direction and eight regions in the vertical direction, and thus divides the taken image IM1 into <NUM> regions <NUM>. Herein, the division count of the taken image IM and the dimensions of the regions <NUM> set in the region dividing unit <NUM> are arbitrary, and can be arbitrarily changed according to the design.

Returning to the explanation with reference to <FIG>, the luminance value calculating unit <NUM> calculates the luminance value of the taken image. For example, the luminance value calculating unit <NUM> calculates the luminance value of each region in the taken image IM as obtained by division by the region dividing unit <NUM>. For example, the luminance value calculating unit <NUM> calculates the average luminance value of each region in the taken image IM as obtained by division by the region dividing unit <NUM>.

Based on the calculation result obtained by the luminance value calculating unit <NUM>, the region identifying unit <NUM> identifies a predetermined region. Thus, based on the calculation obtained by the luminance value calculating unit <NUM>, the region identifying unit <NUM> identifies the region <NUM> in which the luminance value exceeds a predetermined threshold value. The predetermined threshold value implies, for example, the luminance value at which what is called overexposure occurs. However, that is not the only possible case. Meanwhile, for example, if a plurality of regions <NUM> exceeds the predetermined threshold value, then the region identifying unit <NUM> can identify the regions <NUM> having the maximum luminance value. In the present embodiment, at the operator-desired location of attention inside the body of the patient, when the operator intentionally reflects the light using a procedure tool, the region identifying unit <NUM> identifies the regions in which the luminance value is equal to or greater than the predetermined threshold value.

The photometric area deciding unit <NUM> decides on the photometric area. The photometric area can be the operator-desired range of attention. The photometric area deciding unit <NUM> decides on the photometric area based on the regions <NUM> that are identified by the region identifying unit <NUM> to have the luminance value exceeding the predetermined threshold value. If the period of time for which the average luminance value of the region identified by the region identifying unit <NUM> is equal to or greater than a threshold value is equal to or greater than a first predetermined period and is smaller than a second predetermined period, then the photometric area deciding unit <NUM> decides that the region identified by the region identifying unit <NUM> represents a new photometric area. The first predetermined period is, for example, approximately equal to a few seconds. However, that is not the only possible case. The second predetermined period is, for example, approximately equal to few tens of seconds. However, that is not the only possible case. More particularly, the period of time equal to or greater than the first predetermined period and smaller than the second predetermined period is large enough to enable determination of the fact that the operator is intentionally reflecting the light using a procedure tool. In the example illustrated in <FIG>, the photometric area deciding unit <NUM> decides on, for example, a photometric area <NUM>. Herein, the photometric area <NUM> is a region equivalent to nine regions <NUM>. As illustrated in <FIG>, the photometric area is not limited to be the smallest unit such as a single region <NUM>, and can be a region such as the photometric area <NUM> formed by a plurality of regions <NUM> representing the smallest units. Moreover, according to the features of the detection target, the photometric area <NUM> can appropriately change to be horizontally long or vertically long.

The signal processing unit <NUM> performs a variety of processing with respect to the imaging signal received from the first communication unit <NUM>. The signal processing unit <NUM> performs imaging auto-control such as autofocusing, automatic gain control, and automatic white balance control. Moreover, the signal processing unit <NUM> can perform other known types of processing with respect to the photometric area <NUM> decided by the photometric area deciding unit <NUM>.

In the autofocusing control, for example, in the taken image IM, the signal processing unit <NUM> extracts, for each region <NUM>, the high-range component and the midrange component of the imaging signal. For example, the signal processing unit <NUM> calculates the optimum driving state of the optical lens <NUM> in which the ratio of the high-range component and the midrange component, from among the imaging components of the photometric area <NUM> decided by the photometric area deciding unit <NUM>, is the highest. In the autofocusing control, the signal processing unit <NUM> outputs a driving signal meant for controlling the optical lens <NUM> in the optimum driving state. As a result, the optical lens <NUM> becomes able to bring the photometric area <NUM>, which is decided by the photometric area deciding unit <NUM>, into focus.

In the automatic gain control, for example, in the taken image IM, the signal processing unit <NUM> performs gain adjustment based on the average luminance value and the maximum luminance value of each region <NUM>. For example, the signal processing unit <NUM> applies gain to the imaging signal of the taken image IM in such a way that the photometric area <NUM>, which is decided by the photometric area deciding unit <NUM>, has the same luminance value as the target luminance value. As a result, an easy-to-view video level is achieved.

In the automatic white balance control, for example, in the taken image IM, the signal processing unit <NUM> calculates the RGB components in each region <NUM>. For example, with respect to an achromatic photographic subject included in the photometric area decided by the photometric area deciding unit <NUM>, the signal processing unit <NUM> achieves the optimum white balance by applying gain in such a way that the RGB components have the same level to each other.

The display control unit <NUM> controls the display device <NUM>. The display control unit <NUM> displays, for example, the taken image IM in the display device <NUM>. For example, in the display device <NUM>, the display control unit <NUM> displays the taken image IM that has been subjected to imaging auto-control.

The communication control unit <NUM> controls the first communication unit <NUM> for controlling the communication between the camera head <NUM> and the CCU <NUM>. For example, the communication control unit <NUM> controls the first communication unit <NUM> and sends, to the camera head <NUM>, a driving signal meant for controlling the driving state of the optical lens <NUM>.

Moreover, the communication control unit <NUM> controls the second communication unit <NUM> for controlling the communication between the CCU <NUM> and the display device <NUM>. For example, the communication control unit <NUM> controls the second communication unit <NUM> and sends an imaging signal regarding the taken image to be displayed in the display device <NUM>.

Explained below with reference to <FIG> is a CCU control operation according to the embodiment. <FIG> is a flowchart for explaining an exemplary flow of the CCU control operation according to the embodiment.

The control unit <NUM> divides the taken image into a plurality of regions (Step S10). More particularly, the region dividing unit <NUM> divides the taken image IM into a plurality of regions <NUM> as illustrated in <FIG>. Then, the system control proceeds to Step S12.

The control unit <NUM> calculates the luminance value of each region (Step S12). More particularly, in the taken image IM, the luminance value calculating unit <NUM> calculates the average luminance value of each region <NUM>. <FIG> is a diagram that visually illustrates the average luminance values in the taken image IM. In <FIG> are illustrated the region-by-region luminance values. As illustrated in <FIG>, as a result of calculating the average luminance value of each region <NUM>, the luminance value calculating unit <NUM> can obtain luminance value information <NUM> in which the luminance values are visually illustrated in the form of asperity. Then, the system control proceeds to Step S14.

The control unit <NUM> determines whether or not any region has the luminance value to be equal to or greater than a threshold value (Step S14). More particularly, based on the luminance value of each region <NUM> as calculated by the luminance value calculating unit <NUM>, the region identifying unit <NUM> determines whether or not any region <NUM> has the luminance value equal to or greater than a predetermined luminance value.

Explained below with reference to <FIG> is the condition in which a luminance value becomes equal to or greater than a predetermined threshold value. <FIG> is a diagram for explaining the condition in which a luminance value becomes equal to or greater than a predetermined threshold value. As illustrated in <FIG>, a reflecting object <NUM> is captured in the taken image IM. In the present embodiment, the reflecting object <NUM> represents a procedure tool such as a surgical knife used by the operator. <FIG> is a diagram that visually illustrates the luminance values in the taken image IM in which a reflecting object is captured. In <FIG> is illustrated luminance value information <NUM> indicating the region-by-region luminance values. The luminance value information <NUM> contains a high-luminance region 82a in which the luminance value is prominently high due to the reflection from the reflecting object <NUM>. For example, the region identifying unit <NUM> detects the high-luminance region 82a based on the luminance value information <NUM>, and identifies it as the region having the luminance value equal to or greater than a predetermined threshold value. Thus, if a region having the luminance value to be equal to or greater than a threshold value is determined to be present (Yes at Step S14), then the system control proceeds to Step S16. On the other hand, if a region having the luminance value to be equal to or greater than a threshold value is determined to be absent (No at Step S14), then the system control proceeds to Step S28.

If the determination at Step S14 indicates Yes, then the control unit <NUM> determines whether or not, in the identified region, the duration for which the luminance value is equal to or greater than the threshold value is equal to or greater than the first predetermined period (Step S16). More particularly, the photometric area deciding unit <NUM> uses a counter (not illustrated) to determine whether or not the duration for which the luminance value is equal to or greater than the threshold value is equal to or greater than the first predetermined period. If the duration for which the luminance value is equal to or greater than the threshold value is determined to be equal to or greater than the first predetermined period (Yes at Step S16), then the system control proceeds to Step S18. On the other hand, if the duration for which the luminance value is equal to or greater than the threshold value is determined not to be equal to or greater than the first predetermined period (No at Step S16), then the system control proceeds to Step S28.

If the determination at Step S16 indicates Yes, then the control unit <NUM> determines whether or not, in the identified region, the duration for which the luminance value is equal to or greater than the threshold value is smaller than the second predetermined period (Step S18). More particularly, the photometric area deciding unit <NUM> uses a counter (not illustrated) to determine whether or not the duration for which the luminance value is equal to or greater than the threshold value is smaller than the second predetermined period. If the duration for which the luminance value is equal to or greater than the threshold value is determined to be smaller than the second predetermined period (Yes at Step S18), then the system control proceeds to Step S20. On the other hand, if the duration for which the luminance value is equal to or greater than the threshold value is determined not to be smaller than the second predetermined period (No at Step S18), then the system control proceeds to Step S28.

If the determination at Step S18 indicates Yes, then the control unit <NUM> decides on the photometric area (Step S20). More particularly, the photometric area deciding unit <NUM> decides that the region identified by the region identifying unit <NUM> at Step S14 represents the new photometric area. Then, the system control proceeds to Step S22.

The control unit <NUM> changes the photometric area (Step S22). More particularly, the photometric area deciding unit <NUM> changes the present photometric area to the new photometric area decided at Step S20.

Explained below with reference to <FIG> is a method for changing the photometric area. <FIG> is a diagram for explaining a method for changing the photometric area. In the normal auto-gain control, if momentary changes in the signal are followed, then the brightness of the image undergoes severe changes and the video becomes more obscure. Hence, the photometric area is changed while keeping a time constant of a few seconds to few tens of seconds. In the present embodiment, the region having the luminance value equal to or greater than the threshold value is used as the index of the target coordinates of the photometric area. More particularly, as illustrated in <FIG>, the photometric area deciding unit <NUM> changes the present photometric area <NUM> to a photometric area <NUM> centered around the reflecting object <NUM>. As a result of performing such control, the movement of the photometric area intended for the practitioner or the assistant of the practitioner can be easily performed only by a small action using the procedure tool of the practitioner. Subsequently, the system control proceeds to Step S24.

The control unit <NUM> performs imaging auto-control (Step S24). More particularly, with respect to the photometric area changed at Step S22, the signal processing unit <NUM> performs imaging auto-control such as autofocusing, automatic gain control, and automatic white balance control. Then, the system control proceeds to Step S26.

The control unit <NUM> displays an image in the display device <NUM> (Step S26). More particularly, the display control unit <NUM> displays, in the display device <NUM>, the taken image that has been subjected to imaging auto-control by the signal processing unit <NUM> at Step S24. Then, the system control proceeds to Step S30.

If the determination Step S14 indicates No, or if the determination Step S16 indicates No, or if the determination Step S18 indicates No, then the control unit <NUM> retains the present photometric area (Step S28). More particularly, the photometric area deciding unit <NUM> retains the present photometric area without changing it. More particularly, when the determination Step S16 indicates No, that is, when the duration for which the luminance value is equal to or greater than the threshold value is smaller than the first predetermined period, the photometric area deciding unit <NUM> retains the present photometric area under the assumption that the reflection is not intentionally caused by the operator. When the determination Step S18 indicates No, that is, when the duration for which the luminance value is equal to or greater than the threshold value is equal to or greater than the second predetermined period, the photometric area deciding unit <NUM> retains the present photometric area under the assumption that the reflection is originally present regardless of the intention of the operator. Then, the system control proceeds to Step S24.

The control unit <NUM> determines whether or not to end the control operation (Step S30). More particularly, when an operation for ending the control operation is received and when an operation for switching off the power source is received, the control unit <NUM> determines to end the control operation. If it is determined to end the control operation (Yes at Step S30), then the operations illustrated in <FIG> are ended. On the other hand, if it is determined not to end the control operation (No at Step S30), then the system control returns to Step S10.

As explained above, in the present embodiment, in a taken image, a certain range centered around a region having the luminance value to be equal to or greater than a threshold value is set as the photometric area to be subjected to imaging auto-control. As a result, in the present embodiment, the most suitable image processing can be performed with respect to the location on which the operator is focusing attention. In the present embodiment, the operator can move a procedure tool for reflecting the light, so that the photometric area can be changed with ease.

Moreover, in the present embodiment, the photometric area can be retained with the aim of ensuring that, once the procedure is completed, the light does not get reflected from the procedure tool. Thus, in the present embodiment, as a result of fixing the photometric area to the location of performing procedure, the post-procedure condition becomes easy to observe.

In the present embodiment, it is possible to make use of the features of the photographing conditions of a laparoscopic surgery in which a rigid endoscope is used. As a result, in the present embodiment, during a laparoscopic surgery in which a rigid endoscope is used, the photometric area can be set at the location on which the operator is focusing attention, and optimum imaging auto-control can be performed.

Herein, although the application concerned is described with reference to the abovementioned embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth. Moreover, the constituent elements explained above can be appropriately combined. Furthermore, the constituent elements can be deleted, substituted, or modified without departing from the scope of the embodiment described above.

Claim 1:
An imaging control device (<NUM>) comprising:
a region dividing unit (<NUM>) configured to divide a taken image into a plurality of regions;
a luminance value calculating unit (<NUM>) configured to calculate an average luminance value of each region obtained by division by the region dividing unit (<NUM>);
a region identifying unit (<NUM>) configured to identify a region in which the average luminance value calculated by the luminance value calculating unit (<NUM>) is equal to or greater than a predetermined threshold value;
a photometric area deciding unit (<NUM>) configured to,
when a period of time for which the average luminance value of the region identified by the region identifying unit (<NUM>) is equal to or greater than the threshold value is equal to or greater than a first predetermined period and smaller than a second predetermined period, decide that the region identified by the region identifying unit (<NUM>) represents a new photometric area; and
when the period of time is equal to or greater than the second predetermined period, retain a present photometric area; and
a signal processing unit (<NUM>) configured to perform imaging auto-control with respect to the new photometric area decided by the photometric area deciding unit (<NUM>), the imaging auto-control including autofocusing, automatic gain control, and automatic white balance control.