JP2017083705A - Imaging device and imaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device and an imaging method capable of suppressing moire without largely reducing the image quality of a photographed image.SOLUTION: A document camera 50 comprises: an imaging part 90 including a zoom adjustment part 96 that changes the optical zoom magnification and a focus adjustment part 97 that performs focus adjustment; a correction amount derivation part 70c that derives the amount of correction in focus adjustment corresponding to the optical zoom magnification changed by the zoom adjustment part 96; and an image processing part 84 that performs focus adjustment by controlling the focus adjustment part 97 on the basis of the amount of correction derived by the correction amount derivation part 70c.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an imaging apparatus and an imaging method.

  Conventionally, when a display that displays an image is captured by a camera, it is known that moire occurs in the captured image (see, for example, Patent Document 1). This type of phenomenon is particularly likely to occur when the display is focused (focused). In order to suppress the occurrence of moire, the apparatus described in Patent Document 1 adjusts the back focus by moving the distance between the lens system and the image sensor after performing focusing, so to speak, the operation of shifting the in-focus state.

JP 2009-156857 A

When adjusting the in-focus state in order to suppress moire as in the device described in Patent Document 1, if the adjustment amount in the in-focus state is excessive, the captured image is blurred and the image quality is degraded. There was a problem.
The present invention has been made in view of the above problems, and an object thereof is to provide an imaging apparatus and an imaging method capable of suppressing moire without significantly reducing the image quality of a captured image.

In order to achieve the above object, an imaging apparatus according to the present invention corresponds to a zoom adjustment unit that changes an optical zoom magnification, an imaging unit that includes a focus adjustment unit that performs focus adjustment, and an optical zoom magnification of the zoom adjustment unit. A correction amount deriving unit that derives a correction amount for focus adjustment, and a focus control unit that controls the focus adjustment unit based on the correction amount derived by the correction amount deriving unit and performs focus adjustment. An imaging device that is characterized.
According to the present invention, since the focus state is adjusted in accordance with the optical zoom magnification, moire can be suppressed without significantly reducing the image quality of the captured image.

In the imaging device, the present invention further includes a storage unit that stores correction amount information that defines a relationship between the optical zoom magnification of the zoom adjustment unit and the correction amount, and the correction amount derivation unit includes the storage unit. The correction amount of the focus adjustment corresponding to the optical zoom magnification of the zoom adjustment unit is derived based on the correction amount information stored by the zoom adjustment unit.
According to the present invention, the information that defines the relationship between the optical zoom magnification and the correction amount is stored, and the correction amount for focus adjustment is derived using this information, so that the focus state can be quickly and appropriately adjusted.

In the imaging apparatus according to the aspect of the invention, the storage unit may associate the optical zoom magnification of the zoom adjustment unit with the information for obtaining the correction amount or the correction amount in a table format including the correction amount. Storing information.
According to the present invention, it is possible to quickly derive an appropriate focus adjustment correction amount corresponding to the optical zoom magnification and adjust the focus state.

According to the present invention, in the imaging apparatus, the storage unit includes a second optical having a higher magnification than the first optical zoom magnification compared to a correction amount corresponding to the first optical zoom magnification of the zoom adjustment unit. The correction amount information that stores a correction amount with a small correction amount corresponding to the zoom magnification is stored.
According to the present invention, it is possible to appropriately adjust the focus state corresponding to the optical zoom magnification, and to suppress the deterioration of the image quality of the captured image.

In the imaging apparatus, the present invention further includes a mode switching unit that performs switching between the first operation mode and the second operation mode, and the focus control unit derives the correction amount in the first operation mode. The focus adjustment is performed based on the correction amount derived by the unit, and the focus adjustment is performed without using the correction amount derived by the correction amount deriving unit in the second operation mode.
According to the present invention, by switching the operation mode, it is possible to select a state in which focus adjustment for suppressing moire is executed and a state in which the adjustment is not executed. For example, when capturing a display that displays an image, moiré of the captured image can be suppressed by switching to the first operation mode. Also, for example, by switching to the second operation mode when imaging other subjects, a high-quality captured image that is in focus can be obtained.

In the imaging apparatus according to the aspect of the invention, the focus control unit may correct the correction amount when the operation mode of the imaging apparatus is switched from the second operation mode to the first operation mode by the mode switching unit. Focus adjustment is performed based on the correction amount derived by the deriving unit.
According to the present invention, when the operation mode is switched, the focus state is adjusted so as to suppress moire, so that the operability can be improved.

In the imaging apparatus, the first operation mode is a mode suitable for imaging a display screen, and the second operation mode is an operation mode different from the first operation mode. And
According to the present invention, the first operation mode suitable for imaging the display screen and the second operation mode are switched and executed, and the focus adjustment is executed based on the correction amount in the first operation mode. For this reason, focus adjustment can be performed based on the correction amount in the first operation mode suitable for a situation in which moiré is likely to occur, and generation of moiré can be suppressed. When there is little concern about the occurrence of moire, for example, the second operation mode can be executed to obtain a high-quality captured image.

Further, the present invention is characterized in that the imaging apparatus includes an operation unit that receives an operation, and the focus control unit performs a focus adjustment based on an operation on the operation unit.
According to the present invention, the focus adjustment for suppressing moire can be executed as necessary, and the operability can be improved.

In order to achieve the above object, the imaging method of the present invention uses an imaging unit capable of changing the optical zoom magnification and adjusting the focus, deriving a correction amount of focus adjustment corresponding to the optical zoom magnification, and deriving the correction amount. In this case, the focus adjustment is performed based on the image, and the imaging is performed after the focus adjustment.
According to the present invention, since the focus state is adjusted in accordance with the optical zoom magnification, moire can be suppressed without significantly reducing the image quality of the captured image.

Explanatory drawing which shows schematic structure of a projection system. The functional block diagram of a projector and a document camera. The principal part top view of an operation panel. The schematic diagram which shows an example of the correction amount information which a document camera memorize | stores. Explanatory drawing which shows the characteristic of correction amount information. The flowchart which shows operation | movement of a document camera.

Embodiments of the present invention will be described below based on examples with reference to the drawings.
FIG. 1 is an explanatory diagram showing a schematic configuration of a projection system 100 as an embodiment to which the present invention is applied.
The projection system 100 includes a projector 10 and four image input devices connected to the projector 10. In the present embodiment, a document camera 50, a personal computer 201, a video tape recorder (VTR) 202, and a DVD (Digital Versatile Disk) player 203 will be described as image input devices. These image input devices provide an image input source to the projector 10. The image input device is not particularly limited as long as it is a device that supplies an analog image signal or digital image data to the projector 10. In addition to the above devices, a television tuner device, a CATV (Cable television) set top box, a video game device, or the like may be used. In addition, the image input to the projector 10 by the image input device may be a still image or a moving image (video). In the following description, an example in which an image input device included in the projection system 100 inputs digital image data to the projector 10 will be described.

The projector 10 selects any one of the image input devices that are input sources as described later, and displays (projects) an image on the screen SC based on the selected input source.
Although FIG. 1 illustrates an example of floor installation in which the projector 10 is placed in front of the screen SC, the projector 10 may be installed by being suspended from the ceiling. In the present embodiment, the case where the projector 10 projects onto a flat screen SC is exemplified, but the projection target is not limited to the screen SC, and may be a flat surface such as a wall surface of a building, or may be a curved surface or an uneven surface. Good.

The document camera 50 is connected to the projector 10 via a USB cable 59.
The document camera 50 includes a base 52, a placement surface 54, an arm 56, a camera head 58, and an operation panel 60. The base 52 is a flat base that supports the document camera 50, and the upper surface of the base 52 is a placement surface 54 on which the subject T is placed.
The subject T is, for example, a sheet of paper or the like on which characters or pictures are drawn, or a bound book, but is not limited as long as it can be placed on the placement surface 54. The subject T may be, for example, a display having a liquid crystal display panel or an organic EL display panel, or may be an electronic device such as a tablet computer or a smartphone equipped with this type of display.

The arm 56 stands on the base 52, and a camera head 58 is fixed to the tip of the arm 56. The arm 56 may be fixed to the base 52, and a connecting portion that connects the arm 56 and the base 52 includes a rotation mechanism, and the arm 56 can be folded toward the base 52 by the rotation mechanism. It is good also as a structure.
The camera head 58 includes an imaging unit 90 (FIG. 2) that is supported by the arm 56 and faces the placement surface 54. The imaging unit 90 images the subject T placed on the placement surface 54.

The operation panel 60 is provided on the upper surface of the base 52, for example. As will be described later with reference to FIG. 3, the operation panel 60 includes a plurality of buttons (button type switches) operated by the user, and inputs an operation command to the document camera 50 by the user.
The document camera 50 receives a user's operation through the operation panel 60, images the subject T with the imaging unit 90 (FIG. 2) in response to the operation, and outputs image data based on the captured image to the projector 10.

FIG. 2 is a functional block diagram showing functional configurations of the projector 10 and the document camera 50.
The projector 10 includes a control unit 20, a storage unit 22, an operation unit 24, a USB interface (USB I / F) unit 26, an input interface (I / F) unit 28, an input source switching unit 30, an image processing unit 32, and A projection unit 34 is provided. Reference numeral 36 denotes a bus, which connects between the control unit 20 and each unit other than the projection unit 34, and the control unit 20 transmits and receives control data via the bus 36. The projector 10 also includes a remote control 38 that is operated by the user.

  The control unit 20 includes a CPU (Central Processing Unit) (not shown), and controls each unit of the projector 10 by executing a control program by the CPU. In addition to the CPU, the control unit 20 includes a ROM (Read Only Memory) (not shown) that stores a basic control program and setting data executed by the CPU in a nonvolatile manner, and a RAM (Random Access Memory) (not shown) that forms a work area of the CPU. (Not shown) may be provided.

  The storage unit 22 stores a control program executed by the control unit 20 and various data processed by the control unit 20. Examples of this type of program include a well-known USB module, USB class driver, and image display program.

The operation unit 24 is a functional unit that inputs an operation command from the user to the projector 10 and functions as a reception unit that receives a user operation. The operation unit 24 includes an operation panel (not shown) having switches and buttons operated by the user, a remote control light receiving unit (not shown) that receives an infrared signal transmitted from the remote control 38, and the like. The operation panel includes, for example, a power switch for turning on / off the power of the projector 10, an input source switching button (not shown) for switching an input source of an image displayed on the projector 10, and the like.
The remote control 38 includes various buttons including an input source switching button (not shown) for switching the input source of an image to be displayed on the projector 10, and transmits an infrared signal indicating the operated button. The operation unit 24 outputs data corresponding to the operation content on the operation panel and the remote control 38 to the control unit 20.

  The USB interface unit 26 is an interface that transmits and receives various data including control data and image data to and from an external device in conformity with USB (Universal Serial Bus). In the present embodiment, the document camera 50 is connected to the USB interface unit 26 by the USB cable 59.

  The input interface unit 28 includes an interface to which an external device is connected. The input interface unit 28 transmits / receives data including control data and image data to / from an external device. The input interface unit 28 may include an analog interface (not shown) to which analog image signals and analog audio signals are input. Specifically, the input interface unit 28 includes an RGB interface, a video interface, an S-video interface, and the like. Also good. In the present embodiment, a personal computer 201, a VTR 202, and a DVD player 203 are connected to the input interface unit 28, respectively. The input interface unit 28 may include an A / D converter that converts an analog signal input to the analog interface into digital data.

  The input source switching unit 30 selects one interface as an input source from the interfaces provided in the USB interface unit 26 and the input interface unit 28 under the control of the control unit 20.

The image processing unit 32 generates display image data for image display based on image data or video data input from the interface selected by the input source switching unit 30.
The projection unit 34 modulates the light emitted from the light source based on the light source (not shown) and the display image data generated by the image processing unit 32 to generate image light, and the image light emitted from the light modulation device. A projection optical system. The light source of the projection unit 34 is, for example, a xenon lamp, an ultra high pressure mercury lamp, an LED (Light Emitting Diode), or a laser light source. The light modulation device includes, for example, three transmissive liquid crystal panels corresponding to the three primary colors of RGB, and the light emitted from the light source is separated into three color lights of RGB, and each color light enters each corresponding liquid crystal panel. The liquid crystal panel of the light modulation device modulates the light incident from the light source, and the modulated color light is combined by a combining optical system such as a cross dichroic prism and emitted to the projection optical system. The projection optical system includes an optical component such as a lens, and images the image light modulated by the light modulation device on the screen SC.

  The document camera 50 includes a control unit 70, a storage unit 72, an operation unit 74, a USB interface (USB I / F) unit 76, an illumination unit 78, an illumination control unit 80, an image processing unit 84, a resolution conversion unit 86, and imaging. Part 90 is provided. Reference numeral 88 denotes a bus, which connects between the control unit 70 and each part of the document camera 50 excluding the operation panel 60, the illumination unit 78, and the imaging unit 90.

  The control unit 70 includes a microcomputer including a CPU, ROM or nonvolatile memory, RAM, a DSP (Digital Signal Processor), and the like. The control unit 70 executes a computer program stored in the storage unit 72 and controls each unit of the document camera 50. The storage unit 72 stores various programs executed by the control unit 70 and data processed by the control unit 70. For example, the storage unit 72 stores a known USB module, USB class driver, a program for controlling the imaging unit 90, and the like. In the present embodiment, the storage unit 72 stores correction amount information 72 a that is data for correcting the focus adjustment state of the imaging unit 90.

  The USB interface unit 76 is an interface for exchanging control data, image data, and the like with an external device in accordance with the USB standard. In this embodiment, the USB interface unit 76 is connected to the USB interface unit 26 of the projector 10. The USB interface unit 76 corresponds to a “communication unit” that is a component of the present invention.

  The illumination unit 78 is a light source such as an LED that irradiates the subject T with light, and is disposed on the camera head 58 (FIG. 1). The illumination control unit 80 controls turning on and off of the light source of the illumination unit 78 according to the control of the control unit 70. Moreover, the structure which can adjust the brightness | luminance of the light source with which the illumination part 78 is provided may be sufficient as the illumination control part 80. FIG.

  The imaging unit 90 includes an imaging lens 91 and an imaging element 92 made of a CCD (Charge Coupled Device), a CMOS (Complementary MOS), or the like. The imaging lens 91 is composed of a lens or a lens group, and constitutes an optical system that images the subject T. The lenses constituting the imaging lens 91 are movable along the optical axis AX. The imaging unit 90 includes a zoom adjustment unit 96 that changes the optical zoom magnification by moving the imaging lens 91, and a focus adjustment unit 97 that adjusts an in-focus state (focus) in the imaging element 92. The zoom adjustment unit 96 and the focus adjustment unit 97 include, for example, a stepping motor (not shown) that moves the imaging lens 91. The zoom adjustment unit 96 and the focus adjustment unit 97 include a servo motor and an actuator (not shown) that move the imaging lens 91, a sensor (not shown) that detects the position of the imaging lens 91, and the like. Also good. In addition, the imaging unit 90 includes an output circuit 95 that detects a signal from the imaging element 92, generates captured image data, and outputs the captured image data to the image processing unit 84. The zoom adjustment unit 96 and the focus adjustment unit 97 have a configuration for moving the imaging lens 91 in the direction of the optical axis AX. Here, when the imaging lens 91 includes a lens group including a plurality of lenses, the zoom adjustment unit 96 and the focus adjustment unit 97 may be configured to move the position of the entire lens group in the optical axis AX direction. However, a configuration in which some lenses constituting the lens group are moved may be used.

  The image processing unit 84 is connected to the imaging unit 90 and drives the imaging unit 90 in accordance with control data input from the control unit 70. The image processing unit 84 outputs a drive signal to the zoom adjustment unit 96 and the focus adjustment unit 97 to move the imaging lens 91. In addition, the image processing unit 84 performs image processing such as converting the captured image data output from the output circuit 95 into a form of image data that can be processed by the control unit 70, and sends the processed data to the control unit 70. Output.

  The control data input from the control unit 70 to the image processing unit 84 is, for example, control data for instructing execution of focus adjustment and control data for designating an optical zoom magnification. When the control data designating the optical zoom magnification is input from the control unit 70, the image processing unit 84 sends a drive signal to the zoom adjustment unit 96 so as to move the imaging lens 91 in accordance with the designated optical zoom magnification. Is output. Further, when control data instructing execution of focus adjustment is input from the control unit 70, the image processing unit 84 determines the in-focus state based on the captured image data output from the output circuit 95, and the focus adjustment unit 97 is driven. For example, the image processing unit 84 performs image processing such as edge detection and contrast measurement on the captured image data, and determines the in-focus state. Then, the image processing unit 84 moves the imaging lens 91 by the focus adjustment unit 97, and specifies the optimum position of the imaging lens 91 based on the change in the focus state of the captured image data accompanying the movement of the imaging lens 91. Further, the control unit 70 can output control data for instructing an offset for focus adjustment to the image processing unit 84. This control data includes data indicating an offset amount, that is, a correction amount. The image processing unit 84 can drive the focus adjustment unit 97 to execute focus adjustment, and then drive the focus adjustment unit 97 according to control data input from the control unit 70 to offset the focus position.

  The resolution conversion unit 86 performs processing for converting the resolution of the captured image data output from the image processing unit 84 to the resolution specified by the control unit 70. For example, the control unit 70 determines the resolution of the image data output from the document camera 50 to the projector 10 based on the control data input from the projector 10 via the USB interface unit 76, and converts the conversion to this resolution to the resolution conversion. The unit 86 is made to execute.

  The operation unit 74 detects an operation on the operation panel 60 (FIG. 1), and outputs data indicating the operation content to the control unit 70. The operation unit 74 is not limited to the operation panel 60 and may include other operation devices (not shown) operated by the user.

FIG. 3 is a plan view of a principal part showing a configuration example of the operation panel 60.
The operation panel 60 includes a power button 61 for performing a power on / off operation of the document camera 50. The operation panel 60 includes a menu button 63, an “Esc” button 64, and a direction instruction button 65. The operation panel 60 includes a zoom operation unit 66, a focus button 67, a still / photograph button 68, and a recording button 69.

  The menu button 63 is a button for displaying a menu for setting related to the function of the document camera 50. When the menu button 63 is operated, the operation unit 74 outputs control data indicating the operation of the menu button to the control unit 70. The control unit 70 generates image data for displaying a menu having a hierarchical structure according to control data input from the operation unit 74 and outputs the image data to the projector 10.

  The direction instruction button 65 is a button for instructing four directions of up, down, left, and right, and a determination button 65a is arranged at the center. The direction instruction button 65 is used for an operation of selecting an item in the menu displayed by the operation of the menu button 63. The determination button 65a is a button for instructing confirmation in response to selection by the operation of the direction instruction button 65. The [Esc] button 64 is a button for instructing the end of the function being executed. When the menu is displayed, the user is instructed to move to a hierarchy one level higher than the displayed hierarchy. The operation unit 74 detects the pressing operation of the direction instruction button 65 in the upper, lower, left, and right directions and the pressing operation of the determination button 65a, and outputs control data corresponding to the operation to the control unit 70. The control unit 70 changes the image data in accordance with the control data input from the operation unit 74. The user can perform various settings for the function of the document camera 50 by operating a hierarchical menu by operating the [Esc] button 64, the direction instruction button 65, and the enter button 65a.

  The direction instruction button 65 functions as a brightness adjustment button in a state where no menu is displayed. The brightness adjustment button is a button for instructing to change the brightness of the image data generated by the control unit 70 based on the captured image of the imaging unit 90. An upward operation of the direction instruction button 65 corresponds to an instruction to increase the brightness, and an downward operation of the direction instruction button 65 corresponds to an instruction to decrease the brightness. The control unit 70 adjusts the brightness of the image data output to the projector 10 when control data indicating the upward direction or the downward direction of the direction instruction button 65 is input from the operation unit 74 without displaying the menu. Specifically, the control unit 70 outputs control data to the illumination control unit 80 to change the luminance of the light source and / or controls to specify the brightness of the image data to the image processing unit 84. Process to output data.

  The zoom operation unit 66 is a button for instructing a change in zoom magnification when the imaging unit 90 images the subject T (FIG. 1). The zoom operation unit 66 includes a zoom UP button 66a for instructing an increase in the zoom magnification, and a zoom DOWN button 66b for instructing a decrease in the zoom magnification. The zoom UP button 66a and the zoom DOWN button 66b are pressed independently. it can. The focus button 67 is a button for instructing focus adjustment. When the operation unit 74 detects the operation of the zoom UP button 66 a, the zoom DOWN button 66 b, and the focus button 67, the operation unit 74 outputs control data corresponding to the operated button to the control unit 70.

  The still / photograph button 68 is a button for instructing a function to freeze the image output from the document camera 50 to the projector 10 and a function to save the captured image data captured by the imaging unit 90. The operation unit 74 according to the present embodiment repeatedly outputs control data indicating pressing of the still / shooting button 68 at a preset sampling cycle while the still / shooting button 68 is pressed. Based on the control data input from the operation unit 74, the control unit 70 depresses the static / photograph button 68 and releases it within a predetermined time (releases the press), and sets the static / photograph button 68 for a predetermined time. Distinguishes from operations that continue to be pressed. When the time for which the still / photograph button 68 is pressed is within a predetermined time, the control unit 70 executes a function of causing the document camera 50 to freeze the image output to the projector 10. In addition, when the time during which the still / photograph button 68 is pressed exceeds a predetermined time, the control unit 70 performs processing for saving the captured image data captured by the imaging unit 90. The recording button 69 is a button for instructing a process of saving captured image data of the imaging unit 90 as moving image data.

The control unit 70 includes a zoom control unit 70a, a focus control unit 70b, a correction amount deriving unit 70c, and a mode switching unit 70d. Each of these units is realized by cooperation of software and hardware by the CPU of the control unit 70 executing the above-described program.
The zoom control unit 70a changes the optical zoom magnification and / or enlarges / reduces the captured image data based on control data indicating the operation of the zoom UP button 66a and the zoom DOWN button 66b input from the operation unit 74. Perform the change process. The document camera 50 has an optical zoom function for enlarging / reducing the captured image by operating the zoom adjustment unit 96 and a digital zoom function for performing image processing for enlarging / reducing the captured image data output from the output circuit 95. The image processing unit 84 executes image processing related to the digital zoom function. The optical zoom function and the digital zoom function can be turned on / off independently by a menu operation using the menu button 63, for example. In accordance with this setting, the zoom control unit 70a changes the optical zoom magnification or the digital zoom magnification according to the operation of the zoom UP button 66a or the zoom DOWN button 66b. When the optical zoom magnification is changed, the zoom control unit 70 a outputs control data for designating an adjustment value of the optical zoom magnification to the image processing unit 84. The image processing unit 84 drives the zoom adjustment unit 96 according to the adjustment value of the optical zoom magnification specified by the control data output from the zoom control unit 70a. In addition, when the magnification of the digital zoom is changed, the zoom control unit 70a outputs control data indicating the changed digital zoom magnification to the image processing unit 84, and the image processing unit 84 captures captured image data according to the changed zoom magnification. Image processing for enlarging or reducing the image is performed.

The focus control unit 70b outputs control data that instructs the image processing unit 84 to execute focus adjustment, and causes the focus adjustment to be performed.
The focus control unit 70b executes focus adjustment when control data instructing execution of focus adjustment is input from the operation unit 74 to the control unit 70, that is, when the focus button 67 is operated. In addition, the focus control unit 70b starts imaging of the subject T when the power of the document camera 50 is turned on, or the zoom adjustment unit 96 changes the optical zoom magnification according to the operation of the zoom operation unit 66. It may be executed. In addition, the focus control unit 70b may perform focus adjustment when control data including a command for instructing focus adjustment is input from the projector 10.

With this configuration, the document camera 50 images the subject T by the imaging unit 90, generates display image data with a resolution suitable for the projector 10 based on the captured image data, and outputs the image data to the projector 10. The projector 10 projects an image of the subject T placed on the base 52 onto the screen SC.
When the user operates the focus button 67, the focus adjustment for the subject T is performed. For example, even if the subject T is a thick object or book, a high-quality image in focus can be projected by the projector 10. In addition, since the zoom magnification at the time of imaging of the subject T can be adjusted by the user operating the zoom UP button 66a and the zoom DOWN button 66b, the image of the subject T can be projected by the projector 10 at an arbitrary magnification.

  Further, when the focus adjustment is offset, the focus control unit 70 b outputs control data instructing the focus adjustment offset to the image processing unit 84. This control data includes data indicating the offset amount.

The image processing unit 84 performs focus adjustment by driving the focus adjustment unit 97 so that the in-focus state in the imaging unit 90 is good. After the focus adjustment, the captured image data output from the imaging unit 90 is in a so-called focused state. When the focus adjustment is offset, the imaging lens 91 is moved from the position after the focus adjustment and the in-focus state is lowered. However, depending on the type of the subject T, an improvement in the image quality of the captured image data can be expected.
For example, when the subject T has a display screen such as a liquid crystal display panel or an organic EL panel and the display screen is imaged by the imaging unit 90, it is known that so-called moire occurs in the captured image data. This phenomenon is caused by the regular arrangement of the pixels constituting the display screen such as a liquid crystal display panel or an organic EL panel and the pixels of the image sensor 92 that receives light from the display screen. It is understood that moire (interference fringes) occurs due to a relative positional shift between the pixels of the image sensor and the pixels of the image sensor 92. The document camera 50 makes it possible to suppress or prevent moire by offsetting the focus adjustment state when the subject T is a display screen.

  The focus control unit 70b causes the correction amount deriving unit 70c to derive the offset amount for offsetting the focus adjustment, that is, the correction amount, when the execution condition of the operation for suppressing moire is satisfied. Then, the focus control unit 70b outputs control data for offsetting the focus adjustment to the image processing unit 84. Further, if the execution condition of the operation for suppressing the moire is satisfied before the image processing unit 84 executes the focus adjustment, the control data for offsetting the focus adjustment may be output together with the control data for instructing the focus adjustment. Good.

The correction amount deriving unit 70c derives a correction amount for focus adjustment using the correction amount information 72a stored in the storage unit 72. More specifically, the correction amount deriving unit 70c performs processing for obtaining a correction amount corresponding to the adjustment value of the optical zoom magnification in the imaging unit 90. Specific examples of the process for deriving the correction amount include the following two methods.
(1) The correction amount is acquired with reference to a table that associates the adjustment value of the optical zoom magnification with the correction amount of the focus adjustment.
(2) An arithmetic process is performed based on the adjustment value of the optical zoom magnification, and a correction amount for focus adjustment is calculated.

In the present embodiment, the example (1) will be described. In this example, the storage unit 72 stored in the storage unit 72 stores correction amount information 72a in a table format in which correction amounts are set.
FIG. 4 is a diagram schematically illustrating a configuration example of the correction amount information 72a.
As shown in FIG. 4, the document camera 50 of the present embodiment can adjust the optical zoom magnification in 120 steps by the zoom adjustment unit 96, the adjustment value is 1 to 120, and the adjustment value 0 is the minimum optical zoom magnification. The adjustment value 120 corresponds to a state in which the zoom magnification is maximum. In the correction amount information 72a, a correction amount for focus adjustment is set in association with the adjustment values 1 to 120. The correction amount is set in 9 stages of 4 to 12, and when the optical zoom magnification is maximum (adjustment value 120), the correction amount is 4 (minimum value), and when the optical zoom magnification is minimum (adjustment value 0). The correction amount is 12 (maximum value).

FIG. 5 is a chart showing the relationship between the adjustment value of the optical zoom magnification and the correction amount acquired by the correction amount deriving unit 70c. The horizontal axis indicates the adjustment value of the optical zoom magnification, and the vertical axis indicates the correction amount of the focus adjustment.
As shown in FIG. 5, the correction amount information 72a is set so that the correction amount for focus adjustment decreases as the optical zoom magnification increases. Accordingly, the larger the adjustment value of the optical zoom magnification of the zoom adjustment unit 96, the smaller the correction amount derived by the correction amount deriving unit 70c.

  In the example of FIG. 4, the focus adjustment correction amount is associated with all the adjustment values of the optical zoom magnification that can be set in the zoom adjustment unit 96. The present invention is not limited to this. For example, a part of the adjustment value of the optical zoom magnification may be a representative value, and a focus adjustment correction amount corresponding to the representative value may be associated with the representative value. In this case, the correction amount deriving unit 70c can calculate the correction amount for all the adjustment values of the optical zoom magnification by performing an interpolation operation on the correction amount value corresponding to the representative value of the optical zoom magnification.

  In the case of (2) above, the correction amount information 72a is an arithmetic expression, function or program for calculating the correction amount from the optical zoom magnification. In this case, the correction amount information 72a corresponds to information for obtaining the correction amount. In this case, the correction amount deriving unit 70c can calculate the correction amount by inputting the adjustment value of the optical zoom magnification into the correction amount information 72a. Even when the method (2) is used, the correction amount information 72a is configured such that the correction amount for focus adjustment decreases as the optical zoom magnification increases. Further, the correction amount information 72a may be information including the correction amount itself.

  Specifically, the correction amount derived by the correction amount deriving unit 70c is an amount by which the position of the imaging lens 91 is offset, for example, the number of operation steps of the stepping motor of the focus adjustment unit 97 that moves the imaging lens 91. . When suppressing moire, the focus adjustment unit 97 moves the position of the imaging lens 91 in a suitable in-focus state by an amount corresponding to the correction amount (for example, the number of operation steps). The moving direction in this case may be, for example, a direction in which the focus (focus) of the imaging lens 91 is moved to the subject T side or a direction in which the imaging lens 91 is moved toward the imaging element 92 side. In addition, the correction amount may include an attribute that designates the moving direction of the imaging lens 91 or the moving direction of the focus. Specifically, the correction amount may have a positive or negative sign.

  The execution condition for executing the operation of suppressing the moire by the focus control unit 70b is, for example, that the operation of suppressing the moire is set to “on” in the setting menu of the document camera 50 by operating the menu button 63 and the direction instruction button 65. Is the case.

  The document camera 50 according to the present embodiment includes a “display mode” (first operation mode) suitable for imaging a display screen included in a display device (for example, a terminal device such as a smartphone or a tablet) as the subject T. A plurality of operation modes can be switched and executed. In the present embodiment, the mode switching unit 70d switches between two operation modes: a “display mode” and a “normal operation mode” (second operation mode) that does not perform focus adjustment offset. For example, when the operation mode is designated in the setting menu of the document camera 50 by the operation of the menu button 63 and the direction instruction button 65, the mode switching unit 70d performs switching to the designated operation mode. When the mode switching unit 70d switches the operation mode of the document camera 50 to the focus adjustment mode, the focus control unit 70b executes a focus adjustment offset to suppress moire.

FIG. 6 is a flowchart showing the operation of the document camera 50, (A) shows the operation of the control unit 70, and (B) shows the operation of the image processing unit 84.
Based on the control data input from the operation unit 74, the control unit 70 determines whether or not the focus button 67 of the operation panel 60 has been operated (step S11). When it is determined that the focus button 67 is not operated (step S11; No), the control unit 70 determines whether or not switching of the operation mode is instructed by the menu operation (step S12). If it is determined that there is no instruction to switch the operation mode (step S12; No), the control unit 70 returns to step S11. The control unit 70 executes the operation of step S11 every predetermined time, and waits for the operation of the focus button 67 and the operation for instructing the switching of the operation mode.

When the focus button 67 is operated (step S11; Yes) and when switching of the operation mode is instructed (step S12; Yes), the control unit 70 starts focus adjustment (step S13). In step S <b> 13, the control unit 70 outputs control data instructing focus adjustment to the image processing unit 84. The image processing unit 84 shifts to the focus adjustment mode in accordance with the control data input from the control unit 70 (step S21).
The image processing unit 84 executes, for example, switching between two operation modes. That is, the normal operation mode in which the captured image data output from the output circuit 95 is output to the control unit 70 and the focus adjustment unit 97 are driven, and the in-focus state is determined based on the captured image data output from the output circuit 95. The focus adjustment mode for performing the focus adjustment is executed. The normal operation mode includes a display mode that is a first operation mode and a normal operation mode that is a second operation mode. In step S21, the image processing unit 84 shifts from the normal operation mode to the focus adjustment mode.

The control unit 70 determines whether or not the current operation mode of the control unit 70 is the display mode (step S14). When the operation mode is the display mode (step S14; Yes), the focus adjustment with an offset is executed. That is, the correction amount deriving unit 70c acquires the zoom magnification adjustment value of the zoom control unit 70a (step S15), and derives the focus adjustment correction amount based on the correction amount information 72a (step S16). Then, the focus control unit 70b outputs control data including the focus adjustment instruction and the correction amount derived by the correction amount deriving unit 70c to the image processing unit 84 to instruct focus adjustment (step S17).
If the current operation mode of the control unit 70 is not the display mode (step S14; No), the focus control unit 70b outputs control data instructing focus adjustment to the image processing unit 84 (step S18).

  The image processing unit 84 receives control data for instructing focus adjustment from the control unit 70 (step S22), and determines whether or not the control data designates an offset (step S23). When focus adjustment without specifying an offset is instructed (step S23; No), the image processing unit 84 performs focus adjustment (step S24). When the focus adjustment for specifying the offset is instructed (step S23; Yes), the image processing unit 84 performs the focus adjustment with the correction amount (step S25).

As described above, the document camera 50 according to the embodiment to which the present invention is applied includes the zoom adjustment unit 96 that changes the optical zoom magnification and the imaging unit 90 that includes the focus adjustment unit 97 that performs focus adjustment. The document camera 50 controls the focus adjustment unit 97 based on the correction amount deriving unit 70c for deriving the focus adjustment correction amount corresponding to the optical zoom magnification of the zoom adjustment unit 96 and the correction amount derived by the correction amount deriving unit 70c. And an image processing unit 84 that performs focus adjustment.
According to the configuration of the document camera 50 and the imaging method executed by the document camera 50, since the focus state is adjusted in accordance with the optical zoom magnification, moire can be reduced without significantly reducing the image quality of the captured image. Can be suppressed.

  The document camera 50 also includes a storage unit 72 that stores correction amount information 72 a that defines the relationship between the optical zoom magnification of the zoom adjustment unit 96 and the correction amount. The correction amount deriving unit 70 c derives a correction amount for focus adjustment corresponding to the optical zoom magnification of the zoom adjustment unit 96 based on the correction amount information 72 a stored in the storage unit 72. As a result, information that defines the relationship between the optical zoom magnification and the correction amount is stored, and the correction amount for focus adjustment is derived using this information, so that the focus state can be quickly and appropriately adjusted.

  In the document camera 50, the storage unit 72 stores correction amount information 72 a in association with the optical zoom magnification of the zoom adjustment unit 96. The correction amount information 72a is information for obtaining the correction amount or information including the correction amount, and here, an example configured as information in a table format is shown. When the correction amount information 72a including information for obtaining the correction amount is stored in the storage unit 72, the control unit 70 quickly derives an appropriate focus adjustment correction amount corresponding to the optical zoom magnification, and the focus state Can be adjusted.

  In the document camera 50, the storage unit 72 corresponds to a second optical zoom magnification that is higher than the first optical zoom magnification compared to the correction amount corresponding to the first optical zoom magnification of the zoom adjustment unit 96. The correction amount information 72a that is a correction amount with a small correction amount is stored. That is, the correction amount information 72a defines the relationship between the optical zoom magnification and the correction amount so that the larger the optical zoom magnification is, the smaller the correction amount is. Accordingly, it is possible to appropriately adjust the focus state in accordance with the optical zoom magnification, and to suppress deterioration in the image quality of the captured image.

  Further, the document camera 50 includes a mode switching unit 70d that switches between a display mode (first operation mode) and a normal operation mode (second operation mode). The image processing unit 84 performs focus adjustment based on the correction amount derived by the correction amount deriving unit 70c in the display mode, and performs focus adjustment without using the correction amount derived by the correction amount deriving unit 70c in the normal operation mode. Is executed. Thereby, by switching the operation mode, it is possible to select a state in which the focus adjustment for suppressing moire is executed and a state in which the adjustment is not executed. For example, when capturing a display that displays an image, moiré of the captured image can be suppressed by switching to the first operation mode. Also, for example, by switching to the second operation mode when imaging other subjects, a high-quality captured image that is in focus can be obtained.

In the document camera 50, the image processing unit 84 is based on the correction amount derived by the correction amount deriving unit 70c when the operation mode of the document camera 50 is switched from the normal operation mode to the display mode by the mode switching unit 70d. Execute focus adjustment.
Thereby, since the focus state is adjusted so as to suppress moire when the operation mode is switched, operability can be improved.
Further, by performing the determination shown in step S12 of FIG. 6, the control unit 70 can cause the image processing unit 84 to perform focus adjustment when the operation mode is switched from the display mode to the normal operation mode. . Thereby, when it is no longer necessary to offset the focus adjustment, the focus adjustment to a suitable in-focus state can be performed promptly.

  The display mode executed by the document camera 50 is an operation mode suitable for imaging a display screen provided in a display device (for example, a terminal device such as a smartphone or a tablet). The normal operation mode is an operation mode different from the display mode. For this reason, it is possible to perform the focus adjustment based on the correction amount in a display mode suitable for a situation where moiré is likely to occur, thereby suppressing the occurrence of moiré. When there is little concern about the occurrence of moiré, for example, the normal operation mode can be executed to obtain a high-quality captured image.

  Further, the document camera 50 includes an operation unit 74 that receives an operation, and the image processing unit 84 performs focus adjustment based on an operation on the operation unit 74. For example, when the operation unit 74 detects an operation of the focus button 67, the image processing unit 84 can perform focus adjustment under the control of the control unit 70. Thereby, the adjustment of the focus which suppresses a moire can be performed as needed, and operability can be improved.

The above-described embodiments are merely examples of specific modes to which the present invention is applied, and do not limit the present invention. For example, the zoom adjustment unit 96 and the focus adjustment unit 97 are not limited to a configuration that automatically operates under the control of the image processing unit 84. For example, the control unit 70 may be configured to perform zoom adjustment by controlling the zoom adjustment unit 96 without using the image processing unit 84. Alternatively, the control unit 70 may control the focus adjustment unit 97 without using the image processing unit 84 to perform focus adjustment. In this case, the zoom adjustment unit 96 may be connected to the control unit 70, and the focus adjustment unit 97 may be connected to the control unit 70.
The zoom adjustment unit 96 may be configured such that the user manually adjusts the optical zoom magnification, and it is sufficient that the control unit 70 can acquire the current value of the zoom magnification. Alternatively, the focus adjustment unit 97 may be configured to perform focus adjustment by operating the operation panel 60 by the user. In this case, if the control unit 70 operates the focus adjustment unit 97 according to the correction amount derived by the correction amount deriving unit 70c after the adjustment by the user's operation, the present invention can be applied.
Further, the focus control unit 70 b included in the control unit 70 may instruct the image processing unit 84 to perform focus adjustment in accordance with control data input from the projector 10 via the USB cable 59. The mode switching unit 70d may switch the operation mode according to control data input from the projector 10. In this case, for example, by operating the remote control 38 or the operation panel of the projector 10, the projector 10 can send a control command for the document camera 50 to adjust the focus of the document camera 50 and switch the operation mode.

  Further, the projector 10 and the document camera 50 are not limited to a wired connection using the USB cable 59, and may be connected via a communication interface other than USB such as HDMI (High-Definition Multimedia Interface) (registered trademark). . In the configuration in which the projector 10 and the document camera 50 are connected by an interface capable of transmitting and receiving control data such as USB connection and HDMI connection, the control data is transmitted from the projector 10 to the document camera 50 as described above, and the document camera is transmitted. 50 can be controlled. Thereby, since the operation of the document camera 50 can be controlled by the user performing an operation on the projector 10, there is an advantage that usability is improved. Further, the projector 10 and the document camera 50 are not limited to the configuration in which they are connected by wire, and may be connected by a wireless communication line such as a wireless LAN (including WiFi (registered trademark)), Bluetooth (registered trademark), or the like.

  Further, the imaging apparatus of the present invention is not limited to the document camera 50 connected to the projector 10 as described above. Any device may be used as long as it has a configuration for adjusting the focus and a configuration for adjusting the optical zoom magnification and performs imaging. More specifically, any device may be used as long as it includes an imaging device having regularly arranged pixels and performs imaging using light received by the imaging device. Therefore, the present invention can be applied to electronic devices such as digital still cameras, digital video cameras, mobile phones equipped with these cameras, smartphones, tablet computers, and notebook computers. The present invention can also be applied to an imaging system including a digital still camera and a digital video camera, and a computer connected to these cameras and acquiring captured image data. In this case, a configuration unit including a digital still camera and a digital video camera and a function of controlling the camera focus adjustment and zoom magnification adjustment in a computer corresponds to an imaging apparatus.

In the projector 10, the light modulation device that modulates the light emitted from the light source is not limited to the configuration using the transmissive liquid crystal panel. For example, the configuration using the reflective liquid crystal panel or the configuration using the digital mirror device (DMD). It may be.
In addition, the device to which the document camera 50 is connected is not limited to the projector 10. For example, the document camera 50 may be connected to a display device that displays an image based on captured image data captured by the document camera 50. . In this case, the document camera 50 may be connected to a monitor device or a television receiver that displays an image on a liquid crystal display panel, a PDP (plasma display panel), an organic EL display panel, or the like. Further, the document camera 50 may be connected to a recording device that records image data output from the document camera 50. In this case, as an interface for connecting the document camera 50 to a device to which the document camera 50 is connected, a USB interface, HDMI, other wired communication interface, or a wireless communication interface can be used as described above.

  Further, the functional blocks shown in FIG. 2 indicate functional configurations of the projector 10 and the document camera 50, and do not limit a specific mounting form. In other words, it is not necessary to implement hardware corresponding to the functional blocks in the figure, and it is of course possible to adopt a configuration in which the functions of a plurality of functional units are realized by one processor executing a program. In addition, in the above embodiment, a part of the function realized by software may be realized by hardware, or a part of the function realized by hardware may be realized by software. In addition, specific detailed configurations of other parts of the apparatus constituting the projection system 100 can be arbitrarily changed without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Projector, 20 ... Control part, 22 ... Memory | storage part, 24 ... Operation part, 26 ... USB interface part, 28 ... Input interface part, 30 ... Input source switching part, 32 ... Image processing part, 34 ... Projection part, 36 ... Bus 38 ... Remote control 50 ... Document camera (imaging device) 54 ... Placing surface 59 ... USB cable 60 ... Operation panel 67 ... Focus button 70 ... Control unit 70a ... Zoom control unit 70b ... Focus control unit, 70c ... correction amount deriving unit, 70d ... mode switching unit, 72 ... storage unit, 72a ... correction amount information, 74 ... operation unit, 76 ... USB interface unit, 78 ... illumination unit, 80 ... illumination control unit, 84: Image processing unit (focus control unit), 86: Resolution conversion unit, 90 ... Imaging unit, 91 ... Imaging lens, 92 ... Imaging element, 95 ... Output circuit, 96 ... Arm adjustment unit, 97 ... focus adjusting section, 100 ... projection system 201 ... personal computer, 202 ... VTR, 203 ... DVD player, AX ... optical axis, SC ... screen, T ... subject.

Claims (9)

A zoom adjustment unit for changing the optical zoom magnification, and an imaging unit having a focus adjustment unit for performing focus adjustment;
A correction amount deriving unit for deriving a correction amount of focus adjustment corresponding to the optical zoom magnification of the zoom adjustment unit;
A focus control unit for controlling the focus adjustment unit based on a correction amount derived by the correction amount deriving unit and executing focus adjustment;
An imaging apparatus comprising: A storage unit that stores correction amount information that defines a relationship between the optical zoom magnification of the zoom adjustment unit and the correction amount;
The correction amount deriving unit derives a correction amount for focus adjustment corresponding to the optical zoom magnification of the zoom adjustment unit based on the correction amount information stored in the storage unit;
The imaging apparatus according to claim 1. The storage unit stores information for obtaining the correction amount or the correction amount information in a table format including the correction amount in association with the optical zoom magnification of the zoom adjustment unit;
The imaging apparatus according to claim 2. The storage unit has a correction amount in which the correction amount corresponding to the second optical zoom magnification higher than the first optical zoom magnification is smaller than the correction amount corresponding to the first optical zoom magnification of the zoom adjustment unit. Storing the correction amount information to be
The imaging apparatus according to claim 2 or 3, wherein A mode switching unit that switches between and executes the first operation mode and the second operation mode;
The focus control unit performs focus adjustment based on the correction amount derived by the correction amount deriving unit in the first operation mode, and determines the correction amount derived by the correction amount deriving unit in the second operation mode. To perform focus adjustment without using it,
The imaging device according to claim 1, wherein: The focus control unit is based on the correction amount derived by the correction amount deriving unit when the operation mode of the imaging apparatus is switched from the second operation mode to the first operation mode by the mode switching unit. Performing focus adjustments,
The imaging apparatus according to claim 5. The first operation mode is a mode suitable for imaging a display screen, and the second operation mode is an operation mode different from the first operation mode;
The imaging device according to claim 5 or 6. It has an operation unit that accepts operations,
The focus control unit performs focus adjustment based on an operation on the operation unit;
The imaging apparatus according to claim 1, wherein: Using an imaging unit that can change the optical zoom magnification and adjust the focus,
Deriving the amount of focus adjustment correction corresponding to the optical zoom magnification,
Perform focus adjustment based on the derived correction amount,
Taking an image after focus adjustment,
An imaging method characterized by the above.

Images