JP2016143951A - Image processing apparatus, imaging device, image processing method and image processing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing apparatus which can detect the brightness of a subject well, even if the aperture of a lens at the imaging time cannot be acquired from an interchangeable lens, and performs highly accurate white balance correction according to the brightness of the subject, and to provide an imaging device, an image processing method and an image processing program.SOLUTION: The brightness of a subject is detected based on an image captured by an imaging device, the aperture at the time of imaging and the shutter speed, and white balance of the captured image is corrected based on the brightness of the subject thus detected. When the aperture of a lens at the time of imaging cannot be acquired from an interchangeable lens, the aperture at the time of imaging is estimated by an aperture estimation unit. The aperture estimation unit estimates the aperture at the time of imaging based on the shutter speeds when imaging a flash emission image and a flash non-emission image, the subject distance, the guide number of flash light when imaging the flash emission image, and the amount of reached flash light.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image processing apparatus, an imaging apparatus, an image processing method, and an image processing program, and more particularly to a technique applied to white balance correction.

  An interchangeable lens digital camera to which an interchangeable lens is attached or detached can be roughly divided into two types of interchangeable lenses.

  One interchangeable lens is an interchangeable lens manufactured according to the communication standard of the camera body and capable of communicating with the camera body. When this type of interchangeable lens is mounted on the camera body, the camera body communicates with the mounted interchangeable lens, and the lens information of the interchangeable lens (for example, the aperture value (F value of the aperture in the interchangeable lens)) ), The lens position of the focus lens, the focal length of the interchangeable lens, etc.) can be completely acquired.

  The other interchangeable lens is an interchangeable lens that is not manufactured in accordance with the communication standard of the camera body and cannot perform complete communication with the camera body, and a third-party interchangeable lens or an old lens is not used. Applicable. The communication protocol between the interchangeable lens and the camera body is different, and some lens information can be acquired by the camera body. However, in this example, the lens that cannot acquire at least the F value is the other in this example. Applicable to interchangeable lenses.

  When the latter interchangeable lens is attached to the camera body, the camera body has various functions such as automatic exposure (AE) control, autofocus (AF) control, auto white balance (AWB) control, etc. Automatic control cannot be implemented completely.

  For example, in the case of AWB control (automatic white balance correction), the light source is estimated from the brightness of the subject and AWB control is often performed according to the estimated light source, but the lens information of the interchangeable lens is not known. In this case, since the aperture value of the lens is unknown, the brightness of the subject cannot be obtained.

  Patent Document 1 discloses a luminance signal of an imaged image, a diaphragm open state (lens open aperture value), an electronic shutter control state (shutter speed), and an AGC (Automatic Gain Control) amplifier gain state (image capture). A white balance correction device that detects the brightness of a subject based on sensitivity, estimates a light source that illuminates the subject based on the detected brightness of the subject, and performs white balance correction according to the estimated light source. Yes.

  Patent Document 2 describes a digital camera system that performs white balance correction in accordance with an aperture value at the time of imaging with a detachable lens unit.

JP 2008-301279 A JP 2006-074076 A

  There is no description in Patent Document 1 that the lens is an interchangeable lens, and the white balance correction device described in Patent Document 1 can acquire the aperture value of the lens from the lens and detects the brightness of the subject. It is assumed that it can be done.

  However, as described above, if the lens described in Patent Document 1 is a third-party interchangeable lens or an old lens, and the aperture value of the lens cannot be obtained from the interchangeable lens, the brightness of the subject is obtained. I can't.

  If the aperture value of the interchangeable lens is unknown, light source estimation may be performed with the aperture value fixed to the representative value, but if the aperture value is different from the representative value, white balance correction cannot be performed properly. There is a problem that a color failure is caused and the color of the image after white balance correction is deteriorated. Information on the brightness of the subject is often used to distinguish between light sources that are outdoors during the day (sunlight) and other light sources (artificial light sources). Thus, when the white balance correction corresponding to the artificial light source is performed, the color feria tends to increase.

  On the other hand, Patent Document 2 describes a digital camera system that performs white balance correction according to an aperture value at the time of imaging of a detachable lens unit. The reason for acquiring an aperture value at the time of imaging of a lens unit is described below. This is because the spectral characteristic of the lens unit changes according to the aperture value and white balance correction is performed according to the spectral characteristic, and the F value of the lens unit is not acquired in order to detect the brightness of the subject. Further, there is no description regarding a technique for obtaining the aperture value when the aperture value of the interchangeable lens is unknown.

  The present invention has been made in view of such circumstances, and even if the interchangeable lens cannot acquire the aperture value of the lens at the time of imaging from the interchangeable lens because of a third-party interchangeable lens, old lens, etc. It is possible to provide an image processing apparatus, an imaging apparatus, an image processing method, and an image processing program that can detect the brightness of the image and perform white balance correction with high accuracy according to the brightness of the subject. And

  In order to achieve the above object, an image processing apparatus according to an aspect of the present invention is an aperture value at the time of imaging of an image of a subject imaged by an interchangeable lens imaging device equipped with an interchangeable lens. An aperture value acquisition unit that acquires an aperture value from a lens, an aperture value estimation unit that estimates an aperture value when the aperture value acquisition unit cannot acquire an aperture value at the time of imaging from an interchangeable lens, and an image captured by an imaging device A brightness detection unit that detects the brightness of the subject based on the aperture value acquired by the aperture value acquisition unit or the aperture value estimated by the aperture value estimation unit, and the shutter speed at the time of imaging, and is detected by the brightness detection unit A white balance correction unit that corrects the white balance of the image captured based on the brightness of the subject, and the aperture value estimation unit is an image captured by the imaging device, An image acquisition unit for acquiring a flash emission image captured by emitting the guide number flash light and a flash non-emission image captured without emitting the flash light, and a flash emission image and a flash non-emission image, respectively. An imaging condition acquisition unit that acquires the shutter speed, subject distance, and guide number at the time of imaging, and flash light arrival that calculates the flash light arrival amount from the difference between the flash emission image and the flash non-emission image acquired by the image acquisition unit An aperture value at the time of image capture based on the guide number and subject distance acquired by the imaging condition acquisition unit and the flash light arrival amount calculated by the flash light arrival amount calculation unit. To do.

  According to one aspect of the present invention, the brightness of a subject is detected based on the image captured by the imaging device, the aperture value at the time of capturing, and the shutter speed, and the image captured based on the detected brightness of the subject. Correct the white balance. This makes it possible to perform white balance correction with high accuracy according to the brightness of the subject.

  In addition, if the interchangeable lens cannot be obtained from the interchangeable lens due to a third-party interchangeable lens, old lens, etc., the aperture value at the time of imaging is estimated by the aperture value estimation unit. To do. The aperture value estimator is based on the shutter speed, subject distance, flash light guide number when the flash emission image is captured, and the amount of flash light reached based on the shutter speed when the flash emission image and flash non-emission image are captured. Estimate the value.

  In the image processing device according to another aspect of the present invention, the white balance correction unit includes a determination unit that determines whether the subject is an outdoor subject during the day based on the brightness of the subject detected by the brightness detection unit, It is preferable to change the correction content of the white balance correction of the image according to the determination result by the determination unit. Based on the detected brightness of the subject, it is possible to determine whether the light source that illuminates the subject is a daylight outdoor light source (sunlight) or another light source (artificial light source). As a result, it is possible to prevent a malfunction (occurrence of color feria) in which white balance correction corresponding to an artificial light source is performed on an image captured outdoors in the daytime, and to perform highly accurate white balance correction. Can do.

In the image processing apparatus according to still another aspect of the present invention, the aperture value estimation unit includes a sensitivity acquisition unit that acquires sensitivity at which the amount of flash light reaches the appropriate exposure amount, and sets a sensitivity coefficient corresponding to the acquired sensitivity. K, where the guide number and subject distance acquired by the imaging condition acquisition unit are GN and D, respectively, the aperture value F to be estimated is given by
F = GN × K ÷ D
Calculated by

  The flash light arrival amount can be calculated from the difference between the flash emission image and the flash non-light emission image. However, when the calculated flash light arrival amount does not reach the appropriate exposure amount or exceeds the appropriate exposure amount, By adjusting the sensitivity, proper exposure can be achieved. Therefore, the sensitivity coefficient K corresponding to the acquired sensitivity can be obtained by acquiring the sensitivity at which the flash light arrival amount is the appropriate exposure amount.

  On the other hand, the guide number GN is an index indicating the light emission amount at the time of flash imaging, and when the sensitivity adjustment is not performed (when the sensitivity coefficient K is 1), the guide distance GN is divided by the subject distance D. It is possible to calculate an aperture value F for imaging the subject with appropriate exposure. When the sensitivity is adjusted so that the exposure is appropriate (when the sensitivity coefficient K is not 1), the aperture value F is calculated by further multiplying the aperture value F calculated as described above by the sensitivity coefficient K. Can do. The aperture value F calculated in this way can be estimated as the aperture value of the lens when the flash emission image and the flash non-emission image are captured.

  An imaging apparatus according to still another aspect of the present invention includes a lens mounting unit to which an interchangeable lens can be attached, an imaging unit that captures an image of a subject via an interchangeable lens mounted to the lens mounting unit, and a lens mounting unit. An aperture value acquisition unit that acquires an aperture value at the time of imaging from a mounted interchangeable lens, and an aperture at the time of imaging when the aperture value acquisition unit cannot acquire an aperture value at the time of imaging from an interchangeable lens mounted on the lens mounting unit The brightness of the subject based on the aperture value estimation unit that estimates the value, the image captured by the imaging unit, the aperture value acquired by the aperture value acquisition unit or the aperture value estimated by the aperture value estimation unit, and the shutter speed at the time of imaging A brightness detection unit that detects the brightness, and a white balance correction unit that corrects the white balance of the image captured by the imaging unit based on the brightness of the subject detected by the brightness detection unit. The aperture value estimation unit is an image captured by the imaging unit, which is a flash emission image captured by emitting flash light with a predetermined guide number, and a flash non-emission image captured without emitting flash light. An image acquisition unit for acquiring images, an imaging condition acquisition unit for acquiring a shutter speed, a subject distance, and a guide number when capturing a flash emission image and a flash non-emission image, and a flash emission image acquired by the image acquisition unit A flash light arrival amount calculation unit that calculates the flash light arrival amount from the difference between the image and the non-flash image, and the guide number and subject distance acquired by the imaging condition acquisition unit and the flash light arrival amount calculation unit The aperture value at the time of capturing an image is estimated based on the amount of flash light that has been reached.

  An imaging apparatus according to still another aspect of the present invention includes an interchangeable lens mounted on the lens mounting unit and a communication unit capable of communicating via the lens mounting unit, and the aperture value acquisition unit is configured such that the communication unit is an interchangeable lens. When communication is possible, it is preferable to obtain the aperture value of the interchangeable lens via the communication unit.

  In the imaging device according to still another aspect of the present invention, the white balance correction unit includes a determination unit that determines whether the subject is an outdoor subject during the day based on the brightness of the subject detected by the brightness detection unit, It is preferable to change the correction content of the white balance correction of the image according to the determination result by the determination unit. Since it is determined whether the subject is an outdoor subject during the day and the correction content of the white balance correction of the image is changed according to the determination result, it is possible to perform highly accurate white balance correction that does not cause color failure.

In the imaging apparatus according to still another aspect of the present invention, the aperture value estimation unit includes a sensitivity acquisition unit that acquires sensitivity at which the amount of flash light reaches the appropriate exposure amount, and sets a sensitivity coefficient corresponding to the acquired sensitivity to K. When the guide number and subject distance acquired by the imaging condition acquisition unit are GN and D, respectively, the estimated aperture value F is expressed by the following equation:
F = GN × K ÷ D
Calculated by

  An imaging apparatus according to still another aspect of the present invention includes a lens position acquisition unit that acquires a lens position of a focus lens of an interchangeable lens when focused on a subject, and the imaging condition acquisition unit is acquired by the lens position acquisition unit It is preferable to acquire the subject distance based on the lens position of the focus lens. For example, each lens position when the focus lens of the interchangeable lens is moved to the nearest end and infinity manually or automatically when the interchangeable lens is mounted is acquired, and each acquired lens position and the subject are focused. The subject distance is acquired from the relationship with the lens position of the focus lens.

  In the imaging apparatus according to still another aspect of the present invention, based on the focal length information of the interchangeable lens and the size of the predetermined subject in the captured image when focused on the predetermined subject having a known size. Preferably, a subject distance estimation unit that estimates a distance to a predetermined subject is provided, and the imaging condition acquisition unit acquires the subject distance estimated by the subject distance estimation unit from the subject distance estimation unit. For example, a human face is suitable as the predetermined subject of known size.

  An imaging apparatus according to still another aspect of the present invention includes a wireless communication unit that wirelessly communicates with a mobile terminal carried by a subject, and the imaging condition acquisition unit is configured to control the intensity of radio waves received from the mobile terminal by the wireless communication unit. It is preferable to acquire the subject distance based on this.

  An imaging apparatus according to still another aspect of the present invention includes a GPS information acquisition unit that acquires GPS information, and the imaging condition acquisition unit indicates GPS information indicating the position of the subject acquired by the GPS information acquisition unit and the imaging position. It is preferable to acquire the subject distance based on the GPS information.

  An imaging apparatus according to still another aspect of the present invention includes a wireless communication unit that receives position information from a position information transmission unit that transmits position information indicating the position of a fixed subject, and the imaging condition acquisition unit includes a wireless communication unit It is preferable to acquire the subject distance based on the positional information indicating the position of the fixed subject acquired by and the positional information indicating the imaging position.

  An image processing method according to still another aspect of the present invention is an aperture value at the time of capturing an image of a subject imaged by an image-capable imaging device equipped with an interchangeable lens, and the aperture value is obtained from the interchangeable lens. The step of estimating the aperture value when the aperture value at the time of imaging cannot be acquired from the interchangeable lens by the step of acquiring the aperture value, the image captured by the imaging device, the acquired aperture value or the estimated aperture value And detecting the brightness of the subject based on the shutter speed at the time of imaging, and correcting the white balance of the captured image based on the detected brightness of the subject, and estimating the aperture value The step of performing is an image captured by an imaging device, and a flash emission image captured by emitting flash light of a predetermined guide number; A step of acquiring a flash non-flash image captured without emitting lash light, a step of acquiring a shutter speed, a subject distance, and a guide number at the time of capturing the flash flash image and the flash non-flash image, respectively; Calculating a flash light arrival amount from a difference between the flash emission image and the flash non-light emission image, and the image is based on the acquired guide number and subject distance and the calculated flash light arrival amount. The aperture value at the time of imaging is estimated.

  In the image processing method according to still another aspect of the present invention, the step of correcting the white balance includes a step of determining whether the subject is an outdoor subject during the day based on the detected brightness of the subject. The correction content of the white balance correction of the image is changed according to the result. This makes it possible to perform white balance correction with high accuracy according to the brightness of the subject.

In the image processing method according to still another aspect of the present invention, the step of estimating the aperture value includes the step of acquiring the sensitivity at which the amount of flash light reaches the appropriate exposure amount, and the sensitivity coefficient corresponding to the acquired sensitivity is obtained. K, where the acquired guide number and subject distance are GN and D, respectively, the estimated aperture value F is
F = GN × K ÷ D
Calculated by

  An image processing program according to still another aspect of the present invention causes a computer to execute the above image processing method.

  According to the present invention, the brightness of the subject is detected based on the image captured by the imaging device, the aperture value at the time of capturing, and the shutter speed, and the white balance of the image captured based on the detected brightness of the subject is determined. In order to correct, white balance correction with high accuracy according to the brightness of the subject can be performed. Especially when the interchangeable lens cannot obtain the aperture value of the lens at the time of imaging from the interchangeable lens because it is a third-party interchangeable lens, old lens, etc. Since the aperture value at the time of imaging is estimated based on the shutter speed, the subject distance, the guide number of the flash light at the time of shooting the flash emission image, and the amount of flash light reached, the aperture value of the lens at the time of imaging from the interchangeable lens The brightness of the subject can be detected even when it is not possible to acquire the image, and the white balance correction can be performed with high accuracy according to the brightness of the subject.

The perspective view which looked at the camera system which concerns on this invention from diagonally forward Rear view of camera body The block diagram which shows embodiment of the internal structure of a camera system Block diagram showing an embodiment of an image processing apparatus A graph showing the distribution range of light source types at coordinates with the horizontal axis representing color temperature and the vertical axis representing subject luminance (EV value) The block diagram which shows embodiment of an aperture value estimation part Flow chart showing main routine of white balance correction method Flow chart showing main routine of white balance correction method

  Preferred embodiments of an image processing apparatus, an imaging apparatus, an image processing method, and an image processing program according to the present invention will be described below with reference to the accompanying drawings.

<Appearance of camera system>
FIG. 1 is a perspective view of the camera system as viewed obliquely from the front, and FIG. 2 is a rear view of the camera body.

  As shown in FIG. 1, the camera system 10 is a mirrorless digital single-lens camera or a digital single-lens reflex camera including an interchangeable lens 100 and a camera body (imaging device) 200 to which the interchangeable lens 100 can be attached and detached.

  A main body mount 260 to which the interchangeable lens 100 is attached, a finder window 20 of an optical finder, and the like are provided on the front surface of the camera main body 200. The shutter release button 22, the shutter speed dial 23, An exposure correction dial 24, a power supply lever 25, and a built-in flash 30 are provided.

  As shown in FIG. 2, a monitor 216, an optical viewfinder eyepiece 26, a MENU / OK key 27, a cross key 28, a playback button 29, and the like are mainly provided on the back of the camera body 200.

  The monitor 216 functions as a display unit that displays a live view image in the imaging mode, reproduces and displays an image captured in the playback mode, and displays various menu screens. The MENU and OK key 27 is an operation key having both a function as a menu button for instructing to display a menu on the screen of the monitor 216 and an OK button for instructing confirmation and execution of selection contents. It is. The cross key 28 is an operation unit for inputting instructions in four directions, up, down, left, and right, and functions as a button for selecting an item from the menu screen or instructing selection of various setting items from each menu. The up and down keys of the cross key 28 function as a zoom switch at the time of imaging or a playback zoom switch in the playback mode, and the left key and the right key are frame advance (forward and reverse) buttons in the playback mode. Function as. The playback button 29 is a button for switching to a playback mode in which a captured still image or moving image is displayed on the monitor 216.

<Internal configuration of camera system>
FIG. 3 is a block diagram showing an embodiment of the internal configuration of the camera system 10.

[interchangeable lens]
The interchangeable lens 100 constituting the camera system 10 is manufactured in accordance with the communication standard of the camera body 200, and is an interchangeable lens that can communicate with the camera body 200 as described later. The interchangeable lens 100 includes an imaging optical system 102, a zoom lens control unit 114, a focus lens control unit 116, an aperture control unit 118, a lens side CPU (Central Processing Unit) 120 (lens side control unit), and a flash ROM (Read Only Memory). ) 126, a lens side communication unit 150, and a lens mount 160.

  The imaging optical system 102 includes a plurality of optical members including a zoom lens 104, a focus lens 106, and a diaphragm 108. The zoom lens control unit 114 controls the zoom position of the zoom lens 104 in accordance with a command from the lens side CPU 120. The focus lens control unit 116 controls the focus position of the focus lens 106 in accordance with a command from the lens side CPU 120. The diaphragm control unit 118 controls the diaphragm 108 (aperture area) in accordance with a command from the lens side CPU 120.

  The lens-side CPU 120 controls the interchangeable lens 100 as a whole, and includes a ROM 124 and a RAM 122.

  The flash ROM 126 is a nonvolatile memory that stores programs downloaded from the camera body 200.

  The lens side CPU 120 performs overall control of each part of the interchangeable lens 100 using a RAM (Random Access Memory) 122 as a work area in accordance with a control program stored in the ROM 124 or the flash ROM 126.

  The lens side communication unit 150 is connected to the camera body 200 via a plurality of signal terminals (lens side signal terminals) provided on the lens mount 160 in a state where the lens mount 160 is attached to the body mount 260 of the camera body 200. Communication. That is, the lens side communication unit 150 transmits and receives a request signal and a response signal to and from the main body side communication unit 250 of the camera main body 200 connected via the lens mount 160 and the main body mount 260 in accordance with a command from the lens side CPU 120. (Bidirectional communication).

  The interchangeable lens 100 also includes a detection unit (not shown) that detects lens information (zoom information of the zoom lens 104, focus position information of the focus lens 106, and aperture information) of each optical member of the imaging optical system 102. ing. Here, the zoom information is information indicating the zoom position, zoom magnification, focal length, and the like, and the aperture information is information indicating the aperture value (F value), the aperture diameter of the aperture 108, and the like. Hereinafter, in this example, an F value is used as aperture information.

  In order to respond to the lens information request from the camera body 200, the lens-side CPU 120 preferably stores various types of detected lens information in the RAM 122. In addition, the lens information of each optical member is detected when there is a request for lens information from the camera body 200, or is detected when the optical member is driven, or a certain period (much more than the frame period of a moving image). It is detected at a short cycle) and the detection result can be held.

[Camera body (imaging device)]
A camera body (imaging device) 200 constituting the camera system 10 includes an imaging device (imaging unit) 201 that functions as an image acquisition unit, an imaging device control unit 202, an analog signal processing unit 203, and A / D (Analog / Digital) conversion. 204, image input controller 205, digital signal processing unit 206, RAM 207, compression / decompression processing unit 208, media control unit 210, memory card 212, display control unit 214, monitor 216, main body side CPU 220, operation unit 222, clock unit 224 , Flash ROM 226, ROM 228, AF detection unit 230, brightness detection unit 232, white balance correction unit 234, wireless communication unit 236, GPS (Global Positioning System) reception unit 238, power supply control unit 240, battery 242, main body side communication unit 250, a body mount 260 that functions as a lens mounting portion, Constituting the built-in flash 30 (FIG. 1) includes a flash light emitting portion 270 and a flash control unit 272.

  The image sensor 201 is constituted by a complementary metal-oxide semiconductor (CMOS) type color image sensor. The image sensor 201 is not limited to a CMOS type, but may be an XY address type or a CCD (Charge Coupled Device) type image sensor.

  The image sensor 201 is composed of a plurality of pixels arranged in a matrix with a predetermined pattern arrangement (Bayer arrangement, X-Trans (registered trademark) arrangement, honeycomb arrangement, etc.), and each pixel has a microlens, red (R) , Green (G) or blue (B) color filter, and a photoelectric conversion unit (photodiode or the like).

  The optical image of the subject imaged on the light receiving surface of the image sensor 201 by the imaging optical system 102 of the interchangeable lens 100 is converted into an electrical signal by the image sensor 201.

  The image sensor control unit 202 controls the image capturing timing, exposure time, and the like of the image sensor 201 in accordance with instructions from the main body CPU 220. The analog signal processing unit 203 performs various types of analog signal processing on an analog image signal obtained by imaging a subject with the image sensor 201. The analog signal processing unit 203 includes a sampling hold circuit, a color separation circuit, an AGC circuit, and the like. The AGC circuit functions as a sensitivity adjustment unit that adjusts the sensitivity at the time of imaging (ISO: International Organization for Standardization), adjusts the gain of an amplifier that amplifies the input image signal, and the signal level of the image signal is Try to be in the proper range. The A / D converter 204 converts the analog image signal output from the analog signal processing unit 203 into a digital image signal.

  Image data (mosaic image data) for each pixel of RGB output via the image sensor 201, the analog signal processing unit 203, and the A / D converter 204 when capturing a still image or a moving image is transferred from the image input controller 205 to the RAM 207. Is temporarily stored. When the image sensor 201 is a CMOS image sensor, the analog signal processor 203 and the A / D converter 204 are often built in the image sensor 201.

  The digital signal processing unit 206 performs various types of digital signal processing on the image data stored in the RAM 207. The digital signal processing unit 206 in this example appropriately reads image data stored in the RAM 207, and performs offset processing, gain control processing including sensitivity correction, gamma correction processing, demosaicing processing (demosaicing) on the read image data. Digital signal processing such as RGB / YCrCb conversion processing and the like, and image data after the digital signal processing is stored in the RAM 207 again. Note that the demosaic process is a process of calculating color information of all RGB for each pixel from a mosaic image composed of RGB, for example, in the case of an imaging device composed of RGB color filters, and mosaic data (dot sequential RGB data). ) To generate the RGB 3 plane image data. The RGB / YCrCb conversion process is a process of converting the synchronized RGB data into luminance data (Y) and color difference data (Cr, Cb).

  The compression / decompression processing unit 208 performs compression processing on the uncompressed luminance data Y and color difference data Cb, Cr once stored in the RAM 207 when recording a still image or a moving image. In the case of a still image, the image is compressed in, for example, JPEG (Joint Photographic coding Experts Group) format. Compress in H.264 format. The image data compressed by the compression / decompression processing unit 208 is recorded on the memory card 212 via the media control unit 210. In addition, the compression / decompression processing unit 208 performs decompression processing on the compressed image data obtained from the memory card 212 via the media control unit 210 in the playback mode, and generates uncompressed image data.

  The media control unit 210 performs control to record the image data compressed by the compression / decompression processing unit 208 in the memory card 212. In addition, the media control unit 210 performs control for reading compressed image data from the memory card 212.

  The display control unit 214 performs control to display uncompressed image data stored in the RAM 207 on the monitor 216. The monitor 216 is configured by a display device such as a liquid crystal display device or organic electroluminescence.

  When displaying a live view image on the monitor 216, digital image signals continuously generated by the digital signal processing unit 206 are temporarily stored in the RAM 207. The display control unit 214 converts the digital image signal temporarily stored in the RAM 207 into a display signal format and sequentially outputs it to the monitor 216. Thereby, a captured image is displayed on the monitor 216 in real time, and the monitor 216 can be used as an electronic viewfinder.

  The shutter release button 22 is an operation means for inputting an instruction to start imaging, and is configured by a two-stage stroke type switch composed of so-called “half press” and “full press”.

  In the still image capturing mode, an S1 ON signal is output when the shutter release button 22 is pressed halfway, an S2 ON signal is output when the shutter release button 22 is further pressed halfway down, and an S1 ON signal is output. Then, the camera body 200 executes imaging preparation processing such as automatic focus adjustment (AF processing) and automatic exposure control (AE processing). When the S2 ON signal is output, the camera body 200 executes still image imaging processing and recording processing. To do. The AF process and the AE process are automatically performed when the auto mode is set by the operation unit 222, and the AF process and the AE process are not performed when the manual mode is set. Needless to say.

  In the moving image capturing mode, when the S2 ON signal is output when the shutter release button 22 is fully pressed, the camera body 200 enters a moving image recording mode in which recording of a moving image is started. When the shutter release button 22 is fully pressed again and an S2 ON signal is output, the camera body 200 enters a standby state and pauses the moving image recording process.

  The shutter release button 22 is not limited to a two-stroke type switch that is half-pressed and fully-pressed, and an S1 ON signal and an S2 ON signal may be output by a single operation. May be provided to output an S1 on signal and an S2 on signal.

  Further, in the form in which the operation instruction is performed using the touch panel or the like, the operation instruction may be output by touching an area corresponding to the operation instruction displayed on the screen of the touch panel as the operation unit. The form of the operation means is not limited to these as long as it instructs the preparation process and the imaging process.

  The still image or moving image acquired by the imaging is compressed by the compression / decompression processing unit 208, and the compressed image data includes the required attachment of the imaging date and time, GPS information, and imaging conditions (F value, shutter speed, ISO sensitivity, etc.). After the information is added to the image file, it is stored in the memory card 212 via the media control unit 210.

  The main body side CPU 220 controls the overall operation of the camera main body 200 and the driving of the optical members of the interchangeable lens 100, and based on inputs from the operation unit 222 including the shutter release button 22 and the like, The interchangeable lens 100 is controlled.

  The clock unit 224 measures time based on a command from the main body CPU 220 as a timer. The clock unit 224 measures the current date and time as a calendar.

  The flash ROM 226 is a non-volatile memory that can be read and written, and stores setting information.

  The ROM 228 stores a camera control program executed by the main body side CPU 220, defect information of the image sensor 201, various parameters and tables used for image processing, and the like. The main body side CPU 220 controls each part of the camera main body 200 and the interchangeable lens 100 while using the RAM 207 as a work area according to the camera control program stored in the ROM 228.

  The AF detection unit 230 calculates a numerical value necessary for AF control based on the digital image signal. In the case of so-called contrast AF, for example, an integrated value (focus evaluation value) of high-frequency components of the G signal in a predetermined AF area is calculated. The main body side CPU 220 moves the focus lens 106 to a position where the focus evaluation value is maximized during AF control (that is, a position where the contrast is maximized). Note that AF is not limited to contrast AF. For example, a defocus amount is detected based on pixel data of phase difference detection pixels provided in the image sensor, and focus is performed so that the defocus amount becomes zero. A phase difference AF for moving the lens 106 may be performed.

  The brightness detection unit 232 is a part that detects the brightness of the subject (subject brightness), and calculates a numerical value (exposure value (EV value)) necessary for AE control corresponding to the subject brightness. The CPU 220 determines the F value, the shutter speed, and the ISO sensitivity from a predetermined program diagram based on the EV value obtained from the brightness detection unit 232 during the AE control.

  The white balance correction unit 234 calculates white balance gains (WB (White Balance) gains) Gr, Gg, Gb for each color data of RGB data (R data, G data, and B data). White balance correction is performed by multiplying the B data by the calculated WB gains Gr, Gg, and Gb, respectively. Here, as a method for calculating the WB gains Gr, Gg, and Gb, the light source type that illuminates the subject is specified based on the brightness (EV value) of the subject, the color temperature of the ambient light, and the like. A method of reading out a WB gain corresponding to a specified light source type from a storage unit in which an appropriate WB gain is stored can be considered, but other known methods for obtaining WB gains Gr, Gg, Gb using at least an EV value are conceivable. Methods (Japanese Patent Laid-Open Nos. 2000-224608 and 2003-224863) are conceivable. Details of the white balance correction unit 234 will be described later.

  The wireless communication unit 236 is a part that performs short-range wireless communication of a standard such as Wi-Fi (Wireless Fidelity) (registered trademark), Bluetooth (registered trademark), etc., and with a peripheral digital device (a mobile terminal such as a smartphone). Necessary information is sent and received between the two.

  The GPS receiving unit 238 receives GPS signals transmitted from a plurality of GPS satellites in accordance with instructions from the main body CPU 220, executes positioning calculation processing based on the received plurality of GPS signals, and performs the latitude, longitude, And GPS information consisting of altitude is acquired. The acquired GPS information can be recorded in the header of the image file as attached information indicating the imaging position of the captured image.

  The power supply control unit 240 supplies the power supply voltage supplied from the battery 242 to each unit of the camera main body 200 in accordance with a command from the main body CPU 220. In addition, the power supply control unit 240 supplies the power supply voltage supplied from the battery 242 to each unit of the interchangeable lens 100 via the main body mount 260 and the lens mount 160 in accordance with a command from the main body side CPU 220.

  The lens power switch 244 switches on and off the power supply voltage applied to the interchangeable lens 100 via the main body mount 260 and the lens mount 160 and switches the level in accordance with a command from the main body side CPU 220.

  The main body side communication unit 250 transmits and receives request signals and answer signals to and from the lens side communication unit 150 of the interchangeable lens 100 connected via the main body mount 260 and the lens mount 160 in accordance with a command from the main body side CPU 220 (both Communication). The main body mount 260 is provided with a plurality of terminals 260A as shown in FIG. 1, and when the interchangeable lens 100 is attached to the camera main body 200 (the lens mount 160 and the main body mount 260 are connected), the main body A plurality of terminals 260A (FIG. 1) provided on the mount 260 and a plurality of terminals (not shown) provided on the lens mount 160 are electrically connected, and the main body side communication unit 250 and the lens side communication unit 150 are connected. Bi-directional communication is possible.

  The built-in flash 30 (FIG. 1) is, for example, a TTL (Through The Lens) automatic dimming flash, and includes a flash light emitting unit 270 and a flash control unit 272.

  The flash control unit 272 has a function of adjusting the light emission amount (guide number) of flash light emitted from the flash light emitting unit 270. That is, the flash control unit 272 causes the flash light emitting unit 270 to emit light in synchronization with the flash imaging instruction from the main body side CPU 220, and the reflected light (including ambient light) incident through the imaging optical system 102 of the interchangeable lens 100. Photometry is started, and when the photometric value reaches the standard exposure value, the flash light emission from the flash light emitting unit 270 is stopped.

[Image processing device]
FIG. 4 is a block diagram showing an embodiment of the image processing apparatus 280 according to the present invention.

  The image processing apparatus 280 illustrated in FIG. 4 mainly includes an aperture value acquisition unit 282, an aperture value estimation unit 284, a brightness detection unit 232, and a white balance correction unit 234.

  The aperture value acquisition unit 282 acquires the aperture value (F value) of the aperture used when imaging the interchangeable lens attached to the camera body 200. In this example, the interchangeable lens 100 is communicated with the interchangeable lens. The main body mount 260 and the main body side communication unit 250 (FIG. 3) that acquire various lens information from the lens function as the aperture value acquisition unit 282.

  The aperture value estimation unit 284 estimates the F value when the aperture value acquisition unit 282 cannot acquire the F value at the time of imaging from the interchangeable lens attached to the camera body 200. The main body CPU 220 functions as the aperture value estimation unit 284. Details of the aperture value estimation unit 284 will be described later.

  The F value acquired by the aperture value estimation unit 284 or the F value estimated by the aperture value estimation unit 284 is added to the brightness detection unit 232.

  Information indicating image data, shutter speed, and ISO sensitivity is added to other inputs of the brightness detection unit 232, and the brightness detection unit 232 determines the brightness (EV value) of the subject based on these inputs. Is calculated. Note that the image data input to the brightness detection unit 232 is image data indicating a live view image captured in real time or image data captured when the shutter release button 22 is half-pressed, and the digital signal processing unit 206. This is the image data after the gamma correction by. The shutter speed, the ISO sensitivity information, and the F value input from the aperture value acquisition unit 282 are those at the time of image data input to the brightness detection unit 232.

The brightness detection unit 232 calculates the average value (average value represented by 8 bits (0 to 255)) of luminance data generated from G data or RGB data in the input image data (RGB data) as Y _{If av} , the subject brightness (subject brightness) EV is calculated by the following equation.

[Equation 1]
EV = EVo + log ₂ (Y _av / 118)
In the above [Equation 1], EVo is an imaging EV value at the time of image data acquisition, and can be obtained by the following equation when the ISO sensitivity at the time of imaging is ISO100.

[Equation 2]
EVo = AV + TV
In the above [Expression 2], AV (Aperture Value) is a value corresponding to the F value, and TV (Time Value) is a value corresponding to the shutter speed. The brightness detection unit 232 can obtain an imaging EV value (EVo) according to the equation [2] based on information indicating the input F value, shutter speed, and ISO sensitivity.

  In the equation 1, 118 is luminance data (luminance data after gamma correction) of a subject having 18% reflectance (average reflectance of the object field) at the time of proper exposure (hereinafter referred to as “18% gray”). ) In 8 bits.

  The brightness detection unit 232 outputs the subject luminance (EV value) calculated by the above [Equation 1] to the white balance correction unit 234.

  The white balance correction unit 234 includes a gain correction unit 234A, a WB gain calculation unit 234B, and a light source estimation unit 234C that are mainly configured by a multiplier.

  Image data (RGB data) before white balance correction is added to one input of the gain correction unit 234A, and WB gain Gr, Gg, Gb for each RGB color from the WB gain calculation unit 234B to the other input. The gain correction unit 234A performs white balance correction by multiplying the input RGB data (R data, G data, and B data) by the WB gains Gr, Gg, and Gb for each color.

  The calculation of the WB gains Gr, Gg, and Gb by the WB gain calculation unit 234B is based on the light source type that illuminates the subject estimated by the light source estimation unit 234C, and an appropriate WB gain is stored in advance for each light source type. This is done by reading the WB gain corresponding to the estimated light source type from the storage unit 235.

  Next, the light source estimation unit 234C will be described.

  The subject luminance (EV value) detected by the brightness detection unit 232 is added to one input of the light source estimation unit 234C, and image data (RGB data) before white balance correction is added to the other input. The light source estimation unit 234C estimates the type of light source (light source type) that illuminates the subject based on these inputs.

  FIG. 5 is a graph showing the distribution range of light source types at coordinates with the color temperature as the horizontal axis and the subject luminance (EV value) as the vertical axis.

  The light source estimation unit 234C determines whether or not the subject imaged based on the input EV value is an outdoor subject in the daytime (that is, whether or not the light source that illuminates the subject is an outdoor light source in the daytime). It has.

  As shown in FIG. 5, the daytime outdoor light source (sunlight) has a higher EV value than other light sources (artificial light sources), and it is determined whether the light source is daytime outdoor light source based on the EV value. Is possible. When the input EV value is equal to or greater than a predetermined threshold Th (for example, 11 EV or 12 EV), the determination unit 237 can determine that the light source that illuminates the subject is a light source outdoors during the daytime.

  Further, the light source estimation unit 234C detects the color temperature of the light source that illuminates the subject based on the input RGB data. As a method for detecting the color temperature, a ratio (R: G: B) of average values obtained by integrating and averaging R data, G data, and B data, or a ratio (R: G: B) of the average values of R data and G data. / G) and a method of detecting based on the ratio (B / G) of the integrated average value of B data and G data. In addition, the detection is performed in the same manner as described in JP 2010-258703 A. May be.

  The light source estimation unit 234C has a table corresponding to the graph shown in FIG. 5, and is based on the EV value input from the brightness detection unit 232 and the color temperature calculated based on the image data before white balance correction. The light source type is estimated according to which of the light source types on the coordinates shown in FIG. 5 the coordinate determined by the EV value and the color temperature belongs.

  The light source estimation unit 234C can accurately estimate the light source type by using not only the color temperature of the subject but also the EV value of the subject. For example, as shown in FIG. 5, a daylight light source (sunny sunlight) and a daylight fluorescent lamp (artificial light source) cannot be determined only by the color temperature of the subject, but both are determined by using the EV value. can do.

  In this way, it is possible to determine whether or not the subject is an outdoor subject during the day based on the EV value of the subject, and the correction content of the white balance correction is changed according to the determination result (the light source is accurately determined according to the determination result). Since the seed is estimated and changed to the WB gain Gr, Gg, Gb corresponding to the estimated light source type), white balance correction can be performed with high accuracy.

[Aperture value estimation unit]
Next, the aperture value estimation unit 284 shown in FIG. 4 will be described in detail.

  The aperture value estimation unit 284 estimates the F value when the aperture value acquisition unit 282 cannot acquire the F value at the time of imaging from the interchangeable lens mounted on the camera body 200 as described above. The obtained F value is output to the brightness detection unit 232. Thereby, the brightness detection unit 232 can detect the subject luminance (EV value) even when the F value is not input from the aperture value acquisition unit 282.

  FIG. 6 is a block diagram illustrating an embodiment of the aperture value estimation unit 284.

  As shown in FIG. 6, the aperture value estimation unit 284 mainly includes a flash light arrival amount calculation unit 284A, a sensitivity acquisition unit 284B, a sensitivity coefficient calculation unit 284C, an imaging condition acquisition unit 284D, and an aperture value calculation unit 284E. .

  The main body side CPU 220 shown in FIG. 3 pops up the built-in flash 30 from the upper surface of the camera main body 200 when the aperture value acquisition unit 282 cannot acquire the F value at the time of imaging from the interchangeable lens attached to the camera main body 200. (See FIG. 1), the flash emission imaging in which the built-in flash 30 is emitted in synchronization with one release operation of the shutter release button 22 and the flash non-emission imaging in which the built-in flash 30 is not emitted are continuously performed. . Flash emission image data and flash non-emission image data acquired by flash emission imaging and flash non-emission imaging are temporarily stored in the RAM 207. Note that the flash light emission image data and the flash non-light emission image data temporarily stored in the RAM 207 are each subjected to gamma correction by the digital signal processing unit 206.

  The flash light arrival amount calculation unit 284A shown in FIG. 6 reads the flash light emission image data and the flash non-light emission image data from the RAM 207, and calculates the flash light arrival amount from the difference between these image data. The amount of flash light reached corresponds to the exposure amount when only the flash light is used as illumination light.

  Based on the flash light arrival amount calculated by the flash light arrival amount calculation unit 284A, the sensitivity acquisition unit 284B calculates a sensitivity (ISO sensitivity) for making the exposure amount corresponding to the arrival amount appropriate exposure.

  Specifically, the flash light arrival amount calculation unit 284A obtains average luminance data from the image data of the difference between the flash emission image data and the flash non-emission image data (image data when only the flash light is used as illumination light). calculate. This average luminance data corresponds to the amount of flash light reached. The sensitivity acquisition unit 284B obtains ISO sensitivity for converting the average luminance data into 18% gray luminance data (118 in 8 bits). For example, when the IOS sensitivity at the time of imaging of the flash emission image data and the flash non-emission image data is ISO 100 and the average luminance data calculated from the difference image data is 59, adjusting the ISO sensitivity to ISO 400 results in 18% gray. It becomes luminance data (118). In this case, the ISO sensitivity required by the sensitivity acquisition unit 284B is ISO400.

  The sensitivity coefficient calculation unit 284C calculates the sensitivity coefficient K based on the ISO sensitivity acquired (obtained) by the sensitivity acquisition unit 284B and the IOS sensitivity at the time of capturing the flash emission image data and the flash non-emission image data.

  Here, the sensitivity coefficient K can be calculated by the following equation, where IOSa is a numerical value indicating the IOS sensitivity at the time of GN calculation, and ISOb is a numerical value indicating the ISO sensitivity acquired by the sensitivity acquisition unit 284B.

  Therefore, when the IOS sensitivity at the time of imaging is ISO100 (IOSa = 100) and the ISO sensitivity acquired by the sensitivity acquisition unit 284B is ISO100 (ISOb = 100), the sensitivity coefficient K is K = 1. Similarly, the ISO sensitivities acquired by the sensitivity acquisition unit 284B are IOS200 (ISOb = 200), ISO400 (ISOb = 400), IOS800 (ISOb = 800), IOS1600 (ISOb = 1600), and ISO3200 (ISOb = 3200). In this case, the sensitivity coefficient K becomes K = 1.4, K = 2, K = 2.8, K = 4, and K = 5.6, respectively.

  Information indicating the sensitivity coefficient K calculated by the sensitivity coefficient calculation unit 284C is added to the aperture value calculation unit 284E.

  The imaging condition acquisition unit 284D acquires from the built-in flash 30 the light emission amount (guide number GN) of the flash light emitted from the built-in flash 30 for flash emission imaging. Further, the imaging condition acquisition unit 284D acquires the subject distance D at the time of flash light emission imaging and flash non-light emission imaging. A method for obtaining the subject distance D will be described later.

  Information indicating the guide number GN and subject distance D acquired by the imaging condition acquisition unit 284D is added to the aperture value calculation unit 284E.

  The aperture value calculation unit 284E calculates the F value according to the following equation based on the information indicating the sensitivity coefficient K input from the sensitivity coefficient calculation unit 284C and the information indicating the guide number GN and the subject distance D input from the imaging condition acquisition unit 284D. calculate.

[Equation 4]
F = GN × K ÷ D
Specifically, when the guide number GN = 16, the sensitivity coefficient K = 2, and the subject distance D = 4 m, F = 16 × 2 ÷ 4 = 8.

[How to get the subject distance]
Next, an embodiment of a method for acquiring the subject distance D by the imaging condition acquisition unit 284D will be described.

<First Embodiment>
In the case where the interchangeable lens is not manufactured in accordance with the communication standard of the camera body 200, for example, a third-party interchangeable lens, there is a limitation in receiving lens information from the interchangeable lens, but there are cases where focus information can be acquired. is there. For example, in the case of an interchangeable lens having a mechanical focus mechanism, there is a lens that drives a focus lens for focusing by using a motor that the camera body has. A mechanism for mechanically joining the interchangeable lens and the camera body is called a coupling. When the focus ring of the interchangeable lens is moved, the coupling rotates. The rotational position of the focus ring (corresponding to the lens position of the focus lens) when the subject is focused is read by the lens position acquisition unit via the coupling, so that the rotational position of the focus ring (that is, the lens of the focus lens). The subject distance corresponding to (position) can be acquired.

  However, it is necessary to manually input the starting point (near end) and the end point (infinity) of the rotation of the focus ring. For example, when the interchangeable lens is attached, the focus ring is manually rotated, the focus lens of the interchangeable lens is moved to the close end and infinity, and the focus ring rotation start point (closest end) and end point (infinity) Get the lens position.

  The imaging condition acquisition unit 284D acquires the subject distance from the relationship between the lens position at the close end and the infinity of the focus lens acquired as described above and the lens position of the focus lens when the subject is focused. Note that a representative distance (for example, 0.3 m) may be set as the shortest imaging distance at the closest end, or the shortest imaging distance may be set by manual input.

  Among mount adapters for enabling use of third-party interchangeable lenses and old lenses having no lens mount compatibility, there is a mount adapter that enables AF operation. In this case, since the lens position necessary for the AF operation can be acquired, an approximate distance from the lens position at the time of focusing to the subject can be acquired. In addition, when using a mount adapter that can perform AF operation, the lens position at the near end and at infinity is automatically set during the AF operation for searching the lens position of the focus lens from the close end to infinity. Can be acquired.

<Second Embodiment>
Even if not all lens information can be acquired from the interchangeable lens, information on the focal length of the interchangeable lens may be acquired. For example, when the product code of the interchangeable lens can be acquired, the focal length information can be acquired from the product code of the interchangeable lens.

  In this case, the camera body 200 is provided with a subject distance estimation unit that estimates the distance to the predetermined subject (subject distance) based on the focal length information of the interchangeable lens and the size of the image of the predetermined subject whose size is known. The imaging condition acquisition unit 284D can acquire the subject distance estimated by the subject distance estimation unit from the subject distance estimation unit.

  That is, when the subject is in focus, the size of the subject and the size of the subject on the image (imaging surface) have a one-to-one correspondence. Therefore, when the size of the subject and the focal length of the lens are known, the subject distance can be calculated based on the size of the subject, the focal length, and the size of the subject on the imaging surface. As a subject whose size is known, a human face is suitable. However, the subject is not limited to this, and any subject may be used as long as the size of the subject to be imaged or a part of the subject is a known size. But you can.

<Third Embodiment>
Some smartphones and digital cameras have a communication function (such as Wi-Fi or bluetooth) for performing short-range wireless communication.

  When the subject has a mobile terminal such as a smartphone that can communicate, the mobile terminal (possibly holding the mobile terminal) is detected by detecting the strength of radio waves during wireless communication between the camera body 200 and the mobile terminal that the subject has. The distance to the subject) can be estimated.

  Therefore, the imaging condition acquisition unit 284D can acquire the subject distance based on the strength of the radio wave received from the mobile terminal when the wireless communication unit 236 of the camera body 200 is wirelessly communicating with the mobile terminal.

  In this case, it is necessary to grasp the reference radio wave intensity in advance. For example, in addition to a method in which the radio wave intensity is detected in advance in a state where the camera body 200 and the mobile terminal are close to each other and the detected radio wave intensity is used as a reference radio wave intensity, the radio wave intensity that is generally spread by countries and regions It is conceivable that the standard is 10 mW in Japan.

<Fourth Embodiment>
Some smartphones and digital cameras include a GPS receiving unit in addition to a communication function for performing short-range wireless communication, and can acquire GPS information including latitude, longitude, and altitude.

  The GPS information acquired by the smartphone or the like that the subject has is acquired by wireless communication or the like on the camera body 200 side, and the acquired GPS information (position information of the subject at the time of imaging) and the GPS reception unit 238 of the camera body 200 are acquired. Based on the obtained GPS information (position information of the camera body 200 at the time of imaging), the subject distance can be calculated from the latitude, longitude, and altitude of the difference between these two GPS information.

  The imaging condition acquisition unit 284D includes GPS information indicating the position of the subject acquired via the GPS information acquisition unit (wireless communication unit 236) and GPS information indicating the imaging position acquired by the GPS reception unit 238 of the camera body 200. The subject distance can be acquired based on the result.

<Fifth Embodiment>
There is a system that sends information such as advertisements and explanations to a person who stands at a specific spot (in front of a product or painting) in a sightseeing spot or museum. In this system, for example, a spotlight is made of a light-emitting diode and information is transmitted by causing the light-emitting diode to blink at high speed, and the customer confirms the information by receiving light that blinks at high speed on a smartphone or dedicated terminal. It is a system that can.

  When imaging a specific spot (fixed subject), the system is used, and position information (for example, GPS information) indicating the position of the specific spot is transmitted by wireless communication from the transmission unit (position information transmission unit) of the system. Receive. When receiving position information by optical wireless communication, it is necessary to provide an optical wireless communication unit in the camera body 200. However, when the system transmits information by normal wireless communication, Position information indicating the position of a specific spot can be acquired using the wireless communication unit 236.

  The imaging condition acquisition unit 284D determines the distance (subject distance) to the specific spot based on the position information indicating the position of the specific spot and the position information of the camera body 200 (GPS information acquired by the GPS reception unit 238). Can be acquired.

[Image processing method]
Next, an image processing method according to the present invention will be described.

  7 and 8 are flowcharts showing embodiments of the image processing method according to the present invention, respectively, and particularly show a white balance correction method for performing white balance correction on a captured image.

  FIG. 7 is a flowchart showing a main routine of the white balance correction method. In FIG. 7, the camera body 200 determines whether or not the F value can be acquired from the interchangeable lens (step S10). If the camera body 200 cannot communicate with the attached interchangeable lens, the camera body 200 determines that the F value cannot be acquired from the interchangeable lens.

  If it is determined that the F value can be acquired from the interchangeable lens (in the case of “Yes”), the camera body 200 acquires the F value of the interchangeable lens via the body mount 260 and the body side communication unit 250 (step S12). ). On the other hand, if it is determined that the F value cannot be acquired from the interchangeable lens (in the case of “No”), the camera body 200 calculates (estimates) the F value of the interchangeable lens (step S14).

  FIG. 8 is a flowchart showing a subroutine showing the processing content of step S12 in FIG. 7, and the F value of the interchangeable lens is calculated according to the following procedure.

  In FIG. 8, subject distance D, ISO sensitivity, shutter speed, and guide number GN are acquired as imaging conditions at the time of imaging (step S30).

  Subsequently, the flash emission imaging that causes the built-in flash 30 to emit light and the flash non-emission imaging that does not cause the built-in flash 30 to emit light are continuously performed to obtain a flash emission image and a flash non-emission image (steps S32 and S34). .

  The flash light arrival amount calculation unit 284A calculates the flash light arrival amount from the difference between the flash emission image and the flash non-emission image acquired in steps S32 and S34 (step S36).

  Based on the flash light arrival amount calculated in step S36, it is determined whether or not the luminance corresponding to the flash light arrival amount is 18% gray (step S38). If the luminance is not 18% gray (in the case of “No”), the sensitivity acquisition unit 284B adjusts the ISO sensitivity to obtain the ISO sensitivity to obtain the luminance of 18% gray (step S40).

  Next, the sensitivity coefficient calculation unit 284C calculates the sensitivity coefficient K based on the above-described Expression 3 based on the ISO sensitivity at the time of imaging acquired in step S30 and the ISO sensitivity adjusted in step S40 ( Step S42).

  The aperture value calculation unit 284E calculates the F value based on the equation [4] based on the guide number GN and subject distance D of the built-in flash 30 acquired in step S30 and the sensitivity coefficient K calculated in step S42. (Step S44).

  Returning to the main routine of FIG. 7, in step S16, the F value acquired in step S12 or the F value calculated (estimated) in step S14, the imaging conditions (shutter speed, ISO sensitivity) at the time of imaging, and the imaging are performed. An exposure value (EV value) indicating the brightness of the subject is calculated based on the image data.

  Subsequently, it is determined whether or not the calculated exposure value is equal to or greater than a threshold Th (for example, 11 EV or 12 EV) for determining whether or not it is outdoors during the day (step S18).

  When it is determined that the environment during imaging is outdoor during the daytime (if “Yes”), daytime outdoor AWB control is performed using the WB gain corresponding to the daytime outdoor light source type (step S20). .

  On the other hand, if it is determined that the environment during imaging is not outdoor during the daytime (if “No”), AWB control other than the daytime outdoor AWB control (AWB control using the WB gain corresponding to the light source type of the artificial light source) (Step S22).

[Others]
The present invention relates to an image processing program that causes a computer to function as an image processing apparatus by being installed in a general-purpose computer, a recording medium in which the image processing program is recorded, and a computer in which the image processing program is installed (image processing apparatus) )including.

  In the case of a computer functioning as an image processing apparatus, raw data before image processing indicating a flash light emission image, a flash non-light emission image, or the like is acquired via an imaging device, a memory card, or a communication line.

  Although the camera body 200 of this embodiment includes the built-in flash 30, the image pickup apparatus according to the present invention may not include the built-in flash 30, and in this case, an external attachment attached to the accessory shoe. A flash can be used.

  Further, when the F value is estimated to detect the brightness of the subject, the flash emission image and the flash emission image are acquired, but the white balance correction is performed for both the flash emission image and the flash emission image. Or may be performed on any one of the images. Furthermore, after the F value is estimated and the brightness of the subject is detected, imaging is performed again based on the imaging EV value based on the detected brightness of the subject, and white balance correction is performed on the captured image. Also good.

  Moreover, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Camera system, 22 ... Shutter release button, 100 ... Interchangeable lens, 102 ... Shooting optical system, 104 ... Zoom lens, 106 ... Focus lens, 108 ... Aperture, 120 ... Lens side CPU, 122, 207 ... RAM, 124, 228 ... ROM, 126, 226 ... Flash ROM, 150 ... Lens side communication unit, 160 ... Lens mount, 200 ... Camera body (imaging device), 201 ... Image sensor, 203 ... Analog signal processing unit, 206 ... Digital signal processing unit , 212 ... Memory card, 216 ... Monitor, 220 ... Main body side CPU, 222 ... Operation unit, 232 ... Brightness detection unit, 234 ... White balance correction unit, 234A ... Gain correction unit, 234B ... WB gain calculation unit, 234C ... Light source estimation unit, 235 ... storage unit, 236 ... wireless communication unit, 237 ... size , 238 ... GPS receiver, 250 ... main body side communication part, 260 ... main body mount, 270 ... flash light emission part, 272 ... flash control part, 282 ... aperture value acquisition part, 284 ... aperture value estimation part, 284A ... flash light Achieving amount calculation unit, 284B ... sensitivity acquisition unit, 284C ... sensitivity coefficient calculation unit, 284D ... imaging condition acquisition unit, 284E ... aperture value calculation unit

Claims (16)

An aperture value at the time of imaging an image of a subject imaged by an interchangeable lens-equipped imaging device equipped with an interchangeable lens, and an aperture value acquisition unit that acquires the aperture value from the interchangeable lens;
An aperture value estimation unit that estimates an aperture value when the aperture value acquisition unit cannot acquire an aperture value at the time of imaging from the interchangeable lens;
Brightness detection that detects the brightness of the subject based on the image captured by the imaging device, the aperture value acquired by the aperture value acquisition unit or the aperture value estimated by the aperture value estimation unit, and the shutter speed at the time of imaging And
A white balance correction unit that corrects the white balance of the captured image based on the brightness of the subject detected by the brightness detection unit,
The aperture value estimation unit
An image captured by the imaging device, each obtained by emitting a flash light of a predetermined guide number and captured by a flash light, and a non-flash image captured by emitting no flash light An image acquisition unit;
An imaging condition acquisition unit that acquires a shutter speed, a subject distance, and the guide number at the time of imaging the flash emission image and the flash non-emission image;
A flash light arrival amount calculation unit that calculates the amount of flash light reached from the difference between the flash emission image acquired by the image acquisition unit and the flash non-emission image,
An image for estimating an aperture value at the time of imaging of the image based on the guide number and the subject distance acquired by the imaging condition acquisition unit and the flash light arrival amount calculated by the flash light arrival amount calculation unit Processing equipment.   The white balance correction unit includes a determination unit that determines whether or not the subject is an outdoor subject during the day based on the brightness of the subject detected by the brightness detection unit, and the image according to the determination result by the determination unit The image processing apparatus according to claim 1, wherein the correction content of the white balance correction is changed. The aperture value estimation unit includes a sensitivity acquisition unit that acquires sensitivity at which the amount of flash light reached reaches an appropriate exposure amount, the sensitivity coefficient corresponding to the acquired sensitivity is K, and the imaging condition acquisition unit acquires the sensitivity coefficient Assuming that the guide number and the subject distance are GN and D, respectively, the estimated aperture value F is expressed by the following equation:
F = GN × K ÷ D
The image processing apparatus according to claim 1, wherein the image processing apparatus is calculated by: A lens mounting part to which the interchangeable lens can be attached and detached,
An imaging unit that captures an image of a subject through an interchangeable lens mounted on the lens mounting unit;
An aperture value acquisition unit for acquiring an aperture value at the time of imaging from the interchangeable lens mounted on the lens mounting unit;
An aperture value estimation unit that estimates an aperture value at the time of imaging when the aperture value acquisition unit cannot acquire an aperture value at the time of imaging from the interchangeable lens mounted on the lens mounting unit;
Brightness detection that detects the brightness of the subject based on the image captured by the imaging unit, the aperture value acquired by the aperture value acquisition unit or the aperture value estimated by the aperture value estimation unit, and the shutter speed at the time of imaging And
A white balance correction unit that corrects the white balance of the image captured by the imaging unit based on the brightness of the subject detected by the brightness detection unit,
The aperture value estimation unit
An image captured by the imaging unit, which is obtained by emitting flash light of a predetermined guide number and captured by flash light, and non-flash image captured by emitting flash light without emitting flash light, respectively. An image acquisition unit;
An imaging condition acquisition unit that acquires a shutter speed, a subject distance, and the guide number at the time of imaging the flash emission image and the flash non-emission image;
A flash light arrival amount calculation unit that calculates the amount of flash light reached from the difference between the flash emission image acquired by the image acquisition unit and the flash non-emission image,
Imaging that estimates an aperture value at the time of imaging of the image based on the guide number and the subject distance acquired by the imaging condition acquisition unit and the flash light arrival amount calculated by the flash light arrival amount calculation unit apparatus. The interchangeable lens mounted on the lens mounting unit and a communication unit capable of communicating via the lens mounting unit,
The imaging apparatus according to claim 4, wherein the aperture value acquisition unit acquires the aperture value of the interchangeable lens via the communication unit when the communication unit can communicate with the interchangeable lens.   The white balance correction unit includes a determination unit that determines whether or not the subject is an outdoor subject during the day based on the brightness of the subject detected by the brightness detection unit, and the image according to the determination result by the determination unit The imaging apparatus according to claim 4, wherein the correction content of the white balance correction is changed. The aperture value estimation unit includes a sensitivity acquisition unit that acquires sensitivity at which the amount of flash light reached reaches an appropriate exposure amount, the sensitivity coefficient corresponding to the acquired sensitivity is K, and the imaging condition acquisition unit acquires the sensitivity coefficient Assuming that the guide number and the subject distance are GN and D, respectively, the estimated aperture value F is expressed by the following equation:
F = GN × K ÷ D
The imaging device according to claim 4, which is calculated by: A lens position acquisition unit that acquires the lens position of the focus lens of the interchangeable lens when focused on a subject;
The imaging apparatus according to claim 4, wherein the imaging condition acquisition unit acquires the subject distance based on a lens position of the focus lens acquired by the lens position acquisition unit. The distance to the predetermined subject is estimated based on the focal length information of the interchangeable lens and the size of the predetermined subject in the captured image when the predetermined subject having a known size is focused. With a subject distance estimation unit,
The imaging apparatus according to claim 4, wherein the imaging condition acquisition unit acquires the subject distance estimated by the subject distance estimation unit from the subject distance estimation unit. A wireless communication unit that wirelessly communicates with the mobile terminal that the subject has,
The imaging apparatus according to claim 4, wherein the imaging condition acquisition unit acquires the subject distance based on an intensity of radio waves received from the mobile terminal by the wireless communication unit. A GPS information acquisition unit for acquiring GPS information;
8. The apparatus according to claim 4, wherein the imaging condition acquisition unit acquires the subject distance based on GPS information indicating the position of the subject acquired by the GPS information acquisition unit and GPS information indicating the imaging position. The imaging device described. A wireless communication unit that receives the position information from a position information transmission unit that transmits position information indicating the position of a fixed subject;
8. The apparatus according to claim 4, wherein the imaging condition acquisition unit acquires the subject distance based on position information indicating a position of a fixed subject acquired by the wireless communication unit and position information indicating an imaging position. The imaging device described in 1. An aperture value at the time of imaging an image of a subject imaged by an interchangeable lens-equipped imaging device equipped with an interchangeable lens, and obtaining the aperture value from the interchangeable lens; and
Estimating the aperture value when the aperture value at the time of imaging cannot be acquired from the interchangeable lens by the step of acquiring the aperture value;
Detecting the brightness of the subject based on the image captured by the imaging device, the acquired aperture value or the estimated aperture value, and the shutter speed at the time of imaging;
Correcting a white balance of the captured image based on the detected brightness of the subject,
The step of estimating the aperture value includes
An image captured by the imaging device, each obtained by emitting a flash light of a predetermined guide number and captured by a flash light, and a non-flash image captured by emitting no flash light Steps,
Obtaining a shutter speed, a subject distance and the guide number at the time of capturing the flash emission image and the flash non-emission image, respectively;
Calculating the amount of flash light reached from the difference between the acquired flash emission image and the flash non-emission image,
An image processing method for estimating an aperture value at the time of capturing the image based on the acquired guide number and the subject distance and the calculated amount of the flash light reached.   The step of correcting the white balance includes a step of determining whether or not the subject is an outdoor subject during the day based on the brightness of the detected subject, and the white balance correction of the image is performed according to the determined determination result. The image processing method according to claim 13, wherein the correction content is changed. The step of estimating the aperture value includes the step of acquiring a sensitivity at which the amount of flash light reached becomes an appropriate exposure amount, and the sensitivity coefficient corresponding to the acquired sensitivity is K, the acquired guide number and the subject. When the distances are GN and D, respectively, the estimated aperture value F is expressed by the following equation:
F = GN × K ÷ D
The image processing method according to claim 13 or 14 calculated by:   An image processing program for causing a computer to execute the image processing method according to any one of claims 13 to 15.

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