JP4682104B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus using a photoelectric conversion element such as a digital camera and a control method thereof, and more specifically, corrects the influence of foreign matter such as dust on an optical member arranged in front of the imaging element from the captured image data. The present invention relates to an imaging apparatus and a control method thereof.

  In an interchangeable lens digital camera, dust or the like floating in the air may enter the camera body when the lens is removed from the camera body. In addition, various mechanical units such as a shutter mechanism are disposed inside the camera. By operating these mechanical units, dust such as metal pieces is generated in the camera body. In some cases. If such foreign matter such as dust or dust adheres to the surface of the image sensor that constitutes the imaging unit of the digital camera, the foreign matter will appear as a shadow in the captured image, degrading the quality of the captured image. End up. In a camera using a silver salt film, since the film is sent each time an image is taken, the same foreign matter does not continuously appear at the same position on the image. However, in a digital camera, there is no problem that a film frame is sent every time shooting is performed, and therefore, there is a problem in that the same foreign matter is continuously captured at the same position of a captured image.

  In order to solve such a problem, for example, Patent Document 1 proposes an image defect correction method for correcting a pixel defect of an image sensor. Further, in Patent Document 2, in order to simplify the setting of pixel defect position information, an extension of an image file shot in the dust acquisition mode is made different from that of a normal image, so that a dust information image is automatically generated on the PC side. A method for discriminating and correcting a correction target image using the information has been proposed.

JP-A-6-105241 JP 2004-242158 A

  However, Patent Document 1 requires a means for detecting and specifying the position of a pixel defect. Further, although Patent Document 2 has a mode dedicated to obtaining dust information, it is necessary to perform uniform luminance surface photographing near the minimum aperture value, and the exposure time may be long depending on the situation at the time of photographing. In this case, during the long-time shooting, the photographer is forced to keep the uniform luminance plane within the angle of view, which is inconvenient. In addition, there is a possibility that the user does not care about shooting for a long time and inadvertently stops the shooting action during exposure.

  The present invention has been made in view of the above-described problems, and reduces failures when acquiring information on foreign matter such as dust on an optical member disposed in front of an image sensor from captured image data, and further uses the image data. An object of the present invention is to provide an easy-to-use imaging apparatus and a control method thereof.

In order to achieve the above object, an image pickup apparatus according to the present invention includes an image pickup device that converts incident light into an electrical image signal and outputs the image signal, an aperture, a photometric means, a predetermined aperture value , and the image pickup device. A shutter speed calculating means for calculating the shutter speed based on the sensitivity of the light and the photometric value obtained by the photometric means, and photographing the foreign matter adhering to the surface of the optical member arranged in front of the image sensor. An instruction unit for detecting a foreign object image, an instruction unit for instructing foreign object detection, and a shutter speed calculated by the shutter speed calculation unit in response to an instruction for foreign object detection by the instruction unit is slower than a predetermined shutter speed. determination means for determining whether either said by determining means, when the shutter speed the is the calculated than the shutter speed set in advance are determined to be slow, Serial no aperture and changing the sensitivity, when the shutter speed the is the calculated than the shutter speed set in advance is determined to slow, the shutter speed the no later than the shutter speed set in advance As described above, the imaging device uses the setting device for changing at least one of the aperture value and the sensitivity, and the aperture value, the sensitivity, and the shutter speed determined by the setting device to detect foreign matter . and a control means for controlling to take an image.

  According to the present invention, it is possible to reduce failure when acquiring information about foreign matters such as dust on an optical member disposed in front of an image sensor from captured image data, and to provide an imaging device that is easier to use and a control method thereof. can do.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus having an image processing function according to an embodiment of the present invention. In the present embodiment, a digital still camera will be described as an example of the imaging device. As an imaging apparatus, the present invention can be applied to a digital video camera or the like in which lenses can be exchanged.

  As shown in FIG. 1, the imaging apparatus according to the present embodiment mainly includes a camera body 100 and an interchangeable lens type lens unit 300.

  In the lens unit 300, 310 is an imaging lens composed of a plurality of lenses, 312 is a diaphragm, and 306 is a lens mount that mechanically couples the lens unit 300 to the camera body 100. The lens mount 306 includes various functions for electrically connecting the lens unit 300 to the camera body 100. Reference numeral 320 denotes an interface for connecting the lens unit 300 to the camera body 100 in the lens mount 306, and 322 denotes a connector for electrically connecting the lens unit 300 to the camera body 100.

  The connector 322 transmits a control signal, a status signal, a data signal, and the like between the camera body 100 and the lens unit 300, and also has a function of supplying or supplying a current of various voltages. The connector 322 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  Reference numeral 340 denotes an aperture control unit that controls the aperture 312 in cooperation with a shutter control unit 40 that controls a shutter 12 of the camera body 100 described later based on photometric information from the photometry control unit 46. Reference numeral 342 denotes a focus control unit that controls focusing of the imaging lens 310, and 344 denotes a zoom control unit that controls zooming of the imaging lens 310.

  A lens system control circuit 350 controls the entire lens unit 300. The lens system control circuit 350 includes a memory for storing operation constants, variables, programs, and the like. Further, a non-volatile memory that holds identification information such as a number unique to the lens unit 300, management information, function information such as an open aperture value, a minimum aperture value, and a focal length, and current and past setting values is also provided.

  Next, the configuration of the camera body 100 will be described.

  Reference numeral 106 denotes a lens mount that mechanically couples the camera body 100 and the lens unit 300, and reference numerals 130 and 132 denote mirrors, which guide light beams incident on the imaging lens 310 to the optical viewfinder 104 by a single-lens reflex system. The mirror 130 may be either a quick return mirror or a half mirror. Reference numeral 12 denotes a shutter having a diaphragm function, and reference numeral 14 denotes an image sensor that converts an optical image into an electrical signal. The light beam incident on the imaging lens 310 is guided by the single-lens reflex system through the aperture 312 that is a light amount limiting unit, the lens mounts 306 and 106, the mirror 130, and the shutter 12, and forms an optical image on the imaging element 14.

  Reference numeral 16 denotes an A / D converter that converts an analog signal output from the image sensor 14 into a digital signal. A timing generation circuit 18 supplies a clock signal and a control signal to the image sensor 14, the A / D converter 16, and the D / A converter 26, respectively, and is controlled by the memory control circuit 22 and the system control circuit 50.

  An image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22. Further, the image processing circuit 20 performs predetermined arithmetic processing using the image data output from the A / D converter 16 as necessary. TTL (through-the-lens) type autofocus (AF) processing and automatic exposure (AE) for the system control circuit 50 to control the shutter control unit 40 and the focus adjustment unit 42 based on the obtained calculation result. Processing and flash pre-emission (EF) processing can be performed. Further, the image processing circuit 20 performs predetermined arithmetic processing using the image data output from the A / D converter 16, and also performs TTL auto white balance (AWB) processing based on the obtained arithmetic result. ing.

  In the example shown in FIG. 1 in the present embodiment, the focus adjustment unit 42 and the photometry control unit 46 are provided exclusively. Therefore, the AF adjustment process, the AE process, and the EF process are performed using the focus adjustment unit 42 and the photometry control unit 46, and the AF process, the AE process, and the EF process using the image processing circuit 20 are not performed. It does not matter. Further, AF processing, AE processing, and EF processing are performed using the focus adjustment unit 42 and the photometry control unit 46, and further, AF processing, AE processing, and EF processing using the image processing circuit 20 are performed. It is good also as a structure.

  A memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32. Image data output from the A / D converter 16 is written into the image display memory 24 or the memory 30 via the image processing circuit 20, the memory control circuit 22, or only through the memory control circuit 22.

  Reference numeral 24 denotes an image display memory, 26 denotes a D / A converter, and 28 denotes an image display unit made up of a TFT type LCD or the like. Display image data written in the image display memory 24 is stored in the D / A converter 26. Via the image display unit 28. An electronic viewfinder (EVF) function can be realized by sequentially displaying captured image data using the image display unit 28. Further, the image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50, and when the display is turned off, the power consumption of the camera body 100 can be significantly reduced. it can.

  Reference numeral 30 denotes a memory for storing captured still images, which has a storage capacity sufficient to store a predetermined number of still images. This makes it possible to write a large amount of images to the memory 30 at high speed even in continuous shooting or panoramic shooting in which a plurality of still images are continuously shot. The memory 30 can also be used as a work area for the system control circuit 50.

  A compression / decompression circuit 32 compresses / decompresses image data using a known compression method such as adaptive discrete cosine transform (ADCT). The compression / decompression circuit 32 reads an image stored in the memory 30, performs a compression process or an expansion process, and writes the processed data to the memory 30 again.

  Reference numeral 40 denotes a shutter control unit that controls the shutter 12 in cooperation with an aperture control unit 340 that controls the aperture 312 based on photometric information from the photometry control unit 46. A focus adjusting unit 42 performs AF (autofocus) processing. A light beam incident on the imaging lens 310 in the lens unit 300 is incident as a single lens reflex system through a diaphragm 312, lens mounts 306 and 106, a mirror 130, and a focus adjustment sub-mirror (not shown), thereby forming an optical image. The in-focus state of the captured image is measured.

  A photometry control unit 46 performs AE (automatic exposure) processing. A light beam incident on the imaging lens 310 in the lens unit 300 is incident as a single-lens reflex system through a diaphragm 312, lens mounts 306 and 106, a mirror 130, and a photometric sub-mirror (not shown), thereby forming an optical image. Measure the exposure of the image. A flash 48 has an AF auxiliary light projecting function and a flash light control function. The photometry control unit 46 also has an EF (flash dimming) processing function in cooperation with the flash 48.

  Further, the AF control may be performed using the measurement result by the focus adjustment unit 42 and the calculation result obtained by calculating the image data from the A / D converter 16 by the image processing circuit 20. Furthermore, exposure control may be performed using the measurement result obtained by the photometry control unit 46 and the calculation result obtained by calculating the image data from the A / D converter 16 by the image processing circuit 20.

  Reference numeral 50 denotes a system control circuit that controls the entire camera body 100, and incorporates a known CPU. A memory 52 stores constants, variables, programs, and the like for operating the system control circuit 50.

  Reference numeral 54 denotes a notification unit for notifying the outside of an operation state, a message, and the like using characters, images, sounds, and the like in accordance with execution of a program in the system control circuit 50. As the notification unit 54, for example, a display unit that performs visual display using an LCD, an LED, or the like, or a sound generation element that performs voice notification, etc., is used, and the notification unit 54 is configured by a combination of one or more of these. In particular, in the case of the display unit, it is installed at one or a plurality of locations near the operation unit 70 of the camera body 100 that are easy to see. In addition, the notification unit 54 has a part of its function installed in the optical viewfinder 104.

  Among the display contents of the notification unit 54, the following are displayed on the image display unit 28 such as an LCD. First, there are displays relating to shooting modes such as single-shot / continuous-shot shooting display, self-timer display, and the like. In addition, there are displays relating to recording such as compression rate display, recording pixel number display, recording number display, and remaining image number display. In addition, there are displays relating to photographing conditions such as shutter speed display, aperture value display, exposure correction display, dimming correction display, external flash emission amount display, and red-eye reduction display. In addition, there are a macro shooting display, a buzzer setting display, a battery remaining amount display, an error display, an information display with a multi-digit number, and a recording medium 200 and PC 210 attachment / detachment state display. Furthermore, the attachment / detachment state display of the lens unit 300, the communication I / F operation display, the date / time display, the display indicating the connection state with the external computer, and the like are also performed.

  In addition, among the display contents of the notification unit 54, examples of what is displayed in the optical finder 104 include the following. In-focus display, shooting preparation completion display, camera shake warning display, flash charge display, flash charge completion display, shutter speed display, aperture value display, exposure correction display, recording medium writing operation display, and the like.

  Reference numeral 56 denotes an electrically erasable / recordable non-volatile memory in which programs and the like to be described later are stored. For example, an EEPROM or the like is used.

  Reference numerals 60, 62, 64, 66, and 70 are operation means for inputting various operation instructions of the system control circuit 50, and include one or a plurality of switches, dials, touch panels, pointing by line-of-sight detection, voice recognition devices, and the like. Composed of a combination.

  Here, a specific description of these operating means will be given.

  Reference numeral 60 denotes a mode dial switch which can be used to switch and set each function shooting mode such as an automatic shooting mode, a program shooting mode, a shutter speed priority shooting mode, an aperture priority shooting mode, a manual shooting mode, and a depth of focus priority (depth) shooting mode. it can. In addition, each function shooting mode such as portrait shooting mode, landscape shooting mode, close-up shooting mode, sports shooting mode, night view shooting mode, panoramic shooting mode, and the like can be switched and set.

  Reference numeral 62 denotes a shutter switch SW1, which is turned on while a shutter button (not shown) is being operated (for example, half-pressed), and instructs to start operations such as AF processing, AE processing, AWB processing, and EF processing.

  A shutter switch SW2 64 is turned on when a shutter button (not shown) is completed (for example, fully pressed), and instructs the start of a series of processes including exposure processing, development processing, and recording processing. First, in the exposure process, the signal read from the image sensor 14 is written into the memory 30 via the A / D converter 16 and the memory control circuit 22, and further the calculation in the image processing circuit 20 and the memory control circuit 22 is performed. Development processing using is performed. Further, in the recording process, the image data is read from the memory 30, compressed by the compression / decompression circuit 32, and the image data is written or transmitted to the recording medium 200 or the PC 210.

  Reference numeral 66 denotes a playback switch, which instructs to start a playback operation for reading an image shot in the shooting mode state from the memory 30, the recording medium 200, or the PC 210 and displaying it on the image display unit 28.

  68 is a single-shot / continuous-shot switch. When the shutter switch SW2 (64) is pressed, a single-shot mode in which one frame is shot and the camera is in a standby state, and while the shutter switch SW2 (64) is being pressed, continuous shooting is performed. The continuous shooting mode can be set.

  An operation unit 70 includes various buttons and a touch panel. Examples include a menu button, a set button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, a menu movement + (plus) button, and a menu movement− (minus) button. Furthermore, a playback image movement + (plus) button, a playback image movement-(minus) button, a shooting image quality selection button, an exposure correction button, a light adjustment correction button, an external flash emission amount setting button, a date / time setting button, and the like are also included. The functions of the plus button and the minus button can be selected more easily with numerical values and functions by providing a rotary dial switch.

  In addition, there are playback switches that can set each function mode such as a playback mode, a multi-screen playback / erase mode, and a PC connection mode. In addition, there is an image display ON / OFF switch for setting ON / OFF of the image display unit 28, and a quick review ON / OFF switch for setting a quick review function for automatically reproducing image data taken immediately after shooting. Further, there is a compression mode switch that is a switch for selecting a compression rate for JPEG compression or for selecting a RAW mode in which a signal from an image sensor is directly digitized and recorded on a recording medium. In addition, there is an AF mode setting switch that can set a one-shot AF mode and a servo AF mode. In the one-shot AF mode, an autofocus operation is started when the shutter switch SW1 (62) is pressed, and once focused, the focused state is maintained. In the servo AF mode, the autofocus operation is continued while the shutter switch SW1 (62) is being pressed. Further, as will be described later, it includes a setting switch that can set a dust information acquisition mode for capturing dust information by capturing dust detection images.

  Reference numeral 72 denotes a power switch, which can switch and set the power-on and power-off modes of the camera body 100. Also, the power on and power off settings of various accessory devices such as the lens unit 300, the external flash 112, the recording medium 200, and the PC 210 connected to the camera body 100 can be switched.

  A power control unit 80 includes a battery detection circuit, a DC-DC converter, a switch circuit that switches a block to be energized, and the like. The power supply control unit 80 detects the presence / absence of a battery, the type of battery, and the remaining battery level, controls the DC-DC converter based on the detection result and an instruction from the system control circuit 50, and requires a necessary voltage. It is supplied to each part including the recording medium for a period.

  Reference numerals 82 and 84 denote connectors, 86 denotes a primary battery such as an alkaline battery or lithium battery, a secondary battery such as a NiCd battery, NiMH battery, Li-ion battery, or Li polymer battery, an AC adapter, or the like.

  Reference numerals 90 and 94 denote recording media such as a memory card and a hard disk, and an interface with a PC. Reference numerals 92 and 96 denote connectors for connecting the recording medium such as a memory card and a hard disk and the PC. A recording medium attachment / detachment detection circuit 98 detects whether the recording medium 200 or the PC 210 is attached to the connectors 92 and / or 96.

  Although the present embodiment has been described as having two systems of interfaces and connectors for attaching the recording medium, the interface and connectors for attaching the recording medium may have a single or a plurality of systems. . Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.

  As the interface and the connector, it is possible to configure using interfaces that comply with various storage medium standards. For example, a PCMCIA (Personal Computer Memory Card International Association) card, a CF (Compact Flash (registered trademark)) card, an SD card, or the like. When the interfaces 90 and 94 and the connectors 92 and 96 are configured using a PCMCIA card, a CF (registered trademark) card, or the like, various communication cards can be connected. Communication cards include LAN cards, modem cards, USB (Universal Serial Bus) cards, and IEEE (Institute of Electrical and Electronic Engineers) 1394 cards. In addition, there are P1284 card, SCSI (Small Computer System Interface) card, PHS, and the like. By connecting these various communication cards, image data and management information attached to the image data can be transferred to and from other computers and peripheral devices such as a printer.

  Reference numeral 104 denotes an optical viewfinder, which guides a light beam incident on the imaging lens 310 through an aperture 312, lens mounts 306 and 106, and mirrors 130 and 132 by a single-lens reflex method, and forms an optical image for display. it can. Thereby, it is possible to perform imaging using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28. Further, in the optical viewfinder 104, some functions of the notification unit 54, for example, in-focus state, camera shake warning, flash charging, shutter speed, aperture value, exposure correction, and the like are displayed.

  Reference numeral 112 denotes an external flash device mounted via the accessory shoe 110.

  Reference numeral 120 denotes an interface for connecting the camera body 100 to the lens unit 300 in the lens mount 106.

  A connector 122 electrically connects the camera body 100 to the lens unit 300. Whether or not the lens unit 300 is attached to the lens mount 106 and / or the connector 122 is detected by a lens attachment / detachment detection unit (not shown). The connector 122 transmits a control signal, a status signal, a data signal, and the like between the camera body 100 and the lens unit 300, and has a function of supplying currents of various voltages. Further, the connector 122 may be configured to transmit not only electrical communication but also optical communication, voice communication, and the like.

  Reference numeral 200 denotes a recording medium such as a memory card or a hard disk. The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, and the like, an interface 204 with the camera body 100, and a connector 206 that connects to the camera body 100.

  As the recording medium 200, a memory card such as a PCMCIA card or compact flash (registered trademark), a hard disk, or the like can be used. Of course, it may be constituted by a micro DAT, a magneto-optical disk, an optical disk such as CD-R or CD-WR, a phase change optical disk such as DVD, or the like.

  Reference numeral 210 denotes a PC, which includes a recording unit 212 composed of a magnetic disk (HD) or the like, an interface 214 with the camera body 100, and a connector 216 for connecting with the camera body 100. Examples of the interface 94 include USB and IEEE1394, but are not particularly limited.

  Next, a process for removing the influence of dust on an optical member such as a low-pass filter and a cover glass arranged in front of the imaging element in the imaging apparatus having the above configuration will be described.

  In this embodiment, first, a dust detection image for obtaining dust information is captured, dust data is extracted, and dust data is added to a normal image that is subsequently captured, so that a PC or the like can be used. A method for removing dust by performing a post-treatment process will be described. Here, the dust detection image is preferably an image obtained by photographing a luminance surface that is as uniform as possible. However, since it is desirable that the dust detection image can be easily photographed in a familiar place, strict uniformity is not required. For example, it is assumed that a blue sky or a white wall is photographed.

  FIG. 2 is a flowchart illustrating processing in the imaging apparatus when acquiring dust information according to the present embodiment.

  First, in step S201, it is determined whether the dust information acquisition mode is selected by the operation unit 70. The determination in step S201 is repeated until the dust information acquisition mode is selected. If the dust information acquisition mode is selected, the process proceeds to step S202, and it is determined whether the shutter switch SW1 (62) is turned on. If it is OFF, the process returns to step S201 and the above process is repeated.

  On the other hand, if it is ON, the aperture setting is set to a predetermined aperture value AV1 in step S203. AV1 is set to have a narrowed aperture such as F22, for example. In the present invention, the aperture value itself is not limited as in F22, and the image may be taken in a state where the aperture is most narrowed within a range that can be set in the lens unit 300 connected to the lens mount 306. The reason for narrowing down the aperture is that dust is usually attached not on the surface of the image sensor 14 but on a protective glass for protecting the image sensor 14 or an optical filter disposed on the subject side of the image sensor. This is because the imaging state varies depending on the aperture value of the lens unit 300. For this reason, if the aperture is close to the open value, the image is blurred and an appropriate dust detection image cannot be acquired. Therefore, it is preferable to shoot with the aperture reduced as much as possible.

  In step S204, the ISO sensitivity is set to a predetermined sensitivity ISO1. ISO1 is a value such as ISO400. In this case as well, the present invention does not limit the ISO sensitivity value itself, but an ISO result in which a certain exposure result can be obtained within a range where no influence of noise appears on the captured image and the aperture value set in step S203. Any sensitivity is acceptable.

  In step S205, other shooting-related parameters are set. An example of the parameters set here is shown in FIG. Note that the parameter settings performed here are parameters used at the time of shooting for dust information acquisition. When the camera exits the dust information acquisition mode and returns to the normal shooting state, it returns to the original setting value. Further, FIG. 3 is merely an example of the setting in the present embodiment, and the operation may be performed in other combinations as a matter of course.

  Next, the process proceeds to step S206, the photometry process is performed, and then the process proceeds to step S207, where the shutter speed is calculated from the photometry value detected by the photometry process, the set aperture value, and the ISO sensitivity. Then, in step S208, it is determined whether or not the calculated shutter speed is lower than the predetermined value TV1 (long time side). If the calculated shutter speed is slower than TV1, the process proceeds to step S209, where the shutter speed is clipped by TV1. On the other hand, if the calculated shutter speed is higher than the TV 1 (on the short second side), the process proceeds to step S210 as it is. Note that TV1 is a value such as 1/2 second. This is to prevent the photographer from being confused and interrupting the shooting or removing the angle of view from the uniform luminance surface if the shooting for acquiring the dust information is exposed for a long time. is there. In addition, it is not necessary to perform unnecessarily long shooting when conditions are inappropriate for shooting for dust information acquisition, for example, when the conditions are significantly under.

  Although the case where the shutter speed is clipped by the TV 1 has been described here, the shutter speed is not limited to the TV 1 and may be changed to a shutter speed faster than the TV 1. However, the shutter speed is set so that the brightness at which dust information can be acquired with sufficient accuracy is secured. Therefore, for example, the sensitivity can be increased in a range where the influence of noise is small, for example, the ISO sensitivity is changed from 400 to 800.

  In step S210, the notification unit 54 in the optical viewfinder 104 in the notification unit 54 is turned on, and display indicating the shutter speed in the dust information acquisition mode is started.

  FIG. 4 shows an example of the viewfinder display. FIG. 4A is a diagram illustrating an example of display in the finder during normal shooting, and FIG. 4B is a diagram illustrating an example of display in the finder in the dust detection information acquisition mode. As shown in FIG. 4B, only the shutter speed is displayed in the dust position information acquisition mode, and “-” is displayed for the aperture value and ISO sensitivity which are not displayed during normal shooting. Here, an example of the display form in the present embodiment has been shown. However, the display form is not particularly limited to this, and the shutter speed used in the dust information acquisition mode is displayed and can be easily different from normal shooting. Any display that can be recognized is acceptable.

  Returning to the description of the flowchart of FIG. 2, by this time, the photographer points the imaging device to a uniform luminance surface such as a white wall as much as possible and operates the shutter switch SW2 (64). Here, since the shutter speed is displayed as the display in the viewfinder, it is possible to prompt the user to capture the uniform luminance plane within the angle of view until the photographing operation for acquiring dust information is completed. In step S211, it is determined whether or not the shutter switch SW2 (64) is turned on. If it is OFF, the process returns to step S206 to repeat the photometric process, and if it is ON, the process proceeds to step S212. In step S <b> 212, a dust detection image (shooting a uniform luminance surface) is performed, and image data is captured in the memory 30. In step S213, dust information is acquired from the image data stored in the memory 30.

Here, acquisition of dust information will be described. Specifically, the position (coordinates) and size of the dust region are obtained from the photographed dust detection image. First, the captured dust detection image area is divided into a plurality of blocks, the maximum luminance Lmax and the average luminance Lave in the block are calculated, and the threshold value T1 in the block is calculated using the following equations.
T1 = Lave × 0.6 + Lmax × 0.4

  Next, pixels that do not exceed the threshold value T1 are defined as dust pixels, and isolated regions constituted by dust pixels are each defined as one dust region di (i = 0, 1,..., N).

FIG. 8 is a diagram showing an outline of dust region size calculation. As shown in FIG. 8, for each dust region, the maximum value Xmax and the minimum value Xmin of the horizontal coordinate of the pixels constituting the dust region, the maximum value Ymax and the minimum value Ymin of the vertical coordinate are obtained, and the dust region di is obtained. The radius ri representing the size of is calculated by the following equation.
ri = [√ {(Xmax−Xmin) ² + (Ymax−Ymin) ² }] / 2

Further, the central coordinates (Xdi, Ydi) at this time are approximately Xdi = (Xmax + Xmin) / 2.
Ydi = (Ymax + Ymin) / 2
Sought in The position (coordinates) and radius determined in this way are recorded as a dust information profile.
This dust information profile has a structure as shown in FIG. As shown in FIG. 9, the dust information profile stores lens information and dust position and size information when the dust detection image is captured. More specifically, the actual aperture value (F value) at the time of detection image shooting and the lens pupil position at that time are stored as lens information at the time of detection image shooting. Subsequently, the number of detected dust areas (integer value) is stored in the storage area, and subsequently, individual specific dust area parameters are repeatedly stored by the number of dust areas. The parameter of the dust area is a set of three numerical values: a dust radius (for example, 2 bytes), a center x coordinate (for example, 2 bytes) in the effective image area, and a similar y coordinate (for example, 2 bytes).

  In the present embodiment, as the dust information, the position and size of the detected dust are converted into data and described in the main image file. However, the present invention is not limited to this. For example, bitmap data indicating a dust area for the entire image may be recorded as it is. Alternatively, a dust information file obtained by filing the dust information profile may be created separately, and the main image file may have only link information for the dust information file. Therefore, there is no particular limitation on the data format of the dust information. In addition, as a method for detecting dust, it is sufficient to use that the amount of light incident on the pixel corresponding to the dust attachment position decreases when dust adheres to the image sensor 14. For example, by comparing individual pixel data with a preset luminance value, it is possible to detect a pixel in which the amount of incident light is reduced. If it is not possible to capture a uniform luminance surface, the determination may be made using not only the luminance threshold value but also a difference with the neighboring pixel output. The dust detection method described above is merely an example, and the present invention is not particularly limited with respect to the method for detecting dust.

  The acquired dust information is stored in the nonvolatile memory 56 in step S214, and the process for acquiring dust information is terminated. Here, the dust information is stored in the non-volatile memory 56 in normal shooting performed after the dust information is acquired until the next dust information is acquired, and the dust information is continuously added to the obtained image data. Because. Therefore, in the case of adopting a configuration in which the photographer is requested to acquire dust information every time the power is turned on, the non-volatile memory may not be used.

  In addition, since the shooting operation in the dust information acquisition mode is intended to acquire dust information, in this embodiment, the shot image itself is not compressed and recorded on the recording medium 200. This is to prevent unnecessary consumption of the capacity in the recording medium 200 with image data unnecessary for the photographer, but it may be stored in the recording medium 200 after compression, as in the case of normal images. In addition, you may make some changes such as changing the extension.

  Next, dust removal processing during normal shooting using dust information stored in the nonvolatile memory 56 as described above will be described with reference to the flowcharts of FIGS.

  FIG. 5 shows image shooting processing during normal shooting in the present embodiment. In step S501, the operation state is determined until the shutter switch SW1 (62) is turned on. When turned on, the process proceeds to step S502 to perform photometry and focus adjustment processing, and then in step S503, it is determined whether or not the shutter switch SW2 (64) is turned on. If it is OFF, the process returns to step S501 and the above processing is repeated. If it is detected that the switch is turned ON, the process proceeds to step S504 to perform shooting. When the photographing is finished, the process proceeds to step S505, and it is determined whether or not valid dust information exists in the nonvolatile memory 56. If dust information exists, the process proceeds to step S506, and if not, the process proceeds to step S507 to store the captured image data in the recording medium 200.

  In the present embodiment, it is determined whether or not dust information exists in the nonvolatile memory 56, but it is originally a necessary condition whether or not shooting is performed in the dust information acquisition mode described above. The determination method is not particularly limited. For example, a method may be used in which a certain flag is set at the time of shooting in the dust information acquisition mode and the flag is evaluated.

  In step S506, the acquired dust information is embedded in the header area such as the maker note portion for the photographed image data, and the image data in which the dust information is embedded in the recording medium 200 is stored in step S507. At this time, when the PC 210 is connected to the end of the interface 94 by USB or the like, the image data in which the dust information is embedded is directly transferred to the recording unit (HD) in the PC 210 and stored. Also good.

  Next, the operation on the PC 210 side which is an image processing apparatus will be described with reference to FIG. In step S601, it is determined whether dust information is embedded in the selected image. If it is embedded, the process advances to step S602 to capture dust information. In step S603, correction processing such as pixel complementation processing using peripheral pixels of dust is performed in order to remove the influence of dust in the image data from the captured dust information. The details of the pixel complementing process performed as the correction process are not particularly limited, and a general defective pixel complementing process may be applied. Thereafter, the process proceeds to step S604, and an image after correction processing in which the influence of dust is removed from the photographed image is newly recorded.

  In the present embodiment, the camera main body 100 records dust information embedded in captured image data, and performs a correction process for removing the influence of dust in the image processing on the PC 210 side. In contrast, when an image is captured and recorded by the camera body 100, correction processing is performed to remove the influence of dust without embedding dust information, and the image after correction processing is recorded on the recording medium 200. Also good.

  As described above, according to the present embodiment, the dust information acquisition image that is easy to detect dust can be easily photographed, and the optimum for removing the influence of dust from the captured image data by correction processing. Trash information can be acquired. Further, in the dust information acquisition mode, display in the viewfinder different from normal shooting is performed, and at least information related to the shutter speed is displayed, so that a photographer's operation mistake can be prevented.

<Modification>
Next, a modification of the above-described embodiment will be described with reference to the flowchart of FIG. The process shown in the flowchart of FIG. 7 is different from the flowchart of FIG. 2 in that the process of step S701 is added. Since other processes are the same as those in FIG. 2, the same step numbers are given, and step S <b> 701 will be described below.

  In step S206, photometric processing is performed, and after the shutter speed is calculated in step S207, the calculated shutter speed is compared with the predetermined value TV1 in step S208. If the calculated shutter speed is slower than TV1, the process proceeds to step S209, and the shutter speed is clipped by TV1. Thereafter, the process proceeds to step S701, and the set aperture value AV1 is changed in a direction in which the aperture is further opened so that an appropriate exposure amount is obtained. Note that the range that can be changed here is between AV1 and AV2, and AV2 is a range that can secure an imaging state in which dust information can be acquired from the captured image within a predetermined accuracy, and is as open as possible. Suppose that Processing other than the above is the same as the processing described with reference to FIG.

  As described above, according to the modification of the present embodiment, it is possible to further prevent an image captured for dust detection from becoming an under image inappropriate for dust detection.

It is a block diagram which shows the structure of the imaging device in embodiment of this invention. It is a flowchart which shows the process at the time of the dust information acquisition in embodiment of this invention. It is a figure which shows the setting parameter list at the time of the dust information acquisition in embodiment of this invention. It is a figure which shows an example of the display in a finder in embodiment of this invention. It is a flowchart which shows the image imaging process in embodiment of this invention. It is a flowchart which shows the procedure of the correction process in embodiment of this invention. It is a flowchart which shows the process at the time of the dust information acquisition in the modification of embodiment of this invention. It is a figure which shows the outline | summary of dust area size calculation in embodiment of this invention. It is a figure which shows an example of the structure of the dust information profile in embodiment of this invention.

Explanation of symbols

12: Shutter, 14: Image sensor, 16: A / D converter, 18: Timing generation circuit, 20: Image processing circuit, 22: Memory control circuit, 24: Image display memory, 26: D / A converter, 28 : Image display unit, 30: Memory, 32: Compression / decompression circuit, 40: Shutter control unit, 42: Focus adjustment unit, 46: Photometry control unit, 48: Flash, 50: System control circuit, 52: Memory, 54: Notification unit, 56: Non-volatile memory, 60: Mode dial switch, 62: Shutter switch SW1, 64: Shutter switch SW2, 66: Playback switch, 68: Single / continuous shooting switch, 70: Operation unit, 80: Power control Part, 82, 84: connector, 86: power supply, 90, 94: I / F, 92, 96: connector, 98: recording medium attachment / detachment detection part, 100: imaging device, 11 : I / F, 112: External flash, 200: Recording medium, 210: PC, 202, 212: Recording unit, 204, 214: I / F, 206, 216: Connector, 300: Lens unit, 310: Imaging lens, 312: Aperture, 306: Lens mount, 320: I / F, 322: Connector, 340: Aperture control unit, 342: Focus control unit, 344: Zoom control unit, 350: Lens system control circuit

Claims (7)

An imaging device that converts incident light into an electrical image signal and outputs the electrical signal;
Aperture,
Photometric means;
Shutter speed calculation means for calculating a shutter speed based on a predetermined aperture value , sensitivity of the image sensor, and photometric value obtained by the photometry means;
An instruction means for instructing foreign object detection to detect an image of the foreign object by photographing the foreign object attached to the surface of the optical member disposed in front of the image sensor;
Determining means for determining whether the shutter speed calculated by the shutter speed calculating means is slower than a predetermined shutter speed in response to an instruction for foreign object detection by the instruction means ;
When the determination means determines that the calculated shutter speed is not slower than the predetermined shutter speed, the aperture value and the sensitivity are not changed and the predetermined shutter speed is used. Also, when it is determined that the calculated shutter speed is slow, setting means for changing at least one of the aperture value and the sensitivity so that the shutter speed is not slower than the predetermined shutter speed. When,
The was determined by the setting means aperture value, the sensitivity, and by using the shutter speed, imaging apparatus characterized by a control means for controlling to take an image of foreign object detected by the image sensor. Said predetermined aperture value, the imaging device may be set, the imaging apparatus according to claim 1, characterized in that said aperture is a value which most aperture Ri written. By defining the amplification factor of the output of the image sensor, further comprising a sensitivity setting means for setting the sensitivity,
The shutter speed calculating unit, when the foreign object detection is instructed from the instruction means, according to claim 1, with a predetermined sensitivity set by the sensitivity setting means and calculates the shutter speed Or the imaging device of 2. A foreign substance information detection means for detecting the foreign substance information on the basis of the image of the foreign object detection acquired by the control of said control means,
4. The apparatus according to claim 1, further comprising an adding unit that adds the foreign substance information or link information to the foreign substance information to an image file obtained by processing an image signal output from the image sensor. The imaging apparatus of Claim 1 . A foreign substance information detection means for detecting the foreign substance information on the basis of the image of the foreign object detection acquired by the control of said control means,
The imaging apparatus according to any one of claims 1 to 3, further comprising a correction means for correcting, based an image signal output from the imaging element to the foreign substance information. It further has a display means,
When taking an image for the foreign object detection, different from the case of photographing an image other than the image for the foreign object detection, claims 1 to 5, characterized in that the display includes at least shutter speed on the display means The imaging device according to any one of the above. When it is determined that the shutter speed calculated by the shutter speed calculation unit is slower than the preset shutter speed, the setting unit can detect the foreign matter information within a predetermined accuracy with respect to the aperture value. The imaging apparatus according to claim 4, wherein the imaging apparatus is changed within a range in which a satisfactory imaging state can be secured .

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