JP2005321602A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an imaging apparatus in which the state of vignetting which occurs when auxiliary light is used before photographing is confirmed by a display device and photographing that matches the intended photographing image of a user can be performed. <P>SOLUTION: The imaging apparatus includes an imaging device for photoelectrically converting light from a subject, an imaging optical system, an auxiliary light means for projecting auxiliary light to the subject, and the display device for displaying an image. The imaging apparatus is provided with a vignetting estimating means for estimating the occurrence of vignetting of auxiliary light caused by part of the imaging optical system. Based upon the result of the estimation by the black-frame estimating means, the imaging apparatus displays the state of vignetting onto the display device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus having an imaging element, auxiliary light means, and a display device for displaying an image.

  2. Description of the Related Art Conventionally, an imaging apparatus represented by a camera is provided with auxiliary light means such as an electric flash to facilitate shooting in a dark place.

  On the other hand, in shooting using an auxiliary light means such as a flash, depending on the shooting conditions, the auxiliary light beam is blocked by a lens barrel or the like that includes an imaging optical system protruding from the imaging apparatus body, and so-called vignetting occurs. It is known. It is known that the occurrence of this vignetting becomes more conspicuous in short-distance shooting especially when a wide-angle lens is used.

  Various proposals have been made for the problem of vignetting during flash photography.

  To solve this vignetting problem, the flash is housed along the peripheral edge of the main body casing and rotated along a plane substantially perpendicular to the optical axis of the imaging optical system in order to reduce the size of the image pickup device and reduce vignetting. Thus, there is disclosed one that extends from the housing (for example, see Patent Document 1).

Also, a camera that prohibits light emission is disclosed when vignetting is determined from the lens data obtained from the attached photographic lens and the camera built-in flash data that has been written in advance. (For example, refer to Patent Document 2).
JP 2003-330071 A JP 2001-13559 A

  In recent years, instead of using a camera that uses film, an image sensor that photoelectrically converts subject light is used, and the output from the image sensor is processed into image data, which is then stored in a storage medium. A so-called digital camera having a display device for displaying the obtained image is generally used.

  These digital cameras are rapidly becoming smaller and can perform close-up photography that is incomparable to conventional cameras using film. Furthermore, when the imaging optical system used is a zoom lens, a lens configuration that has a long overall length from a wide angle is adopted, and these are combined to make the above-described vignetting problem more likely to occur. Yes.

  On the other hand, the imaging apparatus described in Patent Document 1 requires a mechanism for rotating the flash light emitting unit on the camera body side, which is not desirable for downsizing. Further, the camera described in Patent Document 2 prohibits flash emission, thereby causing problems such as camera shake as well as a decrease in color reproduction.

  On the other hand, in a digital camera, the captured image can be reproduced on the display device and immediately confirmed, so that even if a little vignetting occurs, if the necessary subject part is not vignetted, it is used by trimming after shooting The method is also possible, and there are cases in which color reproduction degradation and camera shake are more problematic than slight vignetting.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to obtain an imaging device capable of confirming the occurrence state of vignetting on a display device when auxiliary light is used before photographing, and capable of photographing according to a user's photographed image. To do.

  The above problem is solved by the following configuration.

  1) Imaging having an imaging device that photoelectrically converts subject light, an imaging optical system that guides the subject light to the imaging device, auxiliary light means that projects auxiliary light onto the subject, and a display device that displays an image The apparatus has vignetting prediction means for predicting occurrence of vignetting of the auxiliary light by a part of the imaging optical system, and displays the vignetting state on the display device based on a prediction result of the vignetting prediction means. An imaging apparatus characterized by performing.

  2) The image capturing apparatus according to 1), wherein the vignetting prediction unit predicts vignetting based on a subject distance near a position where vignetting occurs on a shooting screen.

  3) The imaging device according to 1) or 2), wherein the display of the vignetting state is displayed by being superimposed on a preview image.

  4) The imaging apparatus includes a storage unit that records captured image data, and a release unit that can discriminate between a half-pressed state and a fully-pressed state. When the release unit is half-pressed, the vignetting state The imaging apparatus according to any one of 1) to 3), wherein the image is displayed and the image is obtained when the release unit is fully pressed, and the image data obtained by the imaging using the auxiliary light unit is stored in the storage unit.

  That is, the present inventor pays attention to the characteristics unique to an imaging device capable of displaying an image obtained by the imaging device in real time before photographing, and displays an expected vignetting occurrence state on the display device when using auxiliary light. By doing so, the user can continue to shoot as it is, or the setting can be changed so that vignetting does not occur, and it was found that it was possible to shoot according to the shooting image of the user It is an invention.

  According to the invention of 1) above, by displaying the vignetting state on the display device based on the prediction result by the vignetting prediction means, it becomes possible to confirm the vignetting occurrence state in advance before photographing. Therefore, depending on the user's judgment, if it is possible to handle by trimming etc., the shooting can be continued as it is, or the zoom position and the subject distance in the peripheral part are changed so that the same shooting magnification is obtained so that vignetting does not occur. After setting, it becomes possible to take a picture, and it is possible to obtain an imaging apparatus capable of taking pictures according to a user's photographed image.

  According to the above 2), it is possible to more accurately predict the state of vignetting.

  According to the above 3), the photographing result can be predicted, and the user can easily determine whether to continue the photographing as it is or to reset the setting so that no vignetting occurs.

  According to the above 4), it is possible to check the occurrence state of vignetting on the display device before photographing, and it is possible to obtain an imaging device capable of photographing according to the photographed image of the user.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is a diagram illustrating an appearance of a digital camera which is an example of an imaging apparatus according to the present invention. 1A is a perspective view of the front side of the camera, and FIG. 1B is a perspective view of the back side of the camera.

  In FIG. 1A, 81 is a zoom imaging optical system, 82 is a finder window, 83 is a release button, 84 is a flash light emitting unit, 86 is a light control sensor window, 87 is a strap attaching unit, and 88 is an external input / output terminal. (For example, a USB terminal). A lens cover 89 is retracted when the zoom imaging optical system 81 is not used.

  The release button 83 is pushed in one step (hereinafter referred to as switch S1 ON) to perform a camera shooting preparation operation, that is, a focusing operation and a photometric operation. The two-step push-in (hereinafter referred to as switch S2 ON) The exposure operation is performed.

  In FIG. 1B, 91 is a viewfinder eyepiece, 92 is a red and green display lamp, and displays AF and AE information to the photographer by lighting or blinking. A zoom button 93 is a button for zooming up and down. Reference numeral 95 denotes a menu / set button, reference numeral 96 denotes a selection button, which is a four-way switch, and reference numeral 100 denotes an image display unit that displays an image, other character information, and the like. The menu / set button 95 has a function of displaying various menus on the image display unit 100, selecting with the selection button 96, and confirming with the menu / set button 95. Reference numeral 97 denotes a reproduction button, which is a button for reproducing a photographed image. A display button 98 is a button for selecting display or deletion of an image displayed on the image display unit 100 and other character information. An erasure button 99 is a button for erasing the recorded image. 101 is a tripod hole, and 102 is a battery / card cover. The battery / card cover 102 has a battery for supplying power to the camera, and a card slot for recording captured images. A card-type recording memory for recording images can be inserted and removed. It has become.

  FIG. 2 is a schematic block diagram showing the internal configuration of the digital camera shown in FIG. The internal configuration will be described with reference to FIG. In the present invention, a CCD (Charge Coupled Device) type image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor, or the like can be applied as an image pickup element. In this example, a CCD type image sensor is used as the image pickup element. This will be explained using

  In the figure, reference numeral 40 denotes a CPU for controlling each circuit. The zoom imaging optical system 81 includes a lens unit 1, an aperture shutter unit 2, an optical filter 3 in which an infrared light cut filter and an optical low-pass filter are stacked, a first motor 4, a second motor 5, and an aperture shutter actuator. .

  More specifically, the lens unit 1 is configured as a lens system having a plurality of lenses, and the position of the plurality of lenses on the optical axis is moved by driving the first motor 4 so that zooming is performed. It has become. Among these lenses, a lens used for focusing is driven by the second motor 5 to perform focus adjustment. Further, the aperture shutter unit is opened and closed by the aperture shutter actuator 6 to adjust the exposure amount. The first motor 4, the second motor 5, and the aperture shutter actuator 6 are respectively connected via a first motor drive circuit 7, a second motor drive circuit 8, and an aperture shutter drive circuit 9 controlled by control signals from the CPU 40. Driven.

  The timing generator 10 generates a drive control signal for the CCD 12 based on a clock sent from the timing control circuit 11. For example, a timing signal for starting and ending charge accumulation in the CCD 12 and a readout control signal for the charge accumulation amount of each pixel. A clock signal such as (horizontal synchronization signal, vertical synchronization signal, transfer signal) is generated and output to the CCD 12. The imaging circuit 13 photoelectrically converts subject light by the CCD 12 and, for example, in the case of a CCD using a primary color filter, it outputs image analog signals of each color component of R (red), G (green), and B (blue). Output to the processing unit 14.

  The signal processing unit 14 performs signal processing on the analog image signal output from the imaging circuit 13. The signal processing unit 14 performs noise reduction and gain adjustment of the image analog signal by correlated double sampling (CDS) and auto gain control (AGC), and outputs the result to the image processing unit 15.

  The image processing unit 15 performs A / D conversion on the input image analog signal based on the A / D conversion clock from the timing control circuit 11 and converts it into a digital signal (hereinafter referred to as pixel data). Next, after black level correction of pixel data is performed, white balance (WB) is adjusted. The white balance is adjusted by a conversion coefficient input from the CPU 40. This conversion coefficient is set for each captured image. Further, after performing γ correction, the pixel data is output to the image memory 16. The image memory 16 is a memory that stores pixel data output from the image processing unit 15.

  The VRAM 17 is a buffer memory for images displayed on the image display unit 100, and has a storage capacity that is at least equal to or greater than the integrated value of the number of pixels of the image display unit 100 and the number of bits necessary for display. For the image display unit 100, for example, a display device such as an LCD or an organic EL is used. A D / A conversion unit that D / A converts pixel data is provided between the VRAM 17 and the image display unit 100 according to the display device used.

  Thereby, at the time of framing at the time of shooting, the pixel data captured at a predetermined time interval is stored in the image memory 16 and transferred to the VRAM 17 after predetermined signal processing by the CPU 40 and displayed on the image display unit 100. A subject image can be confirmed and used as a viewfinder (referred to as a through image display or a preview image display).

  The captured image recorded in the removable image recording memory card 50 is transferred to the CPU 40 via an interface corresponding to the card in the CPU, and is transferred to the VRAM 17 after predetermined signal processing by the CPU 40. Display is performed on the display unit 100, and reproduction is possible.

  The interface 32 transmits and receives signals to and from an external personal computer or printer. The interface 32 is sent to an external personal computer or printer via an external input / output terminal (for example, USB terminal) 88, or external personal computer or printer. Or receive more data.

  The flash control circuit 21 is a circuit that controls the light emission of the flash light emitting unit 84. The flash control circuit 21 is controlled by the CPU 40 to control the presence / absence of flash light emission, the light emission timing, the charging of the light emission capacitor, and the like, and the light emission input from the light control circuit 24 connected to the light control sensor 23. The light emission is stopped based on the stop signal.

  The clock circuit 25 manages the date and time when the image was taken. The clock circuit 25 may operate by receiving power supply from a power supply circuit 27 that supplies power to each unit, but it is desirable to operate with a separate power source (not shown). .

  The power supply circuit 27 supplies power to the CPU 40 and each unit. The power supply circuit 27 is supplied with power from the A / C adapter 29 via the battery 26 or the DC input terminal 28.

  The operation SW 30 is a switch group that is turned ON / OFF by various operation buttons such as the release button 83, the zoom button 93, the menu / set button 95, etc. shown in FIG. The ON / OF signal of the operation SW group 30 is sent to the CPU 40, and the CPU 40 controls the operation of each unit according to the operation SW that is turned on.

  The EEPROM 31 is a non-volatile memory, and is used for storing different characteristic values for each camera. The individually different characteristic values are, for example, information on the infinite position of the focusing lens at each focal length of the zoom imaging optical system 81, and are written in the manufacturing process. The CPU 40 reads out the characteristic values that are different for each camera from the EEPROM 31 as necessary, and uses them for controlling each part.

  The CPU 40 performs not only data exchange and timing control of each unit, but also various other functions based on software stored in the ROM 20. For example, the aperture value and shutter speed exposure conditions at the time of shooting based on the pixel data obtained in the image memory 16 (AE function), the focusing lens is moved little by little, and the image data is obtained from the obtained pixel data. Generated and evaluated based on this image data, determination of optimum focusing lens position (AF function), function to generate and compress image data from pixel data for recording on memory card 50, recorded on memory card 50 In order to display the captured image on the image display unit 100, the image data recorded on the memory card 50 is read and decompressed.

  The above is the internal block configuration of the digital camera which is an example of the imaging apparatus according to the present invention.

  The digital camera as an example of the imaging apparatus of the present invention has a shooting mode for shooting still images and / or moving images, a playback mode for playing back and deleting the shot images, and a setup mode for setting each function of the camera. ing. The present invention relates to the shooting mode, and the shooting mode will be described in detail below.

  FIG. 3 is a flowchart showing a schematic operation in the shooting mode of the digital camera which is an example of the imaging apparatus according to the present invention. The following operations are performed by the CPU 40 controlling each unit based on software and constants stored in the ROM 20 and the EEPROM 31 shown in FIG. Hereinafter, description will be given with reference to FIG.

  In the figure, it is first determined whether or not the main switch is turned on (step S101). If the main switch is ON (step S101; Yes), a preview image is displayed (step S102). As described above, the preview image display is displayed on the image display unit 100 (see FIG. 2).

  Thereafter, it waits for the switch S1 to be turned on (step S103). If the switch S1 is not turned on (step S103; No), a loop of S101 to S103 is entered, and the preview image display is continued unless the main switch is turned off in step S101.

  When the switch S1 is turned on (step S103; Yes), the AE / AF function operation is performed (step S104). In the AE / AF function operation, as described above, the aperture value at the time of shooting, the shutter speed, and whether or not the flash emission is necessary are determined, the focusing lens is moved little by little, and the pixel data obtained from each is used. Image data is generated, and evaluation is performed based on the image data to determine an optimum focusing lens position.

  FIG. 4 shows a focus evaluation area for evaluating subject image data during the AF function operation of the camera of the present invention. This figure shows a case where a flash light emitting unit 84 as an auxiliary light unit is disposed obliquely upward to the right with respect to the imaging optical system 81 when viewed from the front of the camera.

  As shown in FIG. 4, when the flash light emitting unit 84 is arranged obliquely on the right side with respect to the imaging optical system 81 when viewed from the front of the camera, the area indicated by A around the optical axis on the subject side, and the flash emission The subject image data is evaluated for the area indicated by B in the peripheral portion where the vignetting on the diagonal side of the imaging optical system 81 may occur with respect to the position of the portion, and the respective best focusing lens positions are determined. To do. As a result, the subject distances in the areas of the central part A and the peripheral part B can be known.

  The best focusing lens position in the central area A is used as a stop position of the focusing lens at the time of shooting, and the best focusing lens position in the peripheral area B is converted into a subject distance, and is shown in FIG. Used in the flow.

  Returning to FIG. 3, after the operation of the AE / AF function is completed, it is determined whether or not flash photography is performed (step S105). This determination is made from the result of the AE function operation and the flash mode setting performed in step S104. When flash emission as auxiliary light is necessary (step S105; Yes), the subject distance in the peripheral portion and the zoom position of the photographing lens are compared with a table prepared in advance to determine whether or not it is within the vignetting occurrence region ( Step S106).

  FIG. 5 is an example of a graph based on a table prepared in advance for determining whether the area is in the vignetting occurrence area. The figure shows a region K where vignetting occurs and a region N where vignetting does not occur, with the horizontal axis as the subject distance and the vertical axis as the zoom position of the imaging optical system. For example, the table is stored in the EEPROM 31 (see FIG. 2) of the camera. Has been. This table may be created based on geometric drawing from the camera layout, or may be created based on actually captured data. Based on this table, it is predicted whether or not vignetting will occur before shooting. In the figure, W represents the wide end, T represents the tele end, and M1 to M5 represent intermediate focal lengths.

  In the graph shown in FIG. 5, that is, the table, for example, when the zoom position of the imaging optical system is M2 and the subject distance of the peripheral portion B is 0.09 m, the vignetting occurs because the area is K. Predict. Further, when the zoom position of the imaging optical system is M4 and the subject distance of the peripheral portion B is 0.125 m, it is predicted that no vignetting occurs because it is in the N region. In other words, this table corresponds to vignetting prediction means, and predicts whether or not vignetting has occurred.

  Returning to FIG. 3, when it is determined in step S106 that the combination of the zoom position of the imaging optical system and the subject distance of the peripheral portion B is within the vignetting occurrence region by the above-described table as vignetting prediction means (step S106; Yes). The CPU 40 (see FIG. 2) displays the vignetting warning superimposed on the preview image (step S107).

  FIG. 6 is a diagram illustrating an example of a vignetting warning displayed to be superimposed on the preview image. (A) shows a preview image, (b) shows an image of a vignetting portion stored in the EEPROM 31 or the like in advance, and (c) shows an image of the vignetting portion superimposed on the preview image. A display image is shown.

  As shown in the figure, since the preview image does not use auxiliary light, it becomes an image with no vignetting as shown in FIG. In this image, the pre-stored image of the vignetting part shown in FIG. 5B is inserted and combined, and a photographed image after using auxiliary light as shown in FIG. Display on an image display device and warn the user of occurrence of vignetting. The amount of vignetting in this display is preferably configured to change depending on the combination of the zoom position and the subject distance, and can be a display image that approximates a captured image after using auxiliary light.

  At this time, as the preview image to be used, it is more preferable to use a preview image captured after the AF operation is completed.

  In addition, the shape of the vignetting portion stored in the EEPROM or the like shown in FIG. 4B is of course appropriately changed according to the camera layout of the flash light emitting unit 84 and the imaging optical system 81. May be created based on geometric drawing from the camera layout, or may be created based on actually captured data.

  Returning to FIG. 3, in step S107, the CPU 40 displays the vignetting warning superimposed on the preview image, and then determines whether the switch S1 is turned on again (step S108). When the switch S1 is OFF (Step S108; No), the vignetting warning displayed on the preview image and the exposure condition accumulated by the AE / AF operation and the data of the best focusing lens position are cleared. Return to step S103.

  When the switch S1 is continuously turned on (step S108; Yes), it waits for the switch S2 to be turned on (step S109). When the switch S2 is turned on (step S109; Yes), photographing processing is performed (step S110). This photographing process is performed with the focus lens position and exposure conditions determined in step S104, and a photographed image is captured. Thereafter, image processing is performed on the captured pixel data (step S111), and the image data is stored in a memory card as a recording memory (step S112). Thus, the shooting of one image is completed, and the process returns to step S101.

  If it is determined in step S105 that the flash light, which is auxiliary light, is not required (step S105; No), the operations in steps S106 and S107 are not performed, and the process proceeds to step S108. The operation of S112 is performed.

  On the other hand, when the main switch is turned off in step S101 (step S101; No), for example, an end operation (step S120) of each part such as the retracting of the photographing optical system is performed, and then the process ends.

  As described above, it has vignetting prediction means for predicting the occurrence of vignetting of auxiliary light, and displays the state of vignetting on the display device based on the prediction result by the vignetting prediction means. It becomes possible to confirm the occurrence state of vignetting. Therefore, depending on the user's judgment, if it is possible to handle by trimming etc., the shooting can be continued as it is, or the zoom position and the subject distance in the peripheral part are changed so that the same shooting magnification is obtained so that vignetting does not occur. After setting, it becomes possible to take a picture, and it is possible to obtain an imaging apparatus capable of taking pictures according to a user's photographed image.

  Further, by measuring the subject distance near the position where the vignetting occurs on the shooting screen and predicting the vignetting based on the subject distance, it is possible to more accurately predict the vignetting state.

  Furthermore, the display of the vignetting state is superimposed on the preview image, so that the shooting result can be predicted, and the user can easily determine whether to continue shooting or re-set so that no vignetting will occur. It can be.

  In the above description, the flash light emitting unit 84 that is an auxiliary light unit with respect to the imaging optical system 81 as viewed from the front of the camera has been described as being disposed diagonally to the right. When the flash light emitting unit 84 is disposed immediately above the imaging optical system 81, a region around the optical axis on the subject side and a lower region sandwiching the imaging optical system 81 with respect to the position of the flash light emitting unit The position of each of the best focusing lenses may be determined using the region of the peripheral portion. That is, it is appropriately determined according to the layout of the flash light emitting unit 84 and the imaging optical system 81.

  Further, the occurrence of vignetting is predicted using a table prepared in advance, but the present invention is not limited to this, and it is needless to say that the prediction may be performed by calculation or the like.

1 is a diagram illustrating an appearance of a digital camera that is an example of an imaging apparatus according to the present invention. It is a schematic block diagram which shows the internal structure of the digital camera shown in FIG. 3 is a flowchart showing a schematic operation in a shooting mode of a digital camera which is an example of an imaging apparatus according to the present invention. 3 shows a focus evaluation area for evaluating subject image data when the AF function of the camera of the present invention is operated. It is an example of the graph which is the origin of the table prepared beforehand for determining whether it is in a vignetting occurrence area. It is a figure which shows an example of the vignetting warning displayed superimposed on a preview image.

Explanation of symbols

31 EEPROM
40 CPU
50 Memory Card 81 Imaging Optical System 84 Flash Light Emitting Unit 83 Release Button 100 Image Display Unit

Claims (4)

An imaging apparatus comprising: an imaging device that photoelectrically converts subject light; an imaging optical system that guides the subject light to the imaging device; auxiliary light means that projects auxiliary light onto the subject; and a display device that displays an image. ,
Vignetting prediction means for predicting the occurrence of vignetting of the auxiliary light by a part of the imaging optical system;
An image pickup apparatus that displays the state of vignetting on the display device based on a prediction result of the vignetting prediction means. The imaging apparatus according to claim 1, wherein the vignetting prediction unit predicts vignetting based on a subject distance near a position where vignetting occurs on a shooting screen. The imaging apparatus according to claim 1, wherein the display of the vignetting state is displayed by being superimposed on a preview image. The imaging device includes a storage unit that records captured image data, and a release unit that can distinguish between a half-pressed state and a fully-pressed state,
In the half-pressed state of the release means, the vignetting state is displayed,
4. The apparatus according to claim 1, wherein shooting is performed with the release unit fully pressed, and image data obtained by shooting using the auxiliary light unit is stored in the storage unit. The imaging device described.

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