JP2005265941A - Photographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographic device with which a photograph in focus is taken even if there is irregularity in a lens itself and there is a mounting play of the lens, and an image surface distortion amount measuring method with which an image surface distortion amount by the irregularity of the lens itself and the mounting play in the photographic device is measured by using the photographic device. <P>SOLUTION: The photographic device is constituted so that a flat plate is previously measured, the distortion amount P11 corresponding to the irregularity is measured, a value obtained by subtracting the number a11 of best focus pulses from the distortion amount p11 corresponding to the irregularity is stored in a focus displacement storage part in the photographic device and focus compensation is performed based on displacement amount of each area stored in the focus displacement storage part in the case of photography. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to imaging apparatus for generating image data representing the image of the subject in the image sensor by forming a subject image on the imaging device in the imaging lens.

  Many cameras are equipped with ranging devices that measure the subject distance. Among such distance measuring devices, there are those that measure the subject distance regardless of the photographing optical system, and those that measure the subject distance using the subject light guided through the photographing lens in the photographing optical system. . When measuring the subject distance by the latter ones, to measure the subject distance at the center of the field angle of the object captured by the imaging lens is a majority. However, there is a case where the subject is not located at the center of the angle of view. In this case, the subject distance may not be measured and the focus may be infinite. Therefore, larger camera is raising the detection accuracy of detecting the conducted focus the position of the focus point by dividing the inside angle into a plurality of areas for each area (for example, see Patent Document 1).

  In Patent Document 1, after calculating an AF (Auto Focus) evaluation value that determines the accuracy of a subject distance at the center of the subject, AF evaluation values are also calculated on both sides of the measured center of the subject, and those AFs are calculated. Techniques have been proposed for detecting which subject on the center or both sides is at the in-focus position from the evaluation value.

However, the distance measuring device may be provided regardless of the photographing optical system. However, in the case of the distance measuring device that measures the subject distance using the subject light guided through the photographing lens, the lens itself In some cases, the image plane may be distorted due to unevenness or shakiness during assembly, resulting in an error in the AF evaluation value. This error is due to the unevenness of the lens itself and the attachment of the lens during assembly. If this error occurs, the focus position can be shifted even if the focus position is detected by the above technique. High nature. Pictures of defocus from being captured by the imaging device thus deviation of the focus position can occur.
JP-A-9-197252

  SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a photographing device for photographing a photograph that is in focus even if the lens itself is uneven or the lens is attached, and the photographing device is used for photographing the same. providing an image plane strain amount measuring method of measuring the image plane distortion amount due to the mounting backlash of the lens itself irregularities and lenses in the device of interest.

An imaging device of the present invention that achieves the above-described object is an imaging device that forms an image of a subject on an image sensor with an imaging lens and generates image data representing the subject image with the image sensor.
An in-focus position deviation storage unit that stores a relative deviation amount of the in-focus position of each area when the image sensor is divided into a plurality of areas;
The in-focus position obtained for each area of the image sensor at the time of shooting is corrected based on the relative shift amount of each area stored in the in-focus position deviation storage unit, and the in-focus area of each area after correction is corrected. based on the position, characterized in that a focus detection unit for determining the focus position of the entire subject.

  According to the photographing apparatus of the present invention, even if there is an irregularity of the lens, the focus detection unit as a whole subject is based on the amount of in-focus position deviation stored in the in-focus position deviation storage unit. focus position of is required. Then, the in-focus position as the whole subject is obtained, and the photographing device always performs in-focus photographing.

Here, with a spatial frequency measurement unit for measuring the spatial frequency of each of the plurality of regions,
The spatial frequency measurement unit is adapted to detect the relative shift amount of the focal position of each region for each spatial frequency,
The focus position deviation storage section, the focus position shift amount of each region be those stored for each spatial frequency,
The focus detection unit measures the in-focus position obtained for each region of the image sensor in photographing, measured by the spatial frequency measurement unit for each region stored in the in-focus position shift storage unit. It is preferable that correction is performed based on the shift amount corresponding to the spatial frequency for each region, and the in-focus position of the entire subject is obtained based on the in-focus position of each region after correction.

  Spatial frequency (the regions when dividing the object) portion part of a subject that photography is known to be different from the case of photographing an object. Further, either taking a landscape as a subject, the spatial frequency of an object is known to vary depending on whether photographing a person as a subject.

  Therefore, if the shift amounts corresponding to various spatial frequencies are stored in the in-focus position shift storage unit so that accurate correction can be performed according to various subjects, each region is based on the shift amount. The correction according to the subject can be performed.

An image plane distortion measurement method that achieves the above-described problem is a photographing apparatus that forms a subject image on an image sensor with a photographing lens and generates image data representing the subject image with the image sensor.
An in-focus position deviation storage unit that stores a relative deviation amount of the in-focus position of each area when the imaging element is divided into a plurality of areas;
The in-focus position obtained for each area of the image sensor during shooting is corrected based on the relative shift amount of each area stored in the in-focus position deviation storage unit, and the in-focus position of each area after correction is corrected. based on the position, by using the imaging device having a focus detecting unit for obtaining the focus position of the entire object,
A detection step of detecting a plurality of areas each focus position when the flat plate and the subject,
A calculating step of calculating a relative deviation amount of the focal position of the plurality of regions,
To the displacement storage unit focusing the case, and having a storage step of storing the relative shift amount of the focal position of the plurality of regions.

  As described above, the imaging device is used to detect the in-focus position of each region by the image plane distortion amount measuring method, and the relative shift amount of the in-focus position is calculated and stored in the storage unit. If you leave, for each photographing apparatus by storing the amount of shift for each imaging device, it is possible to perform the correction appropriate to the photographing apparatus.

Here, the detection step is a step of detecting the focus position of each spatial frequency of each of the plurality of regions,
The calculation step is a step of determining a relative shift amount of the focal position of the plurality of regions for each of the spatial frequencies,
It said storage step is preferably a relative displacement amount of the focal position of the plurality of regions is a step of storing each spatial frequency.

  In this way, if it is in accordance with the spatial frequency, focus correction according to the subject can be performed with high accuracy.

  Hereinafter, embodiments of the present invention will be described.

  Figure 1 is an external view of a digital camera corresponding to an example of the imaging apparatus according to the embodiment of the present invention.

  A lens barrel 100 is provided at the center of the digital camera 1 shown in FIG. 1. A finder 101 is provided above the lens barrel 100, and a flash light emission window 102 is provided next to the finder 101. It has a built-taking lens is in the lens barrel 100, a lens such as a zoom lens and a focus lens is deployed in its taking lens. Also, the camera body upper surface is provided with an release button 103a, it is taken with the digital camera is performed when the release button 103a is depressed. Although not shown in FIG. 1, a display screen, a power switch, and the like are provided on the back side of the camera.

  FIG. 2 is a block diagram showing the internal configuration of the digital camera shown in FIG.

  This digital camera 1 is provided with a distance measuring device for measuring a subject distance using subject light obtained through a photographing lens including a zoom lens 100a and a focus lens 100b. the distance measuring device is deployed. The signal processing block 13 is also provided with a white balance adjustment unit, a YC separation unit, and the like.

  The signal processing block 13 and the JPEG encoder 16 and card I / F17 is, for example, is composed of a DSP, the DSP is controlled to CPU 10. The CPU 10 controls the operation of the digital camera in accordance with the procedure of the program recorded in the ROM 10a. When an operation signal for the release button 103a in the key block 103 is input to the CPU 10, for example, have or to perform the processing required for signal processing block 13 and the card I / F17 in the DSP notifies the processing corresponding to the release operation signal to DSP.

  First power switch is in the key block 103 will be described the operation of the digital camera 1 when it is turned on.

  When the power switch is turned on, power is supplied from the battery to the image pickup device (hereinbelow, referred to as a CCD because a CCD solid-state image pickup device is used here) 11, A / D 12 and the like shown in FIG. Become. When power to the CCD 11 is supplied, the subject in the direction directed towards the photographing lens including the zoom lens 100a and the focus lens 100b is imaged on the CCD 11. At this time, the CPU 10 gives an instruction to output image data representing the subject imaged on the CCD 11 via the TG 11a at every predetermined time, causes the CCD 11 to output the image data, and further the A / D 12 Then, image data is supplied to the signal processing block 13 at predetermined time intervals.

  Since it is necessary to output focused image data when outputting the image data to the CCD 11, in the digital camera 1 of this embodiment, the in-focus position is detected by the signal processing block 13, and the detection result is based on the detection result. and moving the focus lens 100b to the focusing position corresponding to the detection result by rotating the focus motor 112 instructs the driver 111 from the CPU 10. When the focus lens 100b is moved based on an instruction from the CPU 10, a pulse train is supplied from the driver 111 to the focus motor 112, and the focus lens 100b is moved by the number of pulses forming the pulse train. And the CPU10 and the signal processing block 13 and the driver 111 and the focus motor 112 and the focus lens 100b hits the focus detection section according to the present invention. 2 also shows a zoom motor 114 for the zoom lens 100a and a driver 113 for driving the zoom motor 114. Therefore, the focus motor 112 and the driver 111 for the focus motor 112 are combined with the drive unit. 110.

  Here, the signal processing block 13 detects the contrast from the field luminance, calculates the AF evaluation value from the contrast, and sets the peak of the AF evaluation value as the in-focus position. Further, in the digital camera 1 of this embodiment, the relative shift amount when the imaging surface of the CCD 11 is divided into a plurality of areas is detected for each area for the purpose of improving the accuracy of the in-focus position, and the entire subject is detected. It employs a configuration for detecting the focused position.

  Then, it is possible to move the focus lens 100b to accurately focus position, always subject in focus is imaged CCD 11. Image data representing the subject imaged on the CCD 11 is output to the signal processing block 13 via the A / D 12. Image processing such as YC separation is performed on the image data supplied from the CCD 11 by the signal processing block 13, and the image processed image data is output to the DRAM 14 at every predetermined time, and successively to the DRAM 14 at every predetermined time. data will be stored. The image data stored in the DRAM 14 is supplied to the image display unit 15 at a predetermined time. The image display unit 15 switches the subject based on the image data supplied at the predetermined time and sequentially displays them on the display screen. To do. Thus when the subject photographing lens on the display screen of the image display portion was captured is displayed, the display screen becomes the viewfinder instead.

  When the release button 103a is pressed at a photo opportunity while viewing the subject displayed on the display screen, a signal for performing exposure for a predetermined time from the timing when the release button 103a is pressed is supplied from the TG 11a to the CCD 11. The After the predetermined time has elapsed, image data is output from the CCD 11. The output image data is supplied to the signal processing block 13 via the A / D 12, and the image data processed by the signal processing block 13 is further supplied to the JPEG encoder 16. The JPEG encoder 16 compresses the image data, and an image file composed of the compressed image data and information related to the compression is recorded on the memory card 18 under the control of the card I / F 17.

  As described above, the in-focus position is detected by the signal processing block 13, but in the digital camera 1 of the present embodiment, the unevenness and mounting of the lens (for example, the focus lens itself, the zoom lens itself) listed in the problem are not fixed. Before shipping this digital camera, measure the amount of distortion on the lens surface and the amount of distortion on the lens surface so that the in-focus position can be detected. so that prestored in EERPOM10b the image plane distortion amount. The EEPROM10b hits the positional deviation storage section according to the present invention.

  Here in advance before shipment of the photographing device, the image plane distortion measuring method when storing the image plane distortion amount EEPROM10b, will be described with reference to FIGS. 3 to 7.

  3 to 5 are diagrams showing divided areas on the imaging surface of the CCD.

  Each divided area in FIG. 3 to FIG. 5, since those focusing lens as described above is driven by a pulse train the number of pulses forming the pulse train are respectively shown. FIG. 3 shows the best focus pulse number (a11, a12...) In consideration of the shift amount of the in-focus position caused by the geometric shape of the curved surface of the lens, and FIG. FIG. 5 shows the relative shift amounts (p11-a11, p12-a12,...) Calculated from these pulse numbers, respectively.

  FIG. 6 is a diagram showing a measurement system when the image plane distortion amount of each divided region of the image sensor is measured by this digital camera, and FIG. 7 is a flowchart showing a measurement procedure measured by the measurement system.

  As shown in FIG. 6, the plane plate 2 is placed at a position captured by the photographing lens of the digital camera 1 and photographing is performed according to the procedure of FIG. 7, and the relative shift amount of each divided region shown in FIG. 5 is stored in the EEPROM. the measurement is made.

  6, the measurement method will be described with reference to FIG.

  In the digital camera 1 of this embodiment as described above, the signal is supplied to a pulse train from the driver 111 to the motor 112 based on an instruction from the CPU 10. Therefore, the image plane distortion amount is measured by the signal processing block 13 by photographing the reference flat plate 2 before shipping the digital camera, and the CPU 10 stores the number of pulses corresponding to the image plane distortion amount in the EEPROM 10b. I remember it.

  When the CPU 10 stores the number of pulses in the EERPOM 10b, the signal processing unit is caused to measure the in-focus positions (see FIG. 4) of the 64 areas when the flat plate is the subject in the detection step S701, and in the next calculation step S702. Then, a subtraction is performed between the number of pulses required to move to each of the measured in-focus positions and the number of best focus pulses shown in FIG. see FIG. 5) to seek, and stores the deviation amount in the EEPROM in the storage step S703.

  In this way, the relative shift amounts of the focus positions of a plurality of areas are stored in the EEPROM, and the stored relative shift amounts are referred to at the time of shooting to calculate an appropriate AF evaluation value and focus. lens always focus lens position corresponding to the focal point is driven is arranged.

  For this reason, an error does not occur in the AF evaluation value, and comfortable shooting is always performed.

  FIG. 8 is a diagram illustrating an example of a flat plate used when measuring the amount of distortion for each spatial frequency.

  The signal processing block 13 of the digital camera of the present embodiment is provided with a spatial frequency measuring unit that measures the spatial frequency, and the spatial frequency measuring unit can measure the spatial frequency at the time of measurement before shipment. Using this spatial frequency measurement unit may further perform accurate correction.

  FIG. 8 shows one surface of a plane plate in which a luminance distribution for causing the spatial frequency measurement unit in the signal processing block 13 of the digital camera of FIG. 2 to measure the spatial frequency is attached to vertical stripes. Is taken, the horizontal spatial frequency is measured by the spatial frequency measuring unit in the signal processing block of the digital camera, and further measured according to the flow of FIG. 7, and the amount of distortion corresponding to the horizontal spatial frequency is stored in the EEPROM 10b. The If the interval of vertical stripes in this case is determined by taking each of those flat plates are prepared a plurality of kinds of different flat plate, the strain amount corresponding to various horizontal spatial frequencies are stored in EERPOM. Still to prepare a flat horizontal stripes can also measure the amount of distortion corresponding to the vertical spatial frequency.

  As described above, when the amount of distortion corresponding to the spatial frequency is measured and the relative shift amount corresponding to various spatial frequencies is stored in the EEPROM 10b, the shift amount in the EEPROM according to the subject obtained by photographing. Is referred to and high-precision focus correction is performed.

It is an external view of the digital camera corresponding to an example of the imaging apparatus according to the embodiment of the present invention. FIG. 2 is a configuration block diagram illustrating an internal configuration of the digital camera in FIG. 1. It is a figure which shows the division area of an image pick-up element, Comprising: It is the figure by which the best focus pulse number was shown by each division area. A diagram showing divided areas of the image pickup element, a view number of pulses is shown corresponding to the distortion amount obtained by measuring the respective divided regions. It is a figure which shows the divided area of an image pick-up element, Comprising: The pulse number corresponded to the amount of relative displacements to each divided area is shown. It is a figure which shows the measurement system when measuring the amount of field distortion with this digital camera. It is a flowchart illustrating a procedure of measurement to be measured by the measurement system. It is a diagram showing a configuration of a flat plate used in measuring strain amount for each spatial frequency.

Explanation of symbols

1 Digital camera 10 CPU
10a ROM
10b EEPROM
11 CCD
12 A / D
13 Signal Processing Block 14 DRAM
15 Image Display Unit 16 JPEG Encoder 17 Card I / F
18 memory card 100 lens barrel 101 finder 102 flash light emitting window 103 key block 103a release button 110 drive unit 111 driver 112 focus motor 113 driver 114 zoom motor 2 flat plate 21 flat plate (for spatial frequency measurement)

Claims (4)

A photographic device that forms a subject image on an image sensor with a photographic lens and generates image data representing the subject image with the image sensor,
An in-focus position deviation storage unit that stores a relative deviation amount of the in-focus position of each area when the image sensor is divided into a plurality of areas;
The in-focus position obtained for each area of the image sensor at the time of shooting is corrected based on the relative shift amount of each area stored in the in-focus position deviation storage unit, and the in-focus area of each area after correction is corrected. based on the position, photographing apparatus characterized by comprising a focus detection unit for determining the focus position of the entire object. Includes a spatial frequency measurement unit for measuring the spatial frequency of each of the plurality of regions,
The spatial frequency measurement unit is adapted to detect the relative shift amount of the focal position of each region for each spatial frequency,
The focus position deviation storage section, the relative shift amount of the focal position of each region be those stored for each spatial frequency,
The focus detection unit measures the in-focus position obtained for each region of the image sensor in photographing, measured by the spatial frequency measurement unit for each region stored in the in-focus position shift storage unit. The in-focus position as a whole subject is obtained based on the in-focus position of each area after correction based on a shift amount corresponding to the spatial frequency for each area. Shooting device. A photographic device that forms a subject image on an image sensor with a photographic lens and generates image data representing the subject image with the image sensor,
An in-focus position deviation storage unit that stores a relative deviation amount of the in-focus position of each area when the image sensor is divided into a plurality of areas;
The in-focus position obtained for each area of the image sensor at the time of shooting is corrected based on the relative shift amount of each area stored in the in-focus position deviation storage unit, and the in-focus area of each area after correction is corrected. based on the position, using the imaging device having a focus detecting unit for obtaining the focus position of the entire object,
A detecting step of detecting a plurality of areas each focus position when the flat plate and the subject,
A calculating step of calculating a relative deviation amount of the focal position of the plurality of regions,
And a storage step of storing a relative shift amount of the focus positions of the plurality of regions in the focus position shift storage unit. The detection step is a step of detecting a focus position for each spatial frequency of each of the plurality of regions;
The calculation step is a step of determining a relative shift amount of the focal position of the plurality of regions for each of the spatial frequencies,
4. The image plane distortion amount measuring method according to claim 3, wherein the storing step is a step of storing a relative shift amount of in-focus positions of the plurality of regions for each spatial frequency.

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