JP6260153B2 - Imaging device - Google Patents

Imaging device Download PDF

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JP6260153B2
JP6260153B2 JP2013183303A JP2013183303A JP6260153B2 JP 6260153 B2 JP6260153 B2 JP 6260153B2 JP 2013183303 A JP2013183303 A JP 2013183303A JP 2013183303 A JP2013183303 A JP 2013183303A JP 6260153 B2 JP6260153 B2 JP 6260153B2
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contrast
imaging apparatus
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JP2015050748A (en
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要平 大岡
要平 大岡
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株式会社ニコン
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Description

  The present invention relates to an imaging apparatus.

  Some imaging devices such as cameras have a function of performing so-called peaking display that displays an image on a display device in real time and indicates a high-contrast region in the imaging as a focused range.

  Recently, most cameras have an autofocus (hereinafter referred to as AF) function and an automatic exposure (hereinafter referred to as AE) function, and include a plurality of focus adjustment areas and a plurality of photometry areas used for detection of photometric information. There is also proposed a configuration in which a photometric area that can be selected from among a plurality of photometric information is selected according to the number of focus adjustment areas (see Patent Document 1).

JP 2000-75352 A

By the way, in a photographing apparatus equipped with an AF function, it is determined that a focused place is likely to be a main subject, and therefore, exposure by automatic exposure (hereinafter referred to as AE) is performed with luminance information in the AF area and other luminance information Many are determined using and.
However, since the AF area is not used during MF, the main subject intended by the user cannot be determined from the position. As a result, it is impossible to determine the exposure based on the focus position, and it is difficult to automatically obtain an appropriate exposure.

  An object of the present invention is to provide an imaging apparatus capable of obtaining appropriate exposure even during manual focus.

  The imaging apparatus of the present invention includes an AF area selection unit, an imaging unit that captures an image by an optical system, the imaging unit that divides the imaging unit into photometric areas and performs photometry in each photometric area, and the AF When the area is selected, exposure control is performed to perform exposure calculation based on the photometric value of the photometric area corresponding to the selected AF area, and when the AF area is not selected, the image of each photometric area And a control unit that performs high-contrast area-weighted exposure control that selects a high-contrast area by calculating the contrast of the high-contrast area and performs an exposure calculation based on a photometric value of the high-contrast area.

  According to the present invention, it is possible to provide an imaging apparatus capable of obtaining appropriate exposure even during manual focus.

1 is a conceptual configuration diagram of a camera to which a first embodiment of the present invention is applied. It is a block block diagram of the control system of a camera. It is a control flowchart of automatic exposure calculation including high contrast area weighted exposure control. It is an image figure which shows the whole imaging | photography screen. It is a graph which shows the mixture ratio with respect to the BV value of the brightness | luminance according to the magnitude | size of the peaking area.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a conceptual configuration diagram of a camera 100 to which the first embodiment of the present invention is applied. FIG. 2 is a block configuration diagram of a control system of the camera 100.

  The camera 100 includes an operation unit 101, a lens 102, a display unit 103, an imaging unit 104, a memory card slot 106, a monitor 107, a prism 108, an eyepiece unit 109, a mirror 110, and a shutter 111. The photometric sensor 112 and the photometric lens 113 are provided. In addition, the camera 100 includes a control unit 200 that performs overall control of the camera 100.

The operation unit 101 includes input members operated by the user, such as a power switch, a release button, a zoom button, a cross key, an enter button, a play button, and a delete button.
As shown in FIG. 2, the operation unit 101 includes a scene mode selection unit 101A, a photometry mode selection unit 101B, and a focus mode selection unit 101C.
The scene mode selection unit 101A can select any one of shooting scenes such as portrait, landscape, sports, night view, and close-up.
The photometry mode selection unit 101B can select any one of center-weighted average photometry, multi-pattern photometry, spot photometry, and the like, for example.

  The in-focus mode selection unit 101C can select either an autofocus (AF) mode or a manual focus (MF) mode. In addition, the focusing mode selection unit 101C determines that the attached lens 102 is also an MF mode if it is a non-AF compatible MF lens.

The lens 102 is an imaging optical system that forms a subject image on the imaging unit 104 described later, and is represented by a single lens as a representative in the figure, but is composed of a plurality of optical lenses.
The display unit 103 is, for example, a polymer-dispersed liquid crystal, and this display is superimposed on the light guided by the mirror 110 through the lens 102. The light on which the display is superimposed passes through the prism 108 and is guided to the eyepiece 109 and the photometric sensor 112.

  The photometric sensor 112 is an image sensor composed of a plurality of pixels such as a CMOS and a CCD. An image captured by the photometric sensor 112 is sent to the control unit 200.

  The imaging unit 104 is, for example, an image sensor such as a CMOS or a CCD. At the time of imaging, the mirror 110 is raised, the shutter 111 is opened, and the subject image formed by the lens 102 is captured with the exposure determined by the control unit 200. The Then, an image signal obtained by imaging is output to the control unit 200.

The memory card slot 106 is a slot for inserting a memory card as a storage medium, and writes and records the image file output from the control unit 200 on the memory card.
Further, the memory card slot 106 reads an image file stored in the memory card based on an instruction from the control unit 200.

  The monitor 107 is a liquid crystal monitor mounted on the back surface of the camera 100 or the like. The monitor 107 displays a through image captured by the imaging unit 104, an image stored in the memory card, a setting menu for setting the camera 100, and the like. Further, so-called peaking area display is performed in which a high contrast region is displayed over the through image.

The control unit 200 includes a CPU, a memory, and other peripheral circuits.
Note that the memory constituting the control unit 200 includes an SDRAM and a flash memory. The SDRAM is a volatile memory, and is used as a work memory for developing a program when the CPU executes a program, or as a buffer memory for temporarily recording data. The flash memory is a non-volatile memory in which data of a program executed by the control unit 200, various parameters read during program execution, and the like are recorded.

As shown in FIG. 2, the control unit 200 includes an image processing unit 210, a contrast detection unit 220, and an exposure control unit 230 as functional units.
The image processing unit 210 generates a predetermined image format, for example, JPEG format image data (hereinafter, main image data) based on the image signal input from the imaging unit 104, and generates an image file to which additional information is added. To the memory card slot 106.

  The contrast detection unit 220 obtains contrast information of each area obtained by subdividing the imaging range in the image captured by the imaging unit 104 and image-processed by the image processing unit 210. This contrast information is used for so-called peaking area display for displaying a high contrast region in the through image on the monitor 107.

  The exposure control unit 230 is based on the selection results in the scene mode selection unit 101A, the photometry mode selection unit 101B, and the focus mode selection unit 101C, the control data held in the memory, and the photometry information input from the photometry sensor 112. To determine the exposure.

  Then, the control unit 200 drives the exposure mechanism 120 (the imaging unit 104, the mirror 110, the shutter 111, etc. in FIG. 1) based on the exposure set by the exposure control unit 230 at the time of shooting to perform automatic exposure. The image processing unit 210 generates image data and records it on the recording medium 130 such as a memory card via the memory card slot 106.

Here, the control unit 200 performs high-contrast area weighted exposure control when manual focus (MF) is set in the focusing mode selection unit 101C or when the mounted lens 102 is an MF lens. Do.
In addition, in the scene mode selection unit 101A, for example, the control unit 200 performs high contrast region weighted exposure control in the portrait mode and macro mode, and performs high contrast region weighted exposure control in the landscape mode and night scene mode. Absent.

  The high contrast area weighted exposure control is to set the exposure based on the photometric information by the photometric sensor 112 in the high contrast area detected by the contrast detecting unit 220 when the exposure control unit 230 determines the exposure.

Next, high contrast region weighted exposure control will be described along the control flow shown in FIG. 3 with reference to FIGS. 4 and 5 in addition to FIGS. 1 and 2 described above. In the drawings and the following description, “step” is also abbreviated as “S”.
FIG. 3 is a control flowchart of automatic exposure calculation including high contrast region weighted exposure control. FIG. 4 is an image diagram of the shooting screen and represents the entire shooting screen 10. FIG. 5 is a graph showing the blending ratio with respect to the BV value of the luminance according to the size of the peaking area.
The photometric sensor 112 has a plurality of pixels, and now has a total of 40 pixels of 8 × 5.

[Step 101]
The focusing mode selection unit 101C determines whether the focusing mode of the camera 100 is the AF mode or the MF mode.
If it is determined that the AF mode is selected, the process proceeds to step 102. On the other hand, if the MF mode is determined, the process proceeds to step 103.

[Step 102]
This is a case where the AF mode is set and AF is used for focusing.
Here, the brightness of the AF area is calculated.
That is, reference numeral 11 shown in FIG. 4A represents an AF area, and the user moves the AF area 11 to a desired position to focus on the person who is the main subject. The average luminance value of the pixels 21 and 22 where the AF area 11 exists is set as the luminance of the AF area, BvAfArea. Then, the process proceeds to Step 105.

[Step 103]
This is a case where the MF mode is set and the focus is adjusted manually.
Here, a portion (peaking area) with high contrast is selected from the detection result of the contrast detection unit 220 in the entire photographing screen 10, and the process proceeds to Step 104.
Portions indicated by fine hatching in FIG. 4B represent peaking areas 31 and 32 having high contrast in the photographing screen 10.

[Step 104]
The BV value of the pixel in the photometric sensor 112 that overlaps with the high contrast portion (peaking area) selected in step 103 is obtained.
That is, the peaking areas 31 and 32 shown in FIG. 4B are considered to be in focus. Therefore, the average luminance value BvMFPeak in the areas of the pixels 41, 42, and 43 in the photometric sensor 112 that overlap with the peaking areas 31 and 32 is obtained. Then, the process proceeds to Step 105.

[Step 105]
Perform a known automatic exposure calculation. If the AF mode is determined in step 101, BvAfArea is substituted for BvFocus, and if the MF mode is determined, BvMFPeak is substituted for BvFocus to perform a known automatic exposure calculation.
Ie
CtrlBv = f (BvFocus, BvAberage, ...) ... Formula (1)
It becomes. here,
CtrlBv: BV value for controlling the camera, so-called exposure.
BvFocus: the brightness around the AF area, here the brightness values of the pixels 203 and 204.
BvAverage: Average brightness value of the entire screen.
F: This is a function for calculating a known automatic exposure, and includes the above contents as an input value.

  As described above, in the MF mode, based on the luminance value of the pixel in the photometric sensor 112 (and the average luminance value of the entire screen) that overlaps with a high-contrast portion (peaking area) in the entire shooting screen. To set the BV value. Thereby, at the time of MF, it is considered that the contrast is high and the subject is in focus. Therefore, it is possible to obtain an appropriate exposure for a subject that is very likely to be a main subject.

In the MF mode, if there is no peaking area, BvMFPeak becomes undefined. Also, if the peaking area is narrow and there are very few pixels overlapping with the photometric sensor 112, the exposure calculation may become unstable.
Therefore, the number of pixels overlapping with the photometric sensor 112 is N_PeakPixel, and BvMFPeak is stabilized as follows. Where Sth_PeakPixel1,
Sth_PeakPixel2 is the value of the number of pixels optimized by experiment. For example, 1/2 of the total number of pixels or 1/4 of the total number of pixels may be used.

If N_PeakPixel <Sth_PeakPixel1
k_Peak = 0
If Sth_PeakPixel1 ≦ N_PeakPixel ≦ Sth_PeakPixel2
k_Peak = (N_PeakPixel−Sth_PeakPixel1) / (Sth_PeakPixel2−Sth_PeakPixel1)
If Sth_PeakPixel2 <N_PeakPixel
k_Peak = 1
FIG. 5 is a graph showing the relationship of k_Peak to N_PeakPixel.
And
BvMFPeak = (BvMFPeak × k_Peak) + (BvAverage × (1-k_Peak))

Thereby, when the overlapping area is narrow, the luminance of the peaking area is gradually replaced with the average luminance of the entire screen. That is, when the peaking area is narrower than a predetermined pixel number range, the ratio of the luminance of the peaking area to the BV value is reduced according to the narrowness. As a result, stabilization can be achieved.
Here, the luminance of the peaking area is replaced with the average luminance of the entire screen. However, when the central average luminance BvCenter, the central important luminance BvCenterWt, or the like is selected in the photometry mode selection unit 101B, these luminances are selected. May be used.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
Since the configuration of the imaging apparatus according to the second embodiment of the present invention is a component having the same function as that of the first embodiment described above, description thereof is omitted.

  The second embodiment differs from the first embodiment in that spot metering is selected by the metering mode selection unit 101B, and when there is a peaking area of a predetermined size corresponding to spot metering, it overlaps with that peaking area. The luminance value of the pixel of the photometric sensor 112 is directly used as the BV value. If the peaking area does not reach a predetermined size corresponding to spot metering, the luminance value of spot metering centered on the normal screen center is replaced according to the size.

That is,
BvMFPeak = (BvMFPeak × k_Peak) + (BvSpot × (1-k_Peak))
As
CtrlBv = BvFucus (= BvMFPeak) ... Formula (2)
And
In addition,
BvSpot: Spot metering brightness value.

  Thereby, in the case of spot metering, spot metering can be performed on a portion that is considered to be high in contrast and in focus. In other words, spot metering can be performed on a subject that is in focus and the subject can be photographed with appropriate exposure.

As described above, this embodiment has the following effects.
(1) According to the present embodiment, at the time of manual focus, the luminance value of the pixel in the photometric sensor 112 (and the average luminance value of the entire screen) that overlaps with a high-contrast portion (peaking area) in the entire shooting screen. The BV value is set based on (1)), and it is considered that the contrast is high and the subject is in focus. Therefore, it is possible to obtain an appropriate exposure for a subject that is very likely to be a main subject.

(2) When the peaking area is small, by gradually replacing the luminance of the peaking area with the average luminance, it is possible to prevent the exposure calculation from becoming unstable and obtain a stable exposure.
(3) In the case of spot metering, spot metering is performed on the subject in focus by setting the BV value based on the luminance value of the pixel of the metering sensor 112 that overlaps the peaking area. Therefore, it is possible to shoot with an appropriate exposure for the target subject.

(Deformation)
The present invention is not limited to the above-described embodiment, and various modifications and changes as described below are possible, and these are also within the scope of the present invention.
(1) In the above embodiment, high-contrast area weighted exposure control is performed when the focus mode is the manual focus mode or when the mounted lens is an MF lens and when the photometry mode is the spot photometry mode. . In addition to this, a switch for switching ON / OFF of high contrast area weighted exposure control may be provided so that the photographer can select.

  Although the present embodiment exemplifies a single-lens reflex camera, the present invention is not limited to this, and may be applied to a mirrorless lens interchangeable camera or a lens-integrated camera.

  In addition, although embodiment and a deformation | transformation form can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiment described above.

  DESCRIPTION OF SYMBOLS 100: Camera, 101: Operation part, 101A: Focusing mode changeover switch, 101B: Photometry mode changeover switch, 104: Imaging part, 112: Photometry sensor, 200: Control part, 220: Contrast detection part, 230: Exposure control part 233: Focusing mode determination unit, 234: Exposure control unit, 235: Photometry mode determination unit, 10: Imaging range, 31, 32: Peaking area

Claims (8)

  1.   A selection unit for selecting an AF area;
      An imaging unit for imaging an image by an optical system;
      A photometric unit that divides the imaging unit into photometric areas and performs photometry in each photometric area;
      When the AF area is selected, exposure control is performed to perform exposure calculation based on the photometric value of the photometric area corresponding to the selected AF area. When the AF area is not selected, each photometric area A control unit that performs high-contrast area-weighted exposure control that selects a high-contrast area by obtaining the contrast of the image, and performs an exposure calculation according to a photometric value of the high-contrast area;
    An imaging apparatus comprising:
  2.   The imaging apparatus according to claim 1,
      The high contrast region is a photometric area in which the contrast of the image is higher than a predetermined value.
      Imaging device.
  3. The imaging apparatus according to claim 1 or 2,
    A focus mode selection section is provided to select whether the focus mode is auto focus mode or manual focus mode.
    The control unit performs the high-contrast area weighted exposure control when the focusing mode is the manual focus mode;
    An imaging apparatus characterized by the above.
  4. The imaging apparatus according to any one of claims 1 to 3 ,
    A scene mode selection unit capable of selecting one of a plurality of shooting scene modes in which shooting is performed under shooting conditions corresponding to the selected mode,
    The control unit determines whether to perform the high-contrast area weighted exposure control according to the selected shooting scene mode;
    An imaging apparatus characterized by the above.
  5. The imaging apparatus according to any one of claims 1 to 4 , wherein:
    A metering mode selector that can select one of a plurality of metering modes including spot metering mode,
    The controller performs the high-contrast area-weighted exposure control when the metering mode is the spot metering mode;
    An imaging apparatus characterized by the above.
  6. The imaging apparatus according to any one of claims 1 to 5 ,
    Has multiple exposure control modes,
    The control unit selectively performs normal exposure control based on only the photometry result by the photometry unit and the high contrast region weighted exposure control according to the set exposure control mode,
    An imaging apparatus characterized by the above.
  7. The imaging device according to any one of claims 1 to 6 ,
    According to the size of the high contrast region , the control unit
    First photometry information by the photometry unit in the high contrast region;
    Performing the high-contrast area-weighted exposure control by changing the blending ratio of the second photometric information by the photometry unit with respect to an area that includes the high-contrast area and is wider than the high-contrast area;
    An imaging apparatus characterized by the above.
  8. The imaging apparatus according to claim 7 ,
    The control unit performs the high-contrast region-weighted exposure control by reducing the blending ratio of the first photometric information to the second photometric information as the high-contrast region is smaller.
    An imaging apparatus characterized by the above.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2631217B2 (en) * 1987-11-04 1997-07-16 キヤノン株式会社 Automatic exposure control device
JP4124874B2 (en) * 1998-08-31 2008-07-23 キヤノン株式会社 camera
JP4264553B2 (en) * 2006-06-12 2009-05-20 ソニー株式会社 Image processing apparatus, imaging apparatus, image output apparatus, method and program in these apparatuses
JP2013128240A (en) * 2011-12-19 2013-06-27 Sanyo Electric Co Ltd Electronic camera

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