JP2018191141A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus allowing for shooting of a photograph in which the contrast between a bright part and a dark part is emphasized.SOLUTION: The imaging apparatus includes: an imaging device (103); exposure time control means (107) capable of controlling exposure time for an arbitrary pixel or pixel group of the imaging device; and scene detection means (110) for detecting a predetermined scene. The exposure time control means (107) is controlled so that the exposure level of a low luminance object becomes lower compared to an exposure level of a high luminance pixel region when the scene detection means (110) detects a scene which matches a predetermined scene.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus capable of controlling an exposure time for each pixel or each pixel group.

  Conventionally, there has been a technical disclosure regarding an apparatus and a method for realizing an imaging process by setting an exposure time for each area unit of an image sensor.

  For example, Patent Document 1 discloses a technique for realizing an exposure start time of an image pickup device by an electronic shutter and an exposure end time by a mechanical shutter operation, and individually controlling the exposure time for each pixel area. The exposure time is subtracted from the operation time of the mechanical shutter, the reset time as the exposure start time is calculated as the operation time of the electronic shutter, and the exposure time control for each area is realized.

  As a result, it is possible to eliminate the distortion of the captured image in the conventional focal plane shutter operation. In addition, an image having a wide dynamic range can be taken by adaptively controlling the exposure time in units of areas according to the brightness of the subject.

  In Patent Document 2, the exposure time is controlled for each arbitrary region by using an image sensor that can control the exposure start time of pixels in units of columns. As a result, a wide dynamic range is realized, and an image with excellent reproducibility can be obtained even for a high-contrast scene.

  In the prior art described above, with the main purpose of expanding the dynamic range, the exposure time is controlled so that the low luminance region of the subject has a long exposure time and the high luminance region has a short exposure time.

JP 2012-182657 A JP 2000-278595 A

  However, with the conventional technology disclosed in the above-mentioned patent document, it is not possible to take a photograph in which the contrast of a bright part and a dark part is emphasized. In the prior art, the main purpose is to expand the dynamic range, and control is performed so that the low luminance region of the subject has a long exposure time and the high luminance region has a short exposure time. For this reason, there is a possibility that even a dark part will be brightly photographed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus that can take a photograph in which the contrast of a bright part and a dark part is emphasized.

  To achieve the above object, the present invention provides an image sensor (103), an exposure time control means (107) capable of controlling an exposure time for each pixel or pixel group of the image sensor, And a scene detection means (110) for detecting the scene of the low brightness subject when the scene detection means (110) matches a predetermined scene, the exposure level of the low brightness subject is set lower than the exposure level of the high brightness pixel area. As described above, the exposure time control means (107) is controlled.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can image | photograph the photograph which emphasized the contrast of the bright part and the dark part can be provided.

1 is a configuration diagram of an imaging apparatus according to a first embodiment of the present invention. Assumed shooting scene in the imaging apparatus according to the first embodiment of the present invention Exposure control method in conventional imaging apparatus Exposure control method in imaging apparatus according to first embodiment of the present invention Exposure control method in imaging apparatus according to first embodiment of the present invention Exposure control method in imaging apparatus according to first embodiment of the present invention Operation screen on the imaging apparatus according to the first embodiment of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an imaging apparatus according to an embodiment of the present invention.

[Example 1]
Hereinafter, an imaging apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an imaging apparatus 100 according to an embodiment of the present invention.

  Reference numeral 101 denotes a lens group of a photographing optical system (imaging optical system), which is held so as to be able to advance and retreat in the optical axis direction. Reference numeral 104 denotes a driving unit for driving the imaging lens 101, which has a zooming function by adjusting the aperture and moving the lens back and forth.

  Reference numeral 102 denotes a focal plane shutter that adjusts the exposure time during still image shooting. Alternatively, an image sensor 103 described later may have an electronic shutter function and adjust the exposure time with a control pulse. When performing pixel-by-pixel exposure as in the present invention, the front curtain may be realized by an electronic shutter and the rear curtain may be realized by a focal plane shutter, or the configuration may be realized by an electronic shutter including the front curtain and rear curtain. A shutter driving unit 105 drives the shutter 102.

  Reference numeral 103 denotes an image sensor that converts an optical image into an electric signal. The image sensor 103 captures still images and moving images. An analog front end (not shown, hereinafter referred to as AFE) that performs gain adjustment and digital conversion on an analog image signal output from the image sensor 103 is temporarily stored in a RAM 121 described later via a CPU 110 described later. . The image sensor 103 is configured to be able to control the exposure time for each pixel or each pixel group.

  Reference numeral 107 denotes a timing generator (hereinafter referred to as TG) that controls the drive timing of the image sensor 103 and the AFE. A description will be given of a configuration in which the exposure time control is performed for each pixel or each pixel group of the image sensor 103 in the TG 107. In the present invention, the example in which the exposure control is performed by the TG 107 will be described. However, the exposure control may be performed by the inside of the image sensor 103 or by the CPU 110 or the like which will be described later.

  A display unit 108 displays a captured still image, moving image, live view, menu, and the like. Includes backside TFT and viewfinder. The display unit 108 has a built-in touch panel 111, and the user can determine the user operation by operating the rear surface TFT or the like. Reference numeral 109 denotes an operation unit for setting a shooting command, shooting conditions, and the like for still images and moving images to the CPU 110 described later. In the operation unit 109, the drive mode can be selected, and single shooting or continuous shooting can be set. Furthermore, the bulb shooting mode setting and the shutter speed change setting are also performed using the operation unit 109.

  Reference numeral 110 denotes a CPU that comprehensively controls the imaging apparatus. The CPU 110 includes an image processing unit that performs processing such as correction and compression of still images and moving images.

  Reference numeral 120 denotes a ROM that stores a program when the CPU 110 described later performs an operation. Here, the flash-ROM is shown in the present embodiment, but this is an example, and other memories may be applied as long as the access speed is at a level that does not cause a problem. Reference numeral 121 denotes a RAM that combines the function of image data storage means for storing image data from the image sensor 103 and image data processed by the CPU 110 and the function of a work memory when the CPU 110 operates. is there. In the present embodiment, these functions are performed by the RAM 121. However, other memories may be applied as long as the access speed is a level that does not cause a problem.

  Reference numeral 130 denotes a memory card, which is a detachable recording medium for recording still image data and moving image data captured by the imaging apparatus 100. A memory card slot 126 is a slot into which the memory card 130 can be attached and detached.

  FIG. 2 is a diagram showing an assumed shooting scene in the present invention. Reference numeral 200 denotes a photograph that assumes one scene such as a birthday. In a dark scene, people (202, 203) are surrounded by a bright candle light (201). In such a scene, generally, the periphery of the person (202, 203) becomes dark when the periphery of the candle light (201) is controlled to be appropriately exposed.

  On the other hand, when the peripheral portion of the person (202, 203) is controlled to be appropriately exposed, not only the periphery of the candle light (201) is overexposed but also the background (204) portion is reflected, and the atmosphere is changed. It will be a damaged photo.

  FIG. 3 is a diagram showing the exposure time and the luminance level for each pixel area when the assumed shooting scene as shown in FIG. 2 is shot with a conventional imaging apparatus. 2 shows the exposure time and the luminance level for each pixel area of the candle peripheral portion 201, the human peripheral portion 202, the human peripheral portion 203, and the background portion 204 in FIG.

  As shown in FIGS. 3A and 3C, when the image is taken with a conventional imaging device, the exposure times of all the pixel regions are the same.

  FIG. 3B shows the luminance level of each pixel area when the peripheral portion of the candle (201) is controlled to be appropriately exposed. FIG. 3D shows the luminance level of each pixel area when the peripheral portion of the person (202, 203) is controlled to be appropriately exposed. As shown in FIG. 3B, when the candle peripheral part is appropriately exposed, the human peripheral part becomes dark. On the other hand, when the peripheral portion of the person is appropriately exposed as shown in FIG. 3D, the peripheral portion of the candle becomes bright and the background portion becomes bright and appears in the photograph.

  FIG. 4 is a diagram showing the exposure time and the luminance level for each pixel region when the assumed shooting scene as shown in FIG. 2 is shot by the imaging apparatus of the present invention.

  FIGS. 4A and 4B show a case where exposure control is performed so that the peripheral portion of the candle is appropriately exposed, and the exposure time is controlled to be long so that the peripheral portion of the person becomes bright, while the exposure time of the background portion is shown. Control short. As a result, it is possible to take a photograph in which the contrast between the bright and dark portions is enhanced and the peripheral portion of the person is appropriately exposed.

  4 (C) and 4 (D) show a case where exposure control is performed so that a person's peripheral part is appropriately exposed, and the exposure time is controlled to be short so that the candle's peripheral part is not too bright, while the background part is exposed. Control time short. As a result, it is possible to take a photograph in which the contrast between the bright and dark portions is enhanced and the peripheral portion of the person is appropriately exposed.

  FIG. 5 is a diagram showing an assumed shooting scene according to the present invention, as in FIG. FIG. 2 shows a state in which exposure control is performed concentrically around the candle light of a high-luminance subject. As shown in FIG. 5C, control is performed so that the exposure time is gradually shortened, such as a concentric circle 505 and a concentric circle 506, centering on a region 501 centering on candle light. In addition, the shadow portion 507 is controlled to have a sufficiently short exposure time so as not to make an unnatural photograph.

  On the other hand, the human region (502) and the human region (503) are controlled so as to achieve appropriate exposure by increasing the exposure time. As a result, as shown in FIG. 5D, the contrast between the bright portions (501, 505, 506) centered on the candle light and the dark portions (507, 504) is enhanced, and the human peripheral portion (502) , 503) makes it possible to take a picture with appropriate exposure. Furthermore, by controlling the exposure time in a concentric manner in the bright part centered on the candle light, it is possible to take a picture with natural and contrast enhanced.

  FIG. 6 is a flow control showing an example of subject discrimination in the CPU 110 during photometry. S601 is a step of performing spotlight determination. The presence or absence of a spotlight is determined from the distribution of the high luminance area. Specifically, it is determined that there is a spotlight when there is a high luminance area above a predetermined level in a low luminance background below a predetermined level and the subject in the high luminance area is in focus. If there is a spotlight, the process proceeds to step S602; otherwise, the process proceeds to step S605.

  S602 is a step of determining whether the subject is free of people or faces. If there is a person or face, the process proceeds to step S603, and if not, the process proceeds to step S604.

  S603 is a step of exposing each pixel to the detected high-luminance region and low-luminance region. The spotlight-determined area is a high-luminance subject, and the background area is a low-luminance subject. The exposure time of the low-luminance subject area is shortened with respect to the high-luminance subject area. In addition, exposure time control is performed concentrically around a high-luminance subject. In addition, the exposure time is lengthened so that a region where a person or a face is detected is appropriately exposed. As a result, it is possible to take a photograph in which the contrast between the bright and dark portions is enhanced and the peripheral portion of the person is appropriately exposed.

  S604 is a step of controlling the exposure time so that the exposure time of the low-luminance area is shortened with respect to the detected high-luminance area, as in S603. However, since human and face detection is not performed, exposure control associated with human and face detection is not performed.

  S605 is a step of determining a point light source such as a candle light. The presence or absence of a point light source is determined from the distribution of the high luminance area. Specifically, it is determined that there is a point light source when there is a high luminance area of a predetermined level or higher in a low luminance background of a predetermined level or lower. A point light source is determined when the high luminance region is narrower and the luminance level is higher than the high luminance region at the time of spotlight determination. If there is a point light source, the process proceeds to step S606, and if not, the process proceeds to step S609.

  S606 is a step for determining whether or not the subject has a person or a face, as in step S602. If there is a person or face, the process proceeds to step S607, and if not, the process proceeds to step S608.

  S607 is a step of exposing each pixel to the detected high luminance region and low luminance region. The exposure time of the low-luminance subject area is shortened with respect to the high-luminance subject area, with the point light source determined area as the high-luminance subject and the background area as the low-luminance subject. In addition, exposure time control is performed concentrically around a high-luminance subject. In addition, the exposure time is lengthened so that a region where a person or a face is detected is appropriately exposed. As a result, it is possible to take a photograph in which the contrast between the bright and dark portions is enhanced and the peripheral portion of the person is appropriately exposed.

  S608 is a step of controlling the exposure time so as to shorten the exposure time of the low-brightness area with respect to the detected high-brightness area, as in S607. However, since human and face detection is not performed, exposure control associated with human and face detection is not performed.

  S609 is a step of determining whether or not the subject has a composition that emphasizes the silhouette. If there is a low-brightness region with an extremely low luminance level in a high-brightness region of a predetermined level or higher, the composition is determined to emphasize the silhouette. For example, a composition is assumed in which silhouettes (shadows) of people and buildings are emphasized against the sunset. Further, silhouette determination is also performed in this step for the shadow portion (507) in FIG. If it is determined that the composition emphasizes the silhouette, the process proceeds to step S610; otherwise, the process proceeds to step S611.

  S610 is a step of exposing each pixel to the detected high luminance region and low luminance region. The silhouette portion is emphasized by controlling the exposure time of the silhouette portion determined to be a low-luminance subject region to be shorter than that of other regions. As a result, it is possible to take a photograph in which the contrast between the bright and dark portions is enhanced and the peripheral portion of the person is appropriately exposed.

  S611 is a step in which the exposure time control for each pixel area is not performed, and the same uniform exposure control is performed as in the prior art.

  The flow described with reference to FIG. 6 is stored as a program in the ROM 120 and executed by the CPU 110.

  FIG. 7 is a diagram illustrating an operation example of the rear operation unit of the imaging apparatus 100. FIG. 7A is an example of a rear operation unit of the imaging apparatus 100. The display unit 108 displays a menu setting as shown in FIG. 7B and a live view image as shown in FIG. The operation unit 109 is an operation member of the imaging apparatus, and can perform menu settings and the like.

  As shown in FIG. 7B, the menu setting can set the mode of the imaging apparatus. One of the modes has a high contrast mode, and the operation unit 109 can be used to enable / disable the mode. Here, the pixel-by-pixel exposure control of the present invention may be enabled only when the high contrast mode is enabled.

  As shown in FIG. 7C, the detected areas can be displayed on the live view screen.

  Reference numeral 701 denotes a point light source detection area such as a candle light. Reference numerals 702 and 703 denote human detection areas. Reference numeral 704 denotes an area recognized as the background.

  Reference numeral 705 denotes an area newly added by the user. The user can select an area to be newly added while viewing the live view screen. Here, a user operation is detected using a touch panel built in the display unit 108.

  Reference numeral 706 denotes a user interface for changing the exposure setting of each detected area. When the detected area is selected by touch panel operation, the exposure setting of the area can be changed.

  According to the embodiment described above, it is possible to easily take a photograph in which the contrast of the bright part and the dark part is enhanced and the peripheral part of the person is appropriately exposed.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 100 Imaging device 103 Image pick-up element 107 Timing generator 110 CPU

Claims (10)

An image sensor (103);
Exposure time control means (107) capable of controlling the exposure time for each pixel or pixel group of the image sensor;
Having a scene detection means (110) for detecting a predetermined scene;
When the scene detection means (110) matches a predetermined scene, the exposure time control means (107) is controlled so that the exposure level of the low brightness pixel area is lower than the exposure level of the high brightness pixel area. An imaging apparatus (100) characterized by: An image sensor (103);
Exposure time control means (107) capable of controlling the exposure time for each pixel or pixel group of the image sensor;
Having a scene detection means (110) for detecting a predetermined scene;
When the scene detection means (110) matches a predetermined scene, the exposure time control means (107) is controlled so that the exposure level of the high brightness pixel area is higher than the exposure level of the low brightness pixel area. An imaging apparatus (100) characterized by: An image sensor (103);
Exposure time control means (107) capable of controlling the exposure time for each pixel or pixel group of the image sensor;
Having a scene detection means (110) for detecting a predetermined scene;
When the scene detection means (110) matches a predetermined scene, the exposure time control means (107) is controlled so as to increase the exposure level of the high brightness pixel area, and the exposure level of the low brightness pixel area is lowered. The imaging apparatus (100), wherein the exposure time control means (107) is controlled so as to become. The imaging apparatus according to any one of claims 1 to 3, wherein the scene detection means (110) performs at least one of point light source detection, spotlight detection, and silhouette detection. (100). Having face detection means (110) for detecting the face of the subject;
When the face detection means (110) detects a face, the exposure time control means (107) performs exposure control of each pixel so that the exposure of the face detection area is appropriate. The imaging device (100) according to any one of claims 1 to 4. The exposure time control means (107) controls the exposure time concentrically around the light source when a light source is detected in the scene detection means (110). The imaging device (100) according to item 1. In the scene detection means (110), when the light source is detected, the exposure time control means (107) controls the exposure time concentrically around the light source, and detects a low luminance area below a predetermined value, The imaging apparatus (100) according to any one of claims 1 to 4, wherein the exposure time is not controlled. A setting means (109) capable of setting a predetermined shooting mode;
The exposure time control for each pixel in the exposure time control means (107) can be performed when the high contrast mode is set by a user operation in the setting means (109). The imaging device (100) according to any one of the above. Exposure setting means (111) for arbitrarily setting the exposure level of the predetermined pixel area;
The imaging apparatus (100) according to any one of claims 1 to 8, wherein the exposure setting means (111) can arbitrarily set an exposure level of each pixel region by a user operation. A pixel area designating unit (111) capable of designating an arbitrary pixel area whose exposure time is different;
The imaging according to any one of claims 1 to 9, wherein the exposure time control means (107) controls the exposure time of the pixel area added by the pixel area specifying means (111). Device (100).