JP2017098613A - Imaging apparatus, its control method, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically select a photographic mode that has a satisfactory SNR in photographing as in a dark place, regardless of a condition of a subject.SOLUTION: A distance measurement part 110 obtains distance information by measuring the distance of a subject located in an image photographing range from a camera. In a first photographing mode in which photographing is carried out by exerting tilt control in which an angle formed by the optical axis of an imaging optical system 101 and the imaging surface of an imager 102 is controlled, a tilt angle and a first diaphragm value are obtained for focusing on all subjects located in the photographing range. In a second photographing mode in which photographing is carried out, with the optical axis of the imaging optical system intersecting the imaging surface of the imager, a second diaphragm value is obtained for focusing on all subjects located in the photographing range. On the basis of the result of a comparison between the first and second diaphragm values, a photographing mode selection part 109 selects the first or second photographing mode.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an imaging apparatus including a tilt-driven lens or a tilt-driven imaging element, a control method thereof, and a control program.

  Conventionally, at the time of shooting, the following first or second method is used in order to obtain an image focused on a plurality of subjects at different distances from the imaging device. The first method is a method of obtaining a depth of field that can include a plurality of subjects with an appropriate aperture value (see Patent Document 1). Hereinafter, photographing using the first technique is referred to as normal photographing.

  On the other hand, in the second method, the imaging optical system is tilted with respect to the imaging element surface by tilting the imaging optical system using Shine-Pluff's law, which will be described later, and a plurality of distances from the imaging element are different. A focused image is obtained for the subject (see Patent Document 2). Hereinafter, shooting using the second method is referred to as tilt shooting.

JP-A-62-52538 JP-A-5-53166

  By the way, in an imaging apparatus such as a surveillance camera, in order to recognize a subject even in a dark place (low illuminance environment), the aperture is opened as much as possible, and shooting is performed with a small F value to obtain a high SNR (Signal to Noise ratio). It is necessary to secure. However, when there are a plurality of subjects, as will be described later, which of normal photographing and tilt photographing can focus on all subjects with a smaller F value varies depending on the state of the subject.

  Therefore, in an environment where the situation of the subject changes every moment, as described in Patent Documents 1 and 2, an imaging apparatus using either normal photography or tilt photography can deal with the situation of the subject. Have difficulty. As a result, shooting continues in an inappropriate shooting mode, particularly when shooting in a dark place.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus capable of automatically selecting a shooting mode with a good SNR in shooting in a dark place regardless of the state of the subject, a control method thereof, and a control program. is there.

  In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus that includes an imaging element on which an optical image is formed via an imaging optical system and obtains an image according to the output of the imaging element. The first imaging mode for performing imaging by performing tilt control for controlling the angle between the lens main surface of the imaging optical system and the imaging plane, and the lens main surface of the imaging optical system and the imaging plane are orthogonal to each other Selection means for selecting one of the second shooting modes for shooting in a state, and distance measuring means for measuring distance from the imaging device to a subject existing in the shooting range of the image to obtain distance information; A first computing means for obtaining a tilt angle and a first aperture value for focusing a plurality of subjects existing in the photographing range in the first photographing mode; and in the second photographing mode. Multiple subjects within the shooting range. Second calculating means for obtaining a second aperture value for causing the first aperture value to be selected, wherein the selecting means is based on a result of comparison between the first aperture value and the second aperture value. One of the second shooting modes is selected as a selected shooting mode.

  A control method according to the present invention is a method for controlling an imaging apparatus that includes an imaging element on which an optical image is formed via an imaging optical system and obtains an image according to an output of the imaging element. Shooting is performed in a first shooting mode in which shooting is performed by performing tilt control for controlling the angle between the lens main surface and the imaging surface, and the lens main surface of the imaging optical system and the imaging surface are orthogonal to each other. A selection step of selecting one of the second shooting modes, a distance measurement step of measuring distance from the imaging device to a subject existing in the shooting range of the image, and obtaining distance information; and the first step A first calculation step for obtaining a tilt angle and a first aperture value for focusing on a plurality of subjects existing in the shooting range in the shooting mode, and in the shooting range in the second shooting mode. Focus on multiple existing subjects And a second calculation step for obtaining a second aperture value for the first imaging mode based on a comparison result between the first aperture value and the second aperture value in the selection step. One of the second shooting modes is selected as a selected shooting mode.

  A control program according to the present invention is a control program used in an imaging apparatus that includes an imaging element on which an optical image is formed via an imaging optical system and obtains an image according to an output of the imaging element. A first photographing mode for performing photographing by performing tilt control for controlling an angle formed between the lens main surface of the imaging optical system and the imaging surface, and the lens main surface of the imaging optical system and the connection. A selection step for selecting one of the second shooting modes for shooting in a state where the image planes are orthogonal to each other, and a distance information from the imaging device to a subject existing in the shooting range of the image is obtained. A distance measurement step, a first calculation step for obtaining a tilt angle and a first aperture value for focusing on a plurality of subjects existing in the shooting range in the first shooting mode, and the second of In the shadow mode, a second calculation step for obtaining a second aperture value for focusing on a plurality of subjects existing in the shooting range is executed, and in the selection step, the first aperture value and the first aperture value are calculated. One of the first shooting mode and the second shooting mode is selected as a selected shooting mode based on a comparison result with an aperture value of 2.

  According to the present invention, it is possible to appropriately select an aperture value while focusing on a subject existing in the photographing range, and as a result, an image having a good SNR in photographing in a dark place or the like can be obtained regardless of the state of the subject. be able to.

It is a figure for demonstrating a Shine-Pluff's law, (a) is a figure which shows arrangement | positioning of an image pick-up element and a lens in normal imaging | photography, and the positional relationship of a focusing surface, (b) inclined the lens with respect to the image pick-up element. It is a figure which shows a state. It is a figure which shows an example of the image acquired by the 1st imaging | photography scene. FIG. 3 is a diagram showing a model of an arrangement relationship of subjects in the shooting scene shown in FIG. 2. FIG. 4 is a diagram showing a state in which all the subjects are focused by normal photographing with respect to the arrangement of the subjects shown in FIG. 3. FIG. 4 is a diagram illustrating a state in which all the subjects are focused by tilt shooting with respect to the arrangement of the subjects illustrated in FIG. 3. It is a figure which shows an example of the image obtained in the 2nd imaging | photography scene. FIG. 7 is a diagram showing a model of an arrangement relationship of subjects in the shooting scene shown in FIG. 6. FIG. 8 is a diagram illustrating a positional relationship between a focus plane center and a subject in normal photographing in the subject arrangement shown in FIG. 7. FIG. 8 is a diagram illustrating a state in which all the subjects are focused by tilt shooting with respect to the arrangement of the subjects illustrated in FIG. 7. It is a block diagram which shows a structure about an example of the camera by the 1st Embodiment of this invention. It is a flowchart for demonstrating an example of the imaging | photography process performed with the camera shown in FIG. It is a figure which shows an example of the apparent position (apparent coordinate) set by the subject coordinate calculating part shown in FIG. It is a figure which shows an example of the z-axis coordinate set by the to-be-photographed coordinate calculation part shown in FIG. It is a figure which shows the arrangement | positioning relationship between the image pick-up element shown in FIG. 1, a lens, and a focusing surface. It is a block diagram which shows the structure about an example of the camera by the 2nd Embodiment of this invention. 16 is a flowchart for explaining an example of a photographing process performed by the camera shown in FIG. It is a block diagram which shows the structure of the to-be-photographed object detection part used with the camera by the 3rd Embodiment of this invention. It is a flowchart for demonstrating the imaging | photography process performed with the camera by the 3rd Embodiment of this invention. It is a block diagram which shows the structure about an example of the camera by the 4th Embodiment of this invention. FIG. 20 is a flowchart for explaining a photographing process performed by the camera shown in FIG. 19. FIG. It is a figure which shows an example of the mask range set in the image displayed on the display part shown in FIG.

  Hereinafter, an example of an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  Here, before explaining the imaging apparatus according to the embodiment of the present invention, Shine-Pruff's law will be outlined.

  FIG. 1 is a diagram for explaining Shine-Pluff's law. FIG. 1A is a diagram showing the positional relationship between the imaging element and the lens and the focal plane in normal shooting. FIG. 1B is a diagram illustrating a state in which the lens is tilted with respect to the image sensor.

  In FIG. 1A, the image sensor 200a and the lens 201a are arranged so that the image sensor surface (imaging plane) and the lens main surface are parallel to each other, and the focusing surface 202a, the image sensor 200a, and the lens are arranged. All 201a are parallel. On the other hand, FIG. 1B shows the arrangement of the imaging element 200b and the lens 201b and the positional relationship between the focal plane 202b and the positional relationship between the focusing surface 202b in the tilt shooting using Shine-Pruff's law. Is tilted.

  A point where an extension line of the imaging element 200b and an extension line of the focusing surface 202b intersect is defined as CP. At this time, if the lens 201b is tilted so that the extension line of the lens main surface passes through the point CP, the lens 201b can be focused on the focusing surface 202b. This is called Shine-Pluff's law.

  Here, the above-described Shine-Pluff's law will be described by taking two shooting scenes as an example.

  FIG. 2 is a diagram illustrating an example of an image obtained in the first shooting scene.

  In the image (captured image) 10 obtained in the first shooting scene, the subjects 11, 12, 15, and 16 are standing on the first floor area of the building, and the subjects 13, 14, 17, and 18 are the buildings. Standing in the 2nd floor area.

  FIG. 3 is a diagram showing a model of the positional relationship of subjects in the shooting scene shown in FIG.

  In the illustrated example, the subjects 11 to 18 are approximated by black spheres having a diameter w1. Each of the subjects 11 to 18 is positioned at the apex of a cube having a side length of d1, and the illustrated cube is imaged by an imaging device (hereinafter simply referred to as a camera) 19.

  FIG. 4 is a diagram illustrating a state in which all the subjects are focused by normal photographing with respect to the subject arrangement illustrated in FIG. 3.

  In normal shooting (second shooting mode), the center 20 of the in-focus plane is the midpoint of the side defined by the subjects 11 and 12, the subjects 13 and 14, the subjects 15 and 16, and the subjects 17 and 18 respectively. Set to a plane that passes through the midpoint of the specified side. At this time, the depth of field L1 necessary for keeping all the subjects in the in-focus range is L1 = d1 + w1.

  FIG. 5 is a diagram illustrating a state in which all the subjects are focused by tilt shooting with respect to the arrangement of the subjects illustrated in FIG. 3.

  In tilt shooting (first shooting mode), the focal plane center 21 is set to a plane that passes through the subjects 11, 14, 15, and 18. At this time, the depth of field L2 necessary for keeping all the subjects in the in-focus range is L2 = √2 × d1 + w1.

  Comparing the depths of field L1 and L2, since the depth of field L1 is smaller than the subject depth L2, normal shooting may be performed with a smaller F-number (aperture value) in the first shooting scene. it can.

  In the illustrated example, a special situation is assumed to explain the difference between normal photography and tilt photography, but there are various similar situations in actual photography scenes. This is also true for the second shooting scene described later.

  FIG. 6 is a diagram illustrating an example of an image obtained in the second shooting scene.

  In the image 10 obtained in the second shooting scene, the subjects 11 to 16 are standing in the first floor area of the building. These subjects 11 to 16 are arranged in a line in the depth direction of the screen.

  FIG. 7 is a diagram showing a model of the positional relationship of subjects in the shooting scene shown in FIG.

  Here, the subjects 11 to 16 are approximated by a circle having a diameter w1. The subjects 11 to 16 are arranged at a fixed distance d3.

  FIG. 8 is a diagram showing the positional relationship between the center of the focal plane and the subject at the time of normal shooting in the subject arrangement shown in FIG.

  As shown in the figure, the center 23 of the in-focus plane is located between the subjects 13 and 14, and the depth of field d4 required to bring all the subjects into the focus range at this time is d4 = 5 × d3 + w1.

  FIG. 9 is a diagram showing a state in which all the subjects are focused by tilt shooting with respect to the subject arrangement shown in FIG.

  Here, the center 24 of the focal plane includes a straight line connecting the centers of the subjects 11 to 16. The depth of field d5 necessary for keeping all subjects within the in-focus range is d5 = w1. Comparing the depths of field d4 and d5, the depth of field d5 <the subject depth d4. Therefore, in the second shooting scene, the tilt shooting can be performed with a smaller F value.

  As described above, which of normal shooting and tilt shooting can focus on all subjects with a smaller F-number varies depending on the arrangement state of the subjects.

[First Embodiment]
FIG. 10 is a block diagram showing the configuration of an example of the camera according to the first embodiment of the present invention.

  The camera 100 includes an imaging optical system 101 having a tilt mechanism, and an optical image (subject image) is formed on an imaging element 102 such as a CCD, CMOS sensor, or InGaAs sensor via the imaging optical system 101. . The imaging optical system control unit 111 performs focusing control, tilt control, exposure control, and the like of the imaging optical system 101 under the control of the system controller 112.

  The image sensor 102 outputs an image signal (analog signal) corresponding to the optical image. The image processing unit 103 A / D converts the image signal into a digital image signal. The image processing unit 103 performs predetermined image processing such as gamma correction and color balance adjustment on the digital image signal to generate image data such as JPEG.

  Image data that is an output of the image processing unit 103 is sent to the subject detection unit 104 and the system controller 112. Then, the system controller 112 displays the image data on the display unit 113 as a video.

  The subject detection unit 104 detects the subject by analyzing the image data. Then, the subject detection unit 104 sends the image data together with the subject detection result to the subject coordinate calculation unit 105. The subject coordinate calculation unit 105 holds the vertical and horizontal dimensions, the pixel pitch dimension, and the allowable confusion circle diameter of the image sensor 102 in advance, and also holds focal length information indicating the focal length of the imaging optical system 101.

  The subject coordinate calculation unit 105 first uses the subject detection result and the image data to generate subject information indicating the position of the subject on the image. Then, the subject coordinate calculation unit 105 sends the subject information to the system controller 112.

  The system controller 112 controls the distance measuring unit 110 based on the subject information to measure each subject. Then, the distance measurement unit 110 sends a distance measurement result obtained by measuring the subject to the subject coordinate calculation unit 105. The subject coordinate calculation unit 105 obtains a three-dimensional coordinate for each subject with reference to the distance measurement result. The subject coordinate calculation unit 105 sends the three-dimensional coordinates together with the image data to the tilt shooting focus plane calculation unit 106 and the normal shooting depth of field calculation unit 108.

  The tilting focus plane calculation unit 106 obtains a plane expression indicating a focus plane necessary for tilt tilting based on the three-dimensional coordinates of the subject. Then, the tilt shooting focus plane calculation unit 10 sends the plane expression indicating the focus plane and the three-dimensional coordinates of the subject to the tilt shooting depth of field calculation unit 107. A tilt shooting depth-of-field calculating unit 107 is an F value (hereinafter referred to as a tilt shooting F value) necessary for focusing all subjects based on a plane expression indicating a focal plane and the three-dimensional coordinates of the subject. )

  In the tilt shooting, which is the first shooting mode, tilt control is performed to control the angle (tilt angle) formed between the lens main surface of the imaging optical system 101 and the imaging plane formed by the imaging optical system 101. Shooting is performed. Note that the angle formed between the optical axis of the image sensor 102 and the imaging plane is also changed by controlling the angle formed between the lens main surface and the imaging plane. The imaging plane is formed on the image sensor 102.

  On the other hand, the normal shooting depth-of-field calculating unit 108 calculates an F value (hereinafter referred to as a normal shooting F value) necessary for focusing all subjects when performing normal shooting based on the three-dimensional coordinates of the subject. Ask. Then, the tilt shooting depth-of-field calculation unit 107 and the normal shooting depth of field calculation unit 108 send the tilt shooting F value and the normal shooting F value to the shooting mode selection unit 109, respectively.

  Note that in normal shooting, which is the second shooting mode, shooting is performed in a state where the lens main surface of the imaging optical system 101 and the imaging plane formed by the imaging optical system 101 are orthogonal to each other.

  The shooting mode selection unit 109 compares the tilt shooting F value and the normal shooting F value, and selects the smaller F value as the selected F value (selected aperture value). Then, the shooting mode selection unit 109 selects a shooting mode corresponding to the selected F value and sends it to the system controller 112 as the selected shooting mode. The system controller 112 controls the imaging optical system control unit 111 to drive the imaging optical system 101 based on the selected shooting mode.

  FIG. 11 is a flowchart for explaining an example of a photographing process performed by the camera shown in FIG. Note that the processing according to the illustrated flowchart is performed under the control of the system controller 112.

  When the photographing process is started, the system controller 112 determines whether or not a subject is detected by the subject detection unit 104 (step S2). If no subject is detected in the image (NO in step S2), system controller 112 stands by. On the other hand, when a subject is detected in the image (YES in step S2), the system controller 112 controls the distance measuring unit 110 to perform distance measurement on all detected subjects (step S3).

  Subsequently, under the control of the system controller 112, the subject coordinate calculation unit 105 calculates the actual subject position according to the apparent position of the subject on the image (screen) (step S4).

  12 is a diagram illustrating an example of an apparent position (apparent coordinate) set by the subject coordinate calculation unit illustrated in FIG.

  The captured image shown in FIG. 12 includes a plurality of subjects 301 to 304. When calculating the subject positions of the subjects 301 to 304 from the apparent positions of the subjects 301 to 304, the subject coordinate calculation unit 105 sets the X axis in the horizontal direction and the Y axis in the vertical direction with the center of the captured image 300 as the origin. . The unit of the X axis and the Y axis is the number of pixels.

  The subject coordinate calculation unit 105 assigns coordinates (X1, Y1), (X2, Y2), (X3, Y3), and (X4, Y4) to the subjects 301 to 303 in the XY coordinates. Hereinafter, these coordinates are called apparent coordinates on the image.

  FIG. 13 is a diagram illustrating an example of z-axis coordinates set by the subject coordinate calculation unit illustrated in FIG. 1.

  The subject coordinate calculation unit 105 assigns the distance measurement values obtained by the distance measurement unit 110 to the subjects 301 to 304 as Z coordinates Z1, Z2, Z3, and Z4, respectively. Then, the subject coordinate calculation unit 105 calculates a subject position (subject coordinate) that is an actual coordinate of the subject from the apparent XY coordinates of the subjects 301 to 304 using the Z coordinate.

  Here, an example of subject position calculation will be described using the subject 301 as an example.

  First, the subject coordinate calculation unit 105 multiplies the apparent XY coordinates on the screen (that is, the image) by the pixel pitch of the image sensor 102 to calculate coordinates on the image sensor surface. When the pixel pitch is p (mm), the actual coordinates of the subject on the image sensor surface are (Xp, Xp). This coordinate is in mm.

  Subsequently, the subject coordinate calculation unit 105 determines the subject 301 based on the focal length f (mm) of the imaging optical system 101 (lens) and the vertical dimension V (mm) and horizontal dimension H (mm) of the imaging element 102. The XY coordinates (X1, Y1) in the real space are obtained by the following expressions (1) and (2).

  As a result, the three-dimensional coordinates in the real space of the subject 301 are (X1, Y1, Z1). Similarly, when the three-dimensional coordinates in the real space are obtained for the subjects 302 to 304, they become (X2, Y2, Z2), (X3, Y3, Z3), and (X4, Y4, Z4), respectively.

  Referring to FIG. 11 again, after the calculation of the subject position, under the control of the system controller 112, the in-focus shooting focus plane calculation unit 106 obtains the in-focus plane for the tilt shooting (step S5). For example, the least square approximation is used when obtaining the in-focus plane in the tilt shooting.

  Here, the three-dimensional coordinates (X1, Y1, Z1) to (X4, Y4, Z4) in the real space of the subjects 301 to 304 are regarded as point sequences, and the in-focus photographing focal plane calculation unit 106 performs these operations. A plane is obtained by approximating the point sequence by least squares in the distance in the z-axis direction.

  First, the tilting-focusing-plane calculating unit 106 sets the equation of the approximate plane as equation (3).

  When the distance in the Z direction is considered, the distance di between the point (Xi, Yi, Zi) (where i = 1 to 4) and the plane indicated by the expression (3) is expressed by the following expression (4). The

  Then, considering the sum of squares Ω of the distances between all point sequences and the plane, the sum of squares Ω is expressed by the following equation (5).

  In order to obtain the coefficients a, b, and c for minimizing the equation (5), the tilting focus surface calculation unit 106 calculates the equation (5) for each of the counts a, b, and c. Partial differentiation is performed as shown in (6) to (8).

Where As = ΣX _i ² , Bs = ΣY _i ² , Cs = ΣX _i Y _i , Ds = ΣX _i z _i , Es = ΣY _i z _i , Fs = ΣX _i , Gs = ΣY _i , and Hs = Σz _{If i} is set, Formula (6)-Formula (8) will be represented by Formula (9)-Formula (10), respectively.

  If the simultaneous equations shown by the equations (9) to (11) are solved, the coefficients a, b, and c are expressed by the equations (12) to (14), respectively.

  Then, by substituting Equations (12) to (14) into Equation (3), a plane equation of the least square approximation plane can be obtained. This least square approximation plane is a plane expression of a focal plane in tilt shooting. Thereafter, z = ax + by + c is used as a plane expression of the in-focus plane in tilt shooting.

  Next, the in-focus photographing focal plane calculation unit 106 calculates a plane formula on which the lens principal plane necessary for obtaining the focal plane z = ax + by + c is to be arranged.

  FIG. 14 is a diagram illustrating an arrangement relationship between the imaging element illustrated in FIG. 1, a lens, and a focusing surface.

  The illustrated focal plane 300 is a focal plane obtained by the above-described formulas (3) and (12) to (14). A lens that is the imaging optical system 101 is arranged on the Z axis that is separated from the imaging element 102 by the focal length f. The imaging element plane is a plane with z = 0, and the public line with the plane formula of the focusing plane can be obtained by the following formula (15).

  When the intersection point E1 with the X-axis and the intersection point E2 with the Y-axis are taken as two points on the public line shown by the equation (15), the coordinates are E1 = (− c / a, 0, 0), E2 = (0 , −c / b, 0). Further, the coordinates of the center point E3 of the lens are E3 = (0, 0, f), and a plane passing through these three points corresponds to a plane expression of the lens main surface necessary for obtaining a desired focal plane. By generating vectors K1 = (c / a, −c / b, 0) and K2 = (c / a, 0, f) on the plane from the three points of coordinates E1 to E3, and taking these outer products As shown in Expression (16), a normal vector with respect to the plane of the lens principal surface is calculated.

  Further, a plane expression having a normal vector of the expression (16) through the point E3 is given by the following expression (17).

  Further, if the tilt control of the lens is performed so that the plane given by the above equation (18) and the lens main surface coincide with each other, a desired focal plane z = ax + by + c in tilt shooting can be obtained from the above-mentioned Shine-Pruff's law. It is done.

  Referring to FIG. 11 again, under the control of the system controller 112, the tilt shooting depth-of-field calculating unit 107 calculates an F value necessary for focusing on all subjects in tilt shooting (step S6). . Here, first, the tilt shooting depth-of-field calculating unit 107 calculates the distance between the subjects 301 to 304 and the focal plane z = ax + by + c in tilt shooting using the following equation (19).

However, i = 1 to 4.

  The tilt shooting depth-of-field calculating unit 107 calculates the sum Sm of the absolute value of the positive maximum value and the negative minimum value in the distance from the focal plane. This sum Sm is the depth of field necessary to bring all the subjects 301 to 304 into the in-focus range.

  Next, the tilt shooting depth-of-field calculating unit 107 calculates an F value at which the depth of field is the sum Sm. The depth of field T is obtained by adding the front depth of field Tf and the rear depth of field Tr. Let R be the permissible circle of confusion and F be the aperture value of the lens. Furthermore, if the distance from the center of the image sensor surface to the focal plane in tilt shooting is Zv, the depth of field T can be obtained by the following equation (20). However, Zv is given by equation (21).

  Then, the tilt depth-of-field calculating unit 107 calculates the F when the depth of field T shown in the equation (20) is equal to the aforementioned sum (required depth of field) Sm by the following equation (21). Calculate the value.

  When equation (22) is solved with respect to the F value, as shown by equation (23), the F value necessary for keeping all subjects in the in-focus range in tilt shooting can be calculated.

  Subsequently, under the control of the system controller 122, the normal shooting depth-of-field calculating unit 108 calculates an F value necessary for focusing on all subjects when using normal shooting (step S7). As described above, the distance information obtained by the distance measuring unit 110 is assigned to each of the subjects 301 to 304 as the z coordinate. The Z coordinates are Z1, Z2, Z3, and Z4, respectively.

  The normal shooting depth-of-field calculating unit 108 selects the maximum value Zmax and the minimum value Zmin among these Z coordinates Z1 to Z4, and calculates the difference (Zmax−Zmin). This difference (Zmax−Zmin) is the depth of field necessary for focusing on all subjects in normal shooting.

  Next, in the same manner as the method used in tilt shooting, the normal shooting depth-of-field calculating unit 108 calculates an F value necessary for the depth of field to be (Zmax−Zmin). The depth of field T at this time is obtained by adding the front depth of field Tf and the rear depth of field Tr. Assuming that the permissible circle of confusion is R, the aperture value of the lens is F, and the distance from the center of the image sensor surface to the focusing surface in normal shooting is Zv, the depth of field T is expressed by the following equation (24). can get. However, here, Zv is given by equation (25).

  When the F value is arranged, the F value in normal shooting (normal shooting F value) is obtained by the equation (26).

  The F value represented by Expression (26) is an F value necessary for focusing on all subjects in normal shooting.

  Subsequently, under the control of the system controller 112, the shooting mode selection unit 109 compares the tilt shooting F value and the normal shooting F value, and the mode that can be shot with the minimum F value based on the comparison result is the tilt shooting. It is determined whether or not (step S8). That is, the shooting mode selection unit 109 selects a shooting mode in which shooting can be performed with a smaller F value.

  If the mode selection result indicates tilt shooting (YES in step S8), the system controller 112 controls the imaging optical system control unit 111 to drive the imaging optical system 101 by tilt (TILT) (step S9). At this time, the system controller 112 performs tilt control so that the main surface of the lens becomes the in-focus surface obtained by the equations (3) and (12) to (14).

  Subsequently, the system controller 112 controls the imaging optical system control unit 111 to control the focusing of the imaging optical system 101 (step S10). Then, the system controller 112 executes tilt shooting. Thereafter, the system controller 112 returns to the process of step S2.

  On the other hand, if the mode selection result indicates normal shooting (NO in step S8), the system controller 112 proceeds to the process of step S10 and performs focus control of the imaging optical system 101. The system controller 112 executes normal shooting.

  As described above, in the first embodiment of the present invention, it is determined whether or not all subjects can be focused with a smaller F value in either the tilt shooting or the normal shooting. Since the photographing mode is switched based on the determination result, the subject can be photographed in the optimum photographing mode even if the state of the subject changes.

[Second Embodiment]
Next, an example of a camera according to the second embodiment of the present invention will be described.

  FIG. 15 is a block diagram showing the configuration of an example of a camera according to the second embodiment of the present invention. In FIG. 15, the same components as those of the camera shown in FIG.

  The illustrated camera 100 includes an image sensor control unit 114. The imaging element 102 includes a tilt mechanism, and the tilting mechanism can tilt the imaging element surface with respect to the imaging optical system 101. The image sensor control unit 114 performs tilt control of the image sensor 102 under the control of the system controller 112.

  FIG. 16 is a flowchart for explaining an example of a photographing process performed by the camera shown in FIG. In FIG. 16, the same steps as those in the flowchart shown in FIG. 11 are denoted by the same reference numerals, and the description thereof is omitted.

  If the mode selection result indicates tilt shooting (YES in step S8), the system controller 112 drives the image sensor 102 to tilt (tilt control) by the image sensor control unit 114 (step S11).

  Here, calculation of the drive amount for tilt control of the image sensor 102 will be described.

  First, the plane expression of the focal plane in tilt shooting is set to z = ax + by + c. In the second embodiment, the tilt control of the imaging optical system 101 is not performed, and as a result, the planar expression of the lens main surface is z = f. The public line between the lens main surface and the focusing surface z = ax + by + c is 0 = ax + by−f + c. The planar expression of the imaging surface of the image sensor 102 to be obtained includes the coordinates I1 (0, 0, 0) of the center of the image sensor including this public line.

  Considering the intersection point I2 between the X axis and the Y axis as two points on the public line 0 = ax + by−f + c, the intersection point I2 is ((f−c) / a, 0, f), and the intersection point I3 is ( 0, (f−c) / b, f). The system controller 112 generates a vector T1 using the intersection points I1 and I2, and generates a vector T2 using the intersection points I1 and I3. Then, the system controller 112 obtains the outer product of the vectors T1 and T2 by Expression (27), and calculates the normal vector of the plane of the imaging surface.

  A plane equation including the normal vector represented by the equation (27) and including the point I1 (0, 0, 0) is represented by the following equation (28).

  Rearranging equation (28) yields equation (29).

  The system controller 112 tilts the image sensor 102 so that the image sensor surface (imaging surface) coincides with the plane represented by Expression (29). Thereby, the in-focus plane z = ax + by + c in the tilt shooting can be obtained. Note that after the process of step S11, the system controller 112 proceeds to the process of step S10.

  As described above, in the second embodiment of the present invention, as in the first embodiment described above, even if the subject situation changes by switching the shooting mode based on the determination result, the SNR is good. Shooting can be performed in shooting mode. Furthermore, since the image pickup device that is smaller than the image pickup optical system is tilt-controlled, the camera can be downsized compared to the case where the image pickup optical system 101 is tilt-controlled.

[Third Embodiment]
Next, an example of a camera according to the third embodiment of the present invention will be described. The configuration of the camera according to the third embodiment is the same as that of the camera shown in FIG.

  FIG. 17 is a block diagram showing a configuration of a subject detection unit used in a camera according to the third embodiment of the present invention.

  The illustrated subject detection unit 104 includes a moving body detection unit 114 and a face detection unit 115. Then, image data is sent from the image processing unit 103 to the moving object detection unit 114 and the face detection unit 115. The moving object detection unit 114 analyzes the image data, detects a moving object that is a moving subject, and outputs the moving object detection result to the subject coordinate calculation unit 105. The face detection unit 115 analyzes the image data, detects the face area (specific area) of the person who is the subject, and outputs the face detection result to the subject coordinate calculation unit 105.

  The subject coordinate calculation unit 105 determines a subject to be focused and a subject not to be focused using the moving object detection result and the face detection result. Here, the subject coordinate calculation unit 105 detects a moving object, but determines that a subject whose face is not detected is out of focus. In this way, by selecting the subject to be focused, the number of focused targets is reduced, so that the possibility that the depth of field can be made shallower than when all the subjects are focused is increased. As a result, photographing can be performed with a smaller F value.

  FIG. 18 is a flowchart for explaining a photographing process performed by the camera according to the third embodiment of the present invention. In FIG. 18, the same steps as those in the flowchart shown in FIG. 11 or FIG.

  When the photographing process is started, the subject detection unit 104 detects a moving object under the control of the system controller 112. Then, the system controller 112 determines whether or not a moving object is detected by the subject detection unit 104 (step S12). If no moving object is detected (NO in step S12), system controller 112 stands by.

  When a moving object is detected (YES in step S12), the subject detection unit 104 performs face detection on the moving object under the control of the system controller 112. Then, the system controller 112 determines whether or not a face is detected by the subject detection unit 104 (step S13). If no face is detected (NO in step S13), system controller 112 returns to the process in step S12.

  On the other hand, when a face is detected (YES in step S13), the system controller 112 performs distance measurement on the moving object (subject) from which the face is detected by the distance measuring unit 110 (step S14). Thereafter, the system controller 112 proceeds to the process of step S4.

  As described above, in the third embodiment of the present invention, a moving object, that is, the face of a person acting is detected, and imaging processing is performed while paying attention to the person. That is, only a subject that is desired to be noticed when performing suspicious person monitoring or abnormal behavior monitoring is set as a focusing target, and a subject that is not important for monitoring, such as a moving object other than a person, is excluded from focusing. As a result, the required focus width can be further reduced. As a result, the required F value can be further reduced, and an image with a good SNR can be obtained.

[Fourth Embodiment]
Next, an example of a camera according to the fourth embodiment of the present invention will be described.

  FIG. 19 is a block diagram showing the configuration of an example of a camera according to the fourth embodiment of the present invention. In FIG. 19, the same reference numerals are assigned to the same components as those of the camera shown in FIG.

  In the camera shown in FIG. 19, the imaging subject coordinate calculation unit 105, the display unit 113, and the system controller 112 are connected bidirectionally. As described above, the system controller 112 displays an image corresponding to the image data on the display unit 113. The user visually observes the image displayed on the display unit 113, and selectively designates a three-dimensional range to be masked from the in-focus object in the image by an operation unit (not shown) as a mask range.

  When the user designates a mask range, information indicating the mask range is sent from the display unit 113 to the system controller 112. Then, the system controller 112 sends the mask range information to the subject coordinate calculation unit 105. As will be described later, the subject coordinate calculation unit 105 obtains subject coordinates excluding the mask range defined by the mask range information.

  FIG. 20 is a flowchart for explaining a photographing process performed by the camera shown in FIG. In FIG. 20, the same steps as those in the flowcharts shown in FIGS. 11 and 16 are denoted by the same reference numerals, and the description thereof is omitted.

  When the photographing process is started, as described above, the user sets a mask range as necessary (step S15).

  FIG. 21 is a diagram showing an example of a mask range set in the image displayed on the display unit shown in FIG.

  In the example shown in the figure, it is assumed that the user has set the three-dimensional mask range 20 so as not to be focused. As a result, the subject 16 is not focused. Then, the system controller 112 sends mask range information (mask range coordinates) indicating the three-dimensional mask range 20 to the subject coordinate calculation unit 105.

  Subsequently, the system controller 112 determines whether or not a subject is detected by the subject detection unit 104 in step S2. After the process of step S4, under the control of the system controller 112, the subject coordinate calculation unit 105 determines whether or not the detected subject exists in the mask range (also referred to as a mask region) (step S16).

  If the subject exists in the mask range (YES in step S16), system controller 112 returns to the process in step S2. On the other hand, if the subject does not exist in the mask range (NO in step S16), the system controller 112 proceeds to the process in step S5, and the focus plane for tilt shooting is obtained by the tilt shooting focus plane calculation unit 106. .

  In the fourth embodiment, the image pickup element is tilt-controlled in step S11. However, the image pickup optical system 101 may be tilt-controlled. At this time, the image sensor control unit 114 shown in FIG. 19 is not necessary.

  As described above, in the fourth embodiment of the present invention, in the case where an image, that is, a range shot by another camera exists in the shooting range, an unnecessary subject can be combined if the user masks the range. It can be removed from the focus object. As a result, the possibility that the F value required for focusing can be further reduced can be increased.

  As described above, in the embodiment of the present invention, it is possible to automatically select a shooting mode having a good SNR in shooting in a dark place or the like regardless of the state of the subject.

  As is clear from the above description, in the example shown in FIG. 10, the system controller 112 and the shooting mode selection unit 109 function as selection means, and the system controller 112, the subject coordinate calculation unit 105, and the in-focus shooting focus plane calculation unit. 106 and the tilt shooting depth-of-field calculating unit 107 function as first calculating means. Further, the system controller 112, the subject coordinate calculation unit 105, and the normal shooting depth of field calculation unit 108 function as a second calculation unit. The distance measuring unit 110 and the system controller 112 function as distance measuring means, and the system controller 112 and the imaging optical system control unit 111 function as control means.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the function of the above embodiment may be used as a control method, and this control method may be executed by the imaging apparatus. Further, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the imaging apparatus. The control program is recorded on a computer-readable recording medium, for example.

[Other Embodiments]
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 104 Subject detection part 105 Subject coordinate calculation part 106 Focusing plane calculation part for tilt shooting 107 Depth of field calculation part for tilt shooting 108 Depth of field calculation part for normal photography 109 Shooting mode selection part 110 Distance measuring part 111 Imaging optics System control unit 112 System controller 114 Image sensor control unit

Claims (10)

An imaging device that includes an imaging device on which an optical image is formed via an imaging optical system, and obtains an image according to the output of the imaging device,
The first imaging mode for performing imaging by performing tilt control for controlling the angle between the lens main surface of the imaging optical system and the imaging plane, and the lens main surface of the imaging optical system and the imaging plane are orthogonal to each other Selecting means for selecting one of the second shooting modes for shooting in a state;
Ranging means for obtaining distance information by measuring the distance from the imaging device to a subject existing in the shooting range of the image;
First calculating means for obtaining a tilt angle and a first aperture value for focusing on a plurality of subjects existing in the shooting range in the first shooting mode;
Second calculating means for determining a second aperture value for focusing on a plurality of subjects existing in the shooting range in the second shooting mode;
The selection unit selects either the first shooting mode or the second shooting mode as a selected shooting mode based on a comparison result between the first aperture value and the second aperture value. An imaging device.   The selection unit compares the first aperture value and the second aperture value, and selects a shooting mode corresponding to a smaller aperture value as the selected shooting mode. The imaging device according to claim 1.   The first calculation means obtains an angle of the imaging surface with respect to the lens main surface for focusing all of the subjects existing in the imaging range on the imaging surface when obtaining the tilt angle, The imaging apparatus according to claim 1, wherein the tilt angle is obtained according to the angle.   4. The apparatus according to claim 1, further comprising a control unit configured to control the tilt of at least one of the image pickup optical system and the image pickup device to obtain the tilt angle when shooting is performed in the first shooting mode. 5. The imaging apparatus of Claim 1.   The imaging apparatus according to claim 1, further comprising a detection unit configured to detect a subject in the imaging range. The detecting means detects whether or not the subject is a moving object and detects whether or not a predetermined specific area exists in the subject when detecting the subject.
6. The distance measuring unit according to claim 5, wherein the distance measuring unit measures a distance to the subject when the detecting unit detects that the subject is a moving object and the specific area exists. Imaging device.   The imaging apparatus according to claim 6, wherein the specific area is a human face area. Mask means for selectively masking a subject existing in the imaging range of the image;
8. The method according to claim 1, wherein each of the first calculation unit and the second calculation unit excludes the subject masked by the mask unit from being focused. Imaging device. An imaging device control method comprising an imaging device on which an optical image is formed via an imaging optical system, and obtaining an image according to the output of the imaging device,
The first imaging mode for performing imaging by performing tilt control for controlling the angle between the lens main surface of the imaging optical system and the imaging plane, and the lens main surface of the imaging optical system and the imaging plane are orthogonal to each other A selection step for selecting one of the second shooting modes for shooting in a state;
A distance measuring step for measuring distance from the imaging device to a subject existing in the imaging range of the image to obtain distance information;
A first calculation step for obtaining a tilt angle and a first aperture value for focusing on a plurality of subjects existing in the shooting range in the first shooting mode;
A second calculation step of obtaining a second aperture value for focusing on a plurality of subjects existing in the shooting range in the second shooting mode;
In the selection step, either the first shooting mode or the second shooting mode is selected as a selected shooting mode based on a comparison result between the first aperture value and the second aperture value. Control method. A control program used in an imaging apparatus that includes an imaging element on which an optical image is formed via an imaging optical system and obtains an image according to an output of the imaging element,
In the computer provided in the imaging device,
The first imaging mode for performing imaging by performing tilt control for controlling the angle between the lens main surface of the imaging optical system and the imaging plane, and the lens main surface of the imaging optical system and the imaging plane are orthogonal to each other A selection step for selecting one of the second shooting modes for shooting in a state;
A distance measuring step for measuring distance from the imaging device to a subject existing in the imaging range of the image to obtain distance information;
A first calculation step for obtaining a tilt angle and a first aperture value for focusing on a plurality of subjects existing in the shooting range in the first shooting mode;
Executing a second calculation step for obtaining a second aperture value for focusing on a plurality of subjects existing in the shooting range in the second shooting mode;
In the selection step, either the first shooting mode or the second shooting mode is selected as a selected shooting mode based on a comparison result between the first aperture value and the second aperture value. Control program.