JP2006128995A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus correcting exaggerated depth perception in camera movement photographing attended with tilt camera movements. <P>SOLUTION: The imaging apparatus includes: a lens; an imaging device with an imaging face for imaging an optical image resulting from an object image projected via the lens; and a control section for correcting the exaggerated depth perception by swing or tilt camera movements on the basis of a photographing magnification for each position on the imaging face as to a first image imaged and obtained by the imaging element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tilt photographing apparatus, and more particularly to a device that corrects an exaggerated perspective due to a tilt tilt.

  Conventionally, tilting tilting and tilting tilting (which collectively refers to tilt tilting) in which the optical axis of the lens intersects with the imaging surface perpendicularly and the lens is tilted with respect to the imaging surface have been proposed. ing.

  However, in the tilt tilt, the perspective of the subject is exaggerated because the shooting magnification on the imaging surface is not constant. When the tilt operation is performed by combining the tilt tilt and the parallel tilt, the exaggeration of perspective can be made inconspicuous, but experience and advanced skill are required to set an appropriate tilt amount.

  Accordingly, an object of the present invention is to provide an imaging device that corrects an exaggerated perspective in tilt shooting with tilt tilt.

  An imaging apparatus according to the present invention includes a lens, an imaging element having an imaging surface that captures an optical image obtained by projecting a subject image through the lens, and a first image obtained by imaging with the imaging element. And a control unit that corrects the perspective exaggerated by swing or tilt tilt based on the photographing magnification for each upper position.

  Preferably, the photographing magnification is determined by the focal length of the lens, the image distance between the surface including the second principal point of the lens at the time of focusing and perpendicular to the optical axis, and the tilt angle due to swing or tilt tilt. Based on.

  More preferably, a lens information reading unit that acquires information on a focal length, a focus information reading unit that detects a video distance based on position information of a focusing lens included in the lens, and an inclination angle reading unit that detects an inclination angle. Further prepare.

  Preferably, for each position on the imaging surface, the control unit enlarges or reduces the image area corresponding to the position of the imaging surface by the imaging magnification corresponding to the position of the imaging surface, thereby obtaining a rectangular shape. First image deformation means for deforming the first image into a second image having a substantially trapezoidal shape, and a third image obtained by extracting a rectangular area inside the second image and having the same aspect ratio as that of the first image And second image deformation means for obtaining the fourth image by expanding the third image to the same size as the first image.

  More preferably, the image processing apparatus further includes a display unit that displays a portion of the second image that is inside the first image and the third image as a through image.

  More preferably, enlargement by the photographing magnification is performed by pixel interpolation, and reduction by the photographing magnification is performed by pixel thinning.

  As described above, according to the present invention, it is possible to provide an imaging device that corrects an exaggerated perspective in tilt shooting with tilt tilt.

  Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a configuration diagram of the imaging apparatus 1. 2 and 3 show optical path diagrams before swinging in. FIG. 4 shows the optical path diagram after swing-in.

  The imaging apparatus 1 includes a tilt camera 10, a control unit 50, and a display unit 60 (see FIG. 1). In addition, in order to explain the direction, the optical axis LX in a state where no swing-in is performed in the imaging apparatus 1 (neutral state where the optical axis LX of the imaging lens 11 intersects the imaging surface 31a of the imaging element 31 perpendicularly) A horizontal direction orthogonal to the first direction x, a vertical direction orthogonal to the optical axis LX as a second direction y, and a horizontal direction parallel to the optical axis LX as a third direction z will be described.

  In the present embodiment, a line connecting the centers of curvature of the lens curved surfaces is defined as an optical axis LX.

  The first direction x is the upward direction in the state shown in FIG. 4 when the tilt shooting camera 10 is viewed from above, that is, the left direction when the tilt shooting camera 10 is viewed from the shooting lens 11 side is the positive direction. In the second direction y, the vertical upward direction is the positive direction. In the third direction z, the direction from the rear portion 30 to the front portion 20 is a positive direction. The tilt angle ω is a direction in which the left side of the imaging surface 31a of the rear portion 30 approaches the photographing lens 11 and the right side moves away from the photographing lens, that is, the clockwise direction in FIG.

  The tilting camera 10 is a camera capable of swinging tilt. The tilt shooting camera 10 includes a shooting lens 11, a front unit 20, a rear unit 30, a focus information reading unit 41, a lens information reading unit 42, and a tilt angle reading unit 44.

  In this embodiment, the exaggerated perspective correction operation in the case of the tilt tilt using the swing tilt operation will be described, but the same applies to the tilt tilt operation.

  The taking lens 11 is attached to the mount surface 21 of the front part 20. A photographing lens 11 having different specifications such as a focal length is prepared according to the photographing purpose.

  The taking lens 11 includes a ROM 11a and an encoder 11b in which lens specific data relating to the optical characteristics of the taking optical system is stored.

  When the photographic lens 11 is attached to the front portion 20, the first communication contact pin 11 c provided on the photographic lens 11 and the second communication contact pin 21 c provided on the lens mount portion 21 of the front portion 20 are used. The lens-specific data can be detected. The lens specific data is information relating to the focal length f, the maximum aperture value, the minimum aperture value, the current aperture value, the diameter of the image circle, the position of the first principal point H1 and the position of the second principal point H2 of the photographing lens. .

  The encoder 11b detects position information in the optical axis LX direction of the focusing lens incorporated in the photographing lens 11. When the photographic lens 11 is mounted on the front unit 20, the first lens and the second communication contact pins 11c and 21c are used to extend the subject lens from the position of the focusing lens when focusing on an object at infinity. The feed amount data corresponding to the amount can be detected.

  The rear unit 30 includes an image sensor 31 such as a CCD and an image signal processing circuit 32. An optical image obtained by projecting the subject image via the photographing lens 11 is formed on the imaging surface 31 a of the imaging element 31. The image sensor 31 converts an optical image into an electrical signal by photoelectric conversion. After being accumulated in the image sensor 31 for a certain period of time, an electrical signal based on the read electric charge is output to the image signal processing circuit 32. The imaging signal processing circuit 32 converts an electrical signal of a subject obtained by imaging with the tilt shooting camera 10 into an image signal that can be observed with the image processing and display unit 60 by the control unit 50 and outputs the image signal to the control unit 50. .

  The rear portion 30 can be rotated, i.e. swinged around an axis parallel to the second direction y.

  FIG. 2 shows an imaging surface 31a, a surface that includes the first principal point H1 and is orthogonal to the optical axis LX (hereinafter referred to as “first lens surface”), and a planar subject PS before performing swing-in. A parallel state (first state) is shown. A surface including the second principal point H2 and orthogonal to the optical axis LX is defined as a second lens surface.

  In the first state, the distance between the subject PS and the first lens surface (subject distance) does not change according to the position of the subject in the first direction x and does not change according to the position in the second direction y. Further, the distance (image distance) between the imaging surface 31a and the second lens surface does not change according to the position in the first direction x of the imaging surface 31a, and does not change according to the position in the second direction y. Accordingly, the image obtained by imaging the subject PS (first pre-tilt image bi1) has no perspective on the planar subject (see FIGS. 2 and 5).

  That is, subjects having the same size on the plane including the subject PS are imaged to the same size without changing the size ratio. At that time, all the points on the plane including the subject PS are in focus.

  FIG. 3 shows a state where the imaging surface 31a and the lens surface are parallel to each other, but the planar subject PS and the lens surface are not parallel before performing swing-in. In the second state, the subject distance changes according to the position of the subject PS in the first direction x and does not change according to the position of the second direction y. The video distance does not change according to the position in the first direction x of the imaging surface 31a, and does not change according to the position in the second direction y. Therefore, the image (second pre-tilt image bi2) obtained by imaging the subject PS has a sense of perspective in the first direction x (see FIGS. 3 and 6).

  That is, a subject having the same size on the plane including the subject PS is picked up with the size changed based on the characteristics of the photographing lens 11. However, only the point Oa is focused, and the other points are not focused. In FIG. 6, the focused shape is indicated by a thick line, and the unfocused shape is indicated by a thin line.

  FIG. 4 shows a state in which the parallel state between the imaging surface 31a and the lens surface is broken and all of the subject PS is focused after performing swinging. In the third state, the subject distance changes according to the position of the subject PS in the first direction x and does not change according to the position of the second direction y. Further, the video distance changes according to the position in the first direction x of the imaging surface 31a, and does not change according to the position in the second direction y. Therefore, the image (first image i1) obtained by imaging the subject PS has a sense of perspective in the first direction x, and the perspective is particularly exaggerated compared to the second tilted image bi2 (FIG. 4). FIG. 7).

  That is, a subject having the same size on a plane including the subject PS is captured with a size exaggerated as compared with the second pre-tilt image bi2.

  The focus information reading unit 41 performs parallel tilt and swing tilt using predetermined table data (not shown) based on position information (focusing lens extension amount data) of the photographing lens 11 by the encoder 11b. The distance (image distance b0) between the center Ob of the imaging surface 31a and the surface that includes the second principal point H2 of the imaging lens 11 and is perpendicular to the optical axis LX is detected. The focus information reading unit 41 is always supplied with the value of the amount of extension of the focusing lens from the encoder 11b, and the corresponding video distance b0 is always output to the control unit 50.

  The lens information reading unit 42 detects lens specific data in the ROM 11 a of the photographic lens 11 and outputs it to the control unit 50.

  The tilt angle reading unit 44 is a rotation amount detection mechanism, and detects a deviation between the optical axis LX and the lens axis due to swing tilt, that is, the tilt angle ω, and outputs it to the control unit 50.

  The control unit 50 is a control unit that controls each unit related to imaging.

  Based on the focal length f, the tilt angle ω, and the image distance b0 at the center Ob of the image pickup surface 31a, the control unit 50 on the image pickup surface 31a that is separated from the center Ob by L in the first direction x. A video distance bL, a subject distance aL, an imaging magnification mL, and an enlargement / reduction ratio ZL at an arbitrary point Pb are calculated. The subject distance aL is a distance between a point Pa on the subject corresponding to an arbitrary point Pb on the imaging surface 31a and a surface (lens surface) that includes the first principal point H1 of the photographing lens 11 and is perpendicular to the optical axis LX. . FIG. 4 shows a state in which an arbitrary point Pb is at the upper end (left end when the tilting camera 10 is viewed from the photographing lens 11 side) on the imaging surface 31a corresponding to the lower end (left end when viewed from the tilting camera 10) of the subject PS. Indicates.

  A first distance d0 and a second distance dL used in the process of calculating the image distance bL, the subject distance aL, the photographing magnification mL, and the enlargement / reduction ratio ZL are defined (see FIG. 4). On the xz plane perpendicular to the second direction y, the first line L1 including the subject PS after swing-in, the second line L2 including the lens surface of the photographing lens 11, and the third line L3 including the imaging surface 31a. A distance in the first direction x between the intersection point Q and the point Ob is a first distance d0, and a distance in the first direction x between the intersection point Q and the point Pb is a second distance dL. Accordingly, the second distance dL is equal to the length obtained by adding the arbitrary distance L to the first distance d0 (dL = d0 + L). When the first to third lines L1 to L3 intersect at one point (intersection point Q), the entire surface of the subject PS after swinging is in focus (Scheinpf's law). The angle formed by the second line L2 and the third line L3 is equal to the tilt angle ω.

  The first distance d0 is obtained by d0 = b0 ÷ tanω. The video distance bL is obtained by bL = dL × tan ω = (d0 + L) × tan ω. The subject distance aL is obtained by aL = (f × bL) ÷ (bL−f). The photographing magnification mL is obtained as mL = bL ÷ aL. The photographing magnification of the point Ob is defined as m0. The enlargement / reduction ratio ZL is a ratio with the photographing magnification at the screen center point Ob, and is obtained by ZL = mL / m0. The first to third distribution tables TA1 to TA3 are created by changing the value of L and performing these calculations in the region on the imaging surface 31a.

  The first distribution table TA1 shows the distribution state of the imaging magnification mL (= m0) for each cell in the area on the imaging surface 31a divided in a lattice shape before swing-in (see FIG. 8). The size of one cell is equal to a rectangular shape in which a plurality of pixels constituting the image sensor 31 are arranged. As the size of one cell is set smaller, it becomes possible to obtain the distribution of the photographing magnification and the enlargement / reduction ratio in detail.

  Before the swinging orientation, the imaging magnification mL of all the cells is m0. In the present embodiment, as shown in FIG. 8, the first distribution table TA1 is divided into 7 columns in the first direction x and 5 rows in the second direction y, and 35 cells (m011 to m017, m021 to m027). M031 to m037, m041 to m047, m051 to m057).

  The second distribution table TA2 shows a distribution state of the imaging magnification mL for each cell in the area on the imaging surface 31a divided in a lattice shape after swinging (see FIG. 9). The imaging magnification mL for each cell is calculated by the value of L changed so as to correspond to the cell position and the above calculation. In the present embodiment, as shown in FIG. 9, the second distribution table TA2 is divided into seven columns in the first direction x and five rows in the second direction y according to the number of lattices of the first distribution table. Cells (mL11-mL17, mL21-mL27, mL31-mL37, mL41-mL47, mL51-mL57).

  The third distribution table TA3 shows a distribution state of the enlargement / reduction ratio ZL for each cell in the region on the imaging surface 31a divided in a lattice shape after swing-in (see FIG. 10). The enlargement / reduction ratio ZL for each cell is calculated by the first and second distribution tables TA1, TA2 and the above calculation. The third distribution table TA3 makes it possible to know the enlargement / reduction ratio distribution due to the difference in photographing magnification on the image pickup surface 31a when performing swing-in.

  In the present embodiment, as shown in FIG. 10, the third distribution table TA3 includes seven columns in the first direction x and five in the second direction y according to the number of lattices of the first and second distribution tables TA1 and TA2. It is divided into rows and has 35 cells (ZL11 to ZL17, ZL21 to ZL27, ZL31 to ZL37, ZL41 to ZL47, ZL51 to ZL57). As the number of cells increases, it becomes possible to form a distribution of the enlargement / reduction ratio finely.

  When swinging is performed, the value of the video distance bL changes when the position is displaced in the first direction x, but does not change even if the position is displaced in the second direction y. Therefore, the values of the enlargement / reduction ratio ZL of the cells in five rows (for example, ZL11, ZL21, ZL31, ZL41, ZL51) in the same column are equal.

  The control unit 50 performs perspective correction based on the third distribution table TA3 on the image signal obtained by imaging in a state where the tilt is performed.

  Specifically, the image obtained by imaging (see the first image i1, see FIG. 11) is enlarged by an enlargement / reduction ratio ZL for each area of the imaging surface 31a corresponding to 35 cells partitioned in a grid pattern ( Pixel interpolation) or reduction (pixel thinning). For an image deformed into a substantially trapezoidal shape by enlargement and reduction (second image i2, see FIGS. 11 and 12), only a certain rectangular region inside the substantially trapezoidal shape is extracted. The extracted image (third image i3, see FIG. 12, FIG. 14) is enlarged to the same size as the first image i1, and is used as a corrected image (fourth image i4, see FIG. 13, FIG. 15).

  The constant rectangular area inside the substantially trapezoidal shape is desirably set as large as possible within the range of the outer shape of the second image i2 with the same aspect ratio as the rectangle constituting the outer frame i1 'of the first image.

  As a result, it is possible to obtain an image in which an exaggerated perspective is corrected in consideration of a difference in photographing magnification when tilting is performed. FIGS. 11 to 13 show the state of an image corresponding to an actually captured subject, and FIGS. 14 and 15 show the state of a cell to be subjected to enlargement / reduction calculation. 11 to 15, the first image i1 is indicated by a solid line, the second image i2 is indicated by a two-dot chain line, the third image i3 is indicated by a broken line, and the fourth image i4 is indicated by a solid line. 12 and 14, the outer frame i1 'of the first image i1 is also shown. FIG. 13 also shows an outer frame i2 'of the second image that is enlarged as the third image i3 is enlarged. FIG. 15 also shows a cell (outer frame i2 ') of the second image i2 that is enlarged as the third image i3 is enlarged.

  Next, an operation procedure for performing exaggerated perspective correction by swing-aori will be described with reference to the flowchart of FIG.

  When the power of the imaging apparatus 1 is turned on, lens specific data including the focal length f is output to the control unit 50 by the lens information reading unit 42 in step S31.

  In step S32, the focusing lens of the photographic lens 11 is moved to perform a focusing operation.

  In step S <b> 33, the video information b <b> 0 is detected by the focus information reading unit 41 and output to the control unit 50. In step S34, the first distribution table TA1 is created. In step S35, the swinging operation is performed by rotating the rear portion 30 about an axis parallel to the second direction y. In step S <b> 36, the swing angle tilt angle ω is detected by the tilt angle reading unit 44 and output to the control unit 50.

  In step S37, a second distribution table TA2 is created, and a third distribution table TA3 is created based on the first and second distribution tables TA1 and TA2. The third distribution table TA3 is temporarily stored in the control unit 50 or a storage unit connected to the control unit 50.

  In step S38, it is determined whether or not a photographing operation has been performed. If the photographing operation is not performed, the process returns to step S32.

  When the photographing operation is performed, the temporarily stored third distribution table TA3 is read out in step S39. In step S40, perspective correction is performed based on the third distribution table TA3. In step S41, preview images after the perspective correction (outer frame i1 ′ of the first image, second image i2, outer frame of the third image i3, see FIG. 12) are generated, and in step S42, these are displayed on the display unit. 60 (preview image).

  Only the inner part of the outer frame i1 'of the first image is displayed on the display unit 60 as a preview image in FIG. In FIG. 12, the hatched portion that rises to the right is an area that has been reduced when the second image i2 is generated and data has been lost. The left-upward hatched area is an area that is enlarged when the second image i2 is generated and does not appear as a preview image that protrudes from the display area.

  In step S43, an image displayed inside the outer frame of the third image i3 is confirmed from the preview image, and it is determined whether or not the image should be recorded. If it is determined that the image should not be recorded, the process returns to step S32.

  If it is determined that the image should be recorded, a recorded image (fourth image i4) after perspective correction is generated in step S44, and an image signal corresponding to the fourth image i4 is recorded in step S45. The perspective correction process ends.

It is a block diagram of the imaging device in this embodiment. It is an optical path figure of the tilt photography camera in the 1st state. It is an optical path figure of the tilt photography camera in the 2nd state. It is an optical path figure of the tilt photography camera in the 3rd state. It is a figure which shows the 1st pre-tilt image obtained by imaging the to-be-photographed object in a 1st state. It is a figure which shows the 2nd pre-tilt image obtained by imaging the to-be-photographed object in a 2nd state. It is a figure which shows the 1st image obtained by imaging a to-be-photographed object in a 3rd state. It is a figure which shows a 1st distribution table. It is a figure which shows a 2nd distribution table. It is a figure which shows a 3rd distribution table. It is a figure which shows the 1st, 2nd image corresponding to the imaged to-be-photographed object. It is a figure which shows the outer frame of the 1st image corresponding to the imaged subject, the 2nd image, and the outer frame of the 3rd image. It is a figure which shows the 4th image corresponding to the imaged subject. It is a figure which shows the cell expanded and reduced with the production | generation of a 2nd image, and the outer frame of a 3rd image. It is a figure which shows the cell of the 2nd image expanded for a 4th image generation, and the outer frame of a 4th image. It is a flowchart which shows the perspective correction procedure in swing aori operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up device 10 A tilt shooting camera 11 Shooting lens 20 Front part 21 Mount surface 30 Rear part 31 Imaging element 41 Focus information reading part 42 Lens information reading part 44 A tilt angle reading part 50 Control part 60 Display part H1, H2 1. Second principal point LX Optical axis

Claims (6)

A lens,
An image pickup device having an image pickup surface for picking up an optical image in which a subject image is projected through the lens;
A control unit that corrects the perspective exaggerated by the swing or tilt tilt for the first image obtained by imaging with the imaging device based on the imaging magnification for each position on the imaging surface. apparatus.   The photographing magnification includes the focal length of the lens, the image distance between the surface that includes the second principal point of the lens at the time of focusing and is perpendicular to the optical axis, and the center of the imaging surface, and the tilt or tilt tilt. The imaging apparatus according to claim 1, wherein the imaging apparatus is obtained based on an angle. A lens information reading unit for acquiring information on the focal length;
A focus information reading unit that detects the image distance based on position information of a focusing lens included in the lens;
The imaging apparatus according to claim 2, further comprising a tilt angle reading unit that detects the tilt angle.   For each position on the imaging surface, the control unit enlarges or reduces the image area corresponding to the position of the imaging surface by the imaging magnification corresponding to the position of the imaging surface, thereby the rectangular shape. First image deformation means for deforming the first image into a second image having a substantially trapezoidal shape, and a rectangular region having the same aspect ratio as the aspect ratio of the first image inside the second image and taking out the first region 2. The image forming apparatus according to claim 1, further comprising: a second image deforming unit that obtains three images; and a third image deforming unit that obtains a fourth image by enlarging the third image to the same size as the first image. The imaging device described.   The imaging apparatus according to claim 4, further comprising a display unit that displays a portion of the second image that is inside the first image and the third image as a through image. The imaging apparatus according to claim 4, wherein the enlargement by the photographing magnification is performed by pixel interpolation, and the reduction by the photographing magnification is performed by pixel thinning.

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