JP4546781B2 - Imaging apparatus and color misregistration correction program - Google Patents

Description

  The present invention relates to an image pickup apparatus that picks up an image with a wide range of distances in the depth direction in focus and a color misregistration correction program.

  Conventionally, when an image is picked up by an image pickup device that picks up a subject, in order to focus on both the subject close to the lens of the image pickup device and the subject far away, the aperture of the image pickup device is narrowed down. The subject is imaged in a focused state from a close position to a distant position, that is, in a pan focus state.

The range of the distance in the depth direction that is in focus by the imaging apparatus is called the depth of field, and the depth of field L is expressed by the following equation (1). Here, S is the distance from the lens to the subject, f is the focal length of the lens, F _NO is the reciprocal of the ratio of the lens aperture to the focal length, and δ is the allowable circle of confusion that allows the optical image to spread. Represents the diameter of.

Conventionally, in a camera using a film, the lens and the film camera main body are connected by a bellows, light is blocked by the bellows, and the lens is inclined to change the angle between the optical axis of the lens and the light receiving surface of the film. There was something to be done. In such an optical system, when a distant view and a foreground are simultaneously captured, an optical image of the distant view and the foreground is formed on the film by tilting the optical axis of the lens with respect to the camera body (Patent Document). 1).
JP-A-11-119334 (paragraph numbers 0002 to 0027, FIG. 1)

  However, the resolution of the lens is affected by the aperture, and when the aperture value is increased (the aperture is reduced), the resolution characteristics are degraded due to the effect of diffraction. Therefore, if the aperture value is increased, the depth of field is increased, and the focus is adjusted from the front to the far, the resolution of the optical system is lowered. In particular, in an ultra-high-definition camera or a small camera in which the pixel size is reduced and the number of pixels is increased, it is difficult to achieve both because the depth of field and the maintenance of the optical system resolution are contradictory conditions.

  In video cameras, since the lens is fixed to the video camera body, it is difficult to apply a mechanism that connects the lens and the camera body with a bellows and tilts the optical axis of the lens with respect to the light receiving surface of the film. Met.

  The present invention has been made to solve the above-described problems of the prior art, and in a video camera in which a lens is fixed to the main body, a distant subject and a foreground subject are focused on the same screen. An object of the present invention is to provide an image pickup apparatus and a color misregistration correction program that can be used.

Furthermore, the imaging apparatus according to claim 1 is an imaging apparatus that images a subject and generates a video signal, and includes a lens, a color separation unit, an imaging unit, and an inclination unit.

  According to this configuration, the imaging apparatus forms an image of the subject with the lens, and the light emitted from the lens is divided into red light, green light, and blue light by the color separation unit. And an imaging device converts each image of red light, green light, and blue light into a video signal by an imaging means. Here, in the imaging apparatus, since the incident surface of the color separation unit is inclined with respect to the surface perpendicular to the optical axis of the lens by the inclination unit, there is a difference in the optical path length depending on the position in the same light receiving surface. Arise. For this reason, on the light receiving surface of the image pickup means, the light passing through the light path having a short optical path length forms an image of a distant subject, and the light passing through the light path having a long optical path length forms an image of a near view subject.

  The color separation means is for separating incident light into red light, green light, and blue light, and is, for example, a color separation prism. The color separation means may be a three-plate type that splits incident light into red light, green light, and blue light, or a four-plate type that further separates green light into two. Good.

The image pickup apparatus according to claim 2 is the image pickup apparatus according to claim 1 , wherein the color separation means is a color separation prism, and an incident surface of the color separation prism is perpendicular to the optical axis of the lens. A color shift amount calculating means for calculating a shift amount of each subject image of the red light, the green light, and the blue light based on the inclination with respect to the correct plane, and the shift calculated by the color shift amount calculating means. Based on the amount, the image signal of each subject image of the red light, the green light, and the blue light is corrected, and a shift correcting unit that removes the shift is provided.

  According to such a configuration, the imaging apparatus uses the color misregistration amount calculation unit to determine each of the red light, the green light, and the blue light based on the inclination of the incident surface of the color separation prism with respect to the surface perpendicular to the optical axis of the lens. The amount of displacement of the subject image is calculated. Here, the light emitted from the lens is incident on the color separation prism, and the light is refracted on the incident surface by tilting the incident surface of the color separation prism by the tilting means. The light emitted from the color separation prism forms an image on the light receiving surface of the image pickup means, but the light path is refracted when the color separation prism is tilted. Deviation occurs. In addition, since the refractive index depends on the frequency of light, red light, green light, and blue light have different refractive indexes, and there is a difference in the amount of displacement of the image forming position depending on the color of the light. For this reason, the amount of deviation depends on the inclination of the color separation prism and the frequency of the light, and the color deviation amount calculation means determines the image formed by the light of each color based on the inclination of the color separation prism. The amount of deviation can be calculated.

Further, the shift correction unit corrects the video signals of the respective subject images of red light, green light, and blue light based on the shift amount calculated by the color shift amount calculation unit, and removes the shift. Accordingly, it is possible to correct a shift in the image of the subject of red light, green light, and blue light caused by tilting the incident surface of the color separation prism in the imaging apparatus.
Furthermore, the imaging device according to claim 3, wherein the imaging unit includes a red light imaging element that captures an image of the red light imaged by the lens and generates a video signal of red light, and the lens. A blue light imaging device that generates a blue light image signal by capturing the image of the formed blue light and a green light image signal generated by capturing a green light image formed by the lens An image element for green light, and based on the inclination angle of the incident surface of the color separation prism, the optical path length of each pixel of the red light image sensor, the blue light image sensor, and the green light image sensor It further comprises strain correction means for calculating the difference and correcting the strain based on the distance.

Moreover, the color shift correction program according to claim 4, inputs a video signal from the imaging device according to claim 1, further comprising a color separation prism as a color separation means, red light and green by the color separation prism of the imaging device In order to correct a shift that occurs in an image of a subject that has been decomposed into light and blue light, the computer is caused to function as a color shift amount calculation unit and a shift correction unit.

  According to this configuration, the color misregistration correction program causes the color misregistration amount calculation means to determine the inclination of the incident surface of the color separation prism with respect to the plane perpendicular to the optical axis of the lens of the imaging device, and the red, green, and blue light. Based on the respective refractive indexes, the amount of shift of the image of each subject of the red light, the green light, and the blue light is calculated. Further, the shift correction unit corrects the video signals of the respective subject images of red light, green light, and blue light based on the shift amount calculated by the color shift amount calculation unit, and removes the shift. Accordingly, it is possible to correct a shift in the image of the subject of red light, green light, and blue light caused by tilting the incident surface of the color separation prism in the imaging apparatus.

  The imaging apparatus and color misregistration correction program according to the present invention have the following excellent effects.

  According to the first aspect of the present invention, it is possible to form images of both a distant subject and a foreground subject on the light receiving surface of the imaging means without reducing the aperture. Therefore, it is possible to capture an image in which the distant view and the close view are in focus without reducing the resolution.

  According to the second aspect of the present invention, it is possible to focus on the distant view and the close view without reducing the resolution, and the light receiving surface of the imaging unit is inclined with respect to the surface perpendicular to the optical axis. Therefore, it is possible to generate an image from which the distortion caused by the phenomenon is removed.

  According to the third aspect of the present invention, the light from the subject is decomposed into red light, green light, and blue light. Both images of the subject can be formed. For this reason, it is possible to generate video signals of the three primary colors in which the distant view and the close view are focused without reducing the resolution.

  According to the fourth aspect of the invention, it is possible to generate a video signal of the three primary colors in which the distant view and the close view are in focus without reducing the resolution, and the color separation prism is inclined from the image. The color shift caused by this can be removed.

  According to the fifth aspect of the present invention, it is possible to remove color misregistration caused by inclining the color separation prism from the video imaged by the imaging device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Configuration of Imaging Device (First Embodiment)]
First, with reference to FIG. 1, the structure of the imaging device 1 which is 1st embodiment in this invention is demonstrated. FIG. 1 is a schematic diagram schematically showing the configuration of the imaging apparatus according to the first embodiment of the present invention.

  The imaging device 1 captures an image of a subject and generates a video signal. Here, the imaging device 1 includes a lens 2, a solid-state imaging device 3, an imaging device fixing unit 4, and distortion correction means 5.

  The lens 2 receives light from a subject and forms an image of the subject. Here, the lens 2 is a convex lens, and is fixed at a predetermined distance from a solid-state imaging device 3 described later. The lens 2 may be a single lens or a lens group such as a combination of a convex lens and a concave lens.

  The solid-state imaging device (imaging means) 3 captures an image formed by the lens 2 and generates a video signal. The solid-state imaging element 3 can be configured by an optical element such as a CCD (Charged Coupled Device), for example. The video signal generated here is output to the distortion correction means 5. The imaging device 1 includes a light shielding unit (not shown). Light from the surroundings is shielded by the light shielding unit, and only the light transmitted through the lens 2 is incident on the solid-state imaging device 3. The solid-state image sensor 3 is supported by an image sensor fixing unit 4 to be described later.

  The imaging element fixing unit (tilting means) 4 holds the solid-state imaging element 3 by inclining the light receiving surface 3 a of the solid-state imaging element 3 with respect to a plane perpendicular to the optical axis of the lens 2. Here, the image sensor fixing unit 4 includes an image sensor holding unit 4a, a rotation support unit 4b, and an inclination angle measuring unit 4c.

  The image sensor holding unit 4 a holds the solid-state image sensor 3. Here, the image sensor holding unit 4a exposes and holds only the light receiving surface 3a of the solid-state image sensor 3. Moreover, the rotation support part 4b hold | maintains the image pick-up element holding | maintenance part 4a so that rotation is possible. Here, the rotation support part 4b holds the image sensor holding part 4a so as to be rotatable about a rotation axis that passes through the light receiving surface 3a of the solid-state image sensor 3 and is orthogonal to the optical axis of the lens 2. As a result, the image sensor fixing unit 4 can hold the solid-state image sensor 3 by inclining the light receiving surface 3 a of the solid-state image sensor 3 with respect to the plane perpendicular to the optical axis of the lens 2. In FIG. 1, the image pickup apparatus 1 uses the image pickup device fixing unit 4 to move the light receiving surface 3 a of the solid-state image pickup device 3 to the surface perpendicular to the optical axis of the lens 2 with an angle θ (tilt) An example in which the angle is inclined by (angle) is shown.

  The tilt angle measurement unit 4 c measures the tilt angle of the solid-state image sensor 3. Information on the tilt angle measured here is output to the strain correction means 5. Here, the inclination angle measurement unit 4c is provided inside the rotation support unit 4b.

  Here, the operation of the imaging apparatus 1 will be described with reference to FIGS. First, with reference to FIG. 2 and FIG. 3, a method of shifting the position in the depth direction in focus by inclining the light receiving surface 3 a of the solid-state imaging device 3 of the imaging device 1 with respect to a plane perpendicular to the optical axis will be described. To do. FIG. 2 is an explanatory diagram schematically showing an optical path of light that passes through the lens and forms an image on the light receiving surface of the solid-state imaging device in the imaging apparatus of FIG. 1. FIG. 3 is an explanatory diagram schematically showing the focal depth of the lens and the diameter of the allowable circle of confusion.

  As shown in FIG. 2, the difference between the distance from the upper side of the light receiving surface 3 a of the solid-state imaging device 3 to the lens 2 and the distance from the intersection of the optical axis of the lens 2 and the light receiving surface 3 a of the solid-state imaging device 3 to the lens 2. Is (a / 2) sin θ, where a is the length of the vertical side of the light receiving surface 3a of the solid-state imaging device 3. Similarly, the difference between the distance from the intersection of the optical axis and the light receiving surface 3a to the lens 2 and the distance from the lower side of the light receiving surface 3a to the lens 2 is (a / 2) sin θ.

As shown in FIG. 3, when light passing through the lens 2 forms an image on the light receiving surface 3a of the solid-state imaging device 3, there is a range where there is no image blur before and after the light receiving surface 3a. The distance in the optical axis direction within this range is called the depth of focus. The depth of focus is determined only by the diameter δ and F value F _NO of the permissible circle of confusion it can be expressed as .delta.F _NO.

Therefore, when the light receiving surface 3a of the solid-state imaging device 3 is tilted as shown in FIG. 2, the positions of the objects O _b and O _c formed on the upper side or the lower side of the light receiving surface 3a are shifted in the depth direction so that the solid-state imaging is performed. In order to shift the focus position in the image picked up by the element 3, the focal depth range of the upper side or the lower side when the light receiving surface 3a is tilted and the light receiving surface 3 directly facing the lens 2 (perpendicular to the optical axis). ), The tilt angle θ may be determined so that the following equation (2) is satisfied.

(A / 2) sin θ ≧ 2δF _NO Expression (2)

Further, when the distance from the subject O _a on the optical axis to the subject side focal point F _O is x _O and the distance from the image side focal point F _I to the image of the subject O _a is x _I , the following equation (3) ( Newton's formula) holds. Note that f is the focal length of the lens 2.

x _O · x _I = f ² Formula (3)

The distances from the subjects O _b and O _{c that} are in focus to the upper and lower sides of the light receiving surface 3a of the solid-state imaging device 3 to the subject-side focal point F _O are (x _O −Δx ₁ ) and (x _O + Δx ₂ ), respectively. When each distance from the image-side focal point F _I to the upper side and the lower side of the light receiving surface _{3a [x I + (a /} 2) sinθ] and - for a _{[x I (a / 2)} sinθ], Newton From the formula, the following formulas (4) and (5) hold.

(X _O −Δx ₁ ) [x _I + (a / 2) sin θ] = f ² Formula (4)
(X _O + Δx ₂ ) [x _I − (a / 2) sin θ] = f ² Formula (5)

Then, when formulas (4) and (5) are summarized for Δx ₁ and Δx ₂ based on formula (3), the following formulas (6) and (7) are derived.

Here, eg, F value F _NO of the lens 2 is 2, the focal length f is 18 mm, a pixel size of the solid-state imaging device 3 is 5 [mu] m, the optical size of 2/3 inch (16.9 mm), the aspect ratio is 16: If it is 9, the minimum inclination angle θ for inclining the light receiving surface 3a can be obtained from Expression (2) as shown in Expression (8) below. Here, the diameter δ of the permissible circle of confusion is 5 μm, which is the pixel size. The length a of the vertical side of the light receiving surface 3a was set to 8.3 mm based on the optical size and the aspect ratio.

θ = sin ⁻¹ (4δF _NO /a)=0.2048 [°] (8)

  Therefore, if the inclination angle θ of the light receiving surface 3a of the solid-state imaging device 3 is set to 0.0048 ° or more, the in-focus position can be shifted in the depth direction. The solid-state image sensor 3 can be tilted at an arbitrary angle by a stepping motor (not shown) and a gear (not shown), and the solid-state image sensor 3 can be supported in its posture. In addition, the imaging apparatus 1 of the present invention may manually adjust the tilt angle. And when tilting a minute angle, it is good also as adjusting a tilt angle via the gear which converts manual rotation into rotation of a minute angle, for example.

  For example, when imaging a subject (not shown) whose distance from the lens 2 is in the range of 5 m to 10 m, the light receiving surface 3a is made perpendicular to the optical axis of the lens 2 as in a conventional imaging device. Assuming that the lens 2 is focused 5 m away from the lens 2, the depth of field in the rear direction (rear depth of field) can be calculated as about 0.9 m by the above equation (1). Therefore, when focusing 5m ahead, it will not focus 10m away. If the lens 2 is focused 10 m ahead, the depth of field in the forward direction (forward depth of field) is calculated to be about 2.4 m according to the above equation (1). Therefore, if you focus 10m ahead, you will not be able to focus 5m away.

  Therefore, when the lens 2 is focused 7.5 m ahead and the light receiving surface 3a of the solid-state imaging device 3 is tilted, it can be focused 5 m or 10 m ahead. The inclination angle θ at this time is obtained as 0.0052 ° from the above equation (6). When the subject is focused 7.5 m ahead, there is a subject ahead of the point 7.5 m downward from the optical axis direction and 7.5 m upward from the optical axis direction. When there is a subject behind the point, as shown in FIG. 2, the image of the subject ahead of the subject 7.5 m ahead is obtained by inclining the upper side of the solid-state imaging device 3 away from the lens 2. An image of a subject behind the subject that is 7.5 m ahead can be formed in the lower half region in the upper half region of the image sensor 3.

  In addition, when there is a front subject in the upward direction when viewed from the optical axis direction and there is a rear subject in the downward direction, the lower side of the solid-state imaging device 3 is inclined so as to be away from the lens 2, An image of the subject can be formed on the light receiving surface 3 a of the solid-state image sensor 3. In this way, the imaging apparatus 1 can focus and image the entire subject in a wide range without reducing the aperture.

  Here, the case where the light receiving surface 3a of the solid-state imaging device 3 is tilted with respect to a plane perpendicular to the optical axis of the lens 2 about a horizontal rotation axis orthogonal to the optical axis of the lens 2 has been described. However, the image sensor fixing unit 4 only needs to be capable of supporting the solid-state image sensor 3 by tilting it.

  For example, the image sensor fixing unit 4 may be tilted around a vertical rotation axis orthogonal to the optical axis of the lens 2. Then, when there is a subject ahead in the right or left direction and a subject behind in the left or right direction as viewed from the optical axis direction, the left side or the right side of the solid-state imaging device 3 is inclined so as to be away from the lens 2, respectively. Thus, an image of the subject can be formed on the light receiving surface 3a of the solid-state imaging device 3. Further, the image sensor fixing unit 4 may tilt the solid-state image sensor 3 around a rotational axis in an oblique direction orthogonal to the optical axis of the lens 2. When tilted about the vertical rotation axis, a is the length of the side of the light receiving surface 3a, and when tilted about the oblique rotation axis, a is the light receiving surface 3a. The length of the diagonal line.

  Here, an example in which the light receiving surface 3a of the solid-state image sensor 3 is tilted so that a distant subject and a foreground subject are in focus has been described. For example, the light receiving surface 3a of the solid-state image sensor 3 is tilted. The focus position may be shifted so that when the light receiving surface 3a is perpendicular to the optical axis of the lens 2, the subject within the depth of field is not focused. Thereby, the imaging device 1 can capture an image in which a part of the image is intentionally blurred.

In addition, by setting the tilt angle θ so that the value of the denominator on the right side of the equation (7) approaches zero, the imaging apparatus 1 can be brought into focus at infinity, that is, in pan focus. Can be imaged. Here, with reference to FIG. 4, a method of imaging a subject with panning focus using the imaging apparatus 1 will be described. FIG. 4 is a graph showing the relationship between the tilt angle θ for pan focus and the distance x _O from the subject on the optical axis to the subject-side focal point.

For example, when the lens 2 having a focal length f of 18 mm and the solid-state image pickup device 3 having an optical size of 2/3 inch are used, the pan focus is achieved, that is, the inclination in which the denominator of the right side of the equation (7) is zero. The relationship between the angle θ and the distance x _O from the subject on the optical axis to the subject-side focus F _O is as shown in FIG. For example, when the distance x _O on the optical axis is 1 m away, pan-focusing can be performed by inclining the solid-state imaging device 3 by 0.1 °.

  Returning to FIG. 1, the description will be continued. The distortion correction means 5 corrects the video signal input from the solid-state image sensor 3 and generates a video signal from which distortion due to the tilt of the solid-state image sensor 3 is removed. Here, the distortion correction means 5 calculates the distance from the focal point of the lens 2 to each pixel of the light receiving surface 3a based on the inclination angle of the light receiving surface 3a of the solid-state imaging device 3, and corrects the distortion based on the distance. can do. Here, it is assumed that the strain correction means 5 receives information on the tilt angle of the solid-state imaging device 3 from the tilt angle measurement unit 4c.

  Here, with reference to FIG. 5, a method of performing the correction for removing the distortion by the distortion correcting means 5 will be described. FIG. 5A is a schematic diagram illustrating an imaging model of a foreground object and a distant object when the solid-state image sensor is tilted, and FIG. 5B is an image captured by the solid-state image sensor of FIG. It is explanatory drawing which showed the example which removes the distortion | strain.

As shown in FIG. 5 (a), the light-receiving surface 3a of the object in the foreground (foreground subject) O _n and distant subject solid-state image pickup device 3 for imaging the (distant view object) O _f (see FIG. 1), the optical axis It is inclined by an inclination angle θ with respect to a vertical plane. Then, the tip of the arrow of the distant object O _f is, on the light receiving surface 3a, and imaged from the image side focal point F _I in a position at a distance dx _f in the optical axis direction, the tip of the arrow in the foreground object O _n, light on the plane 3a, and is imaged at a position apart dx _n from the image side focal point F _I in the optical axis direction. Then, the magnification of the image of these objects O _f, O _n is a respective dx _f / f and dx _n / f. Since the magnification when the light receiving surface 3a is not tilted is dx _m / f, the magnification of these subject images with respect to the case where the light receiving surface 3a is not tilted is dx _f / dx _m and dx _n / dx _m , respectively. . Incidentally, dx _m is the distance in the direction of the optical axis to the image side focal point F _I in the case of not tilting the light receiving surface 3a, the rotation axis by tilting the light receiving surface 3a center, i.e. to the image side focal point F _I This is the distance to the portion where the distance in the optical axis direction does not change.

Since a _{dx f <dx m <dx n} , the light receiving surface 3a, the magnification of the image of the distant object O _f is smaller than the magnification of the image in the foreground object O _n, imaged in a position close to the lens 2 so far image of the object O _f is smaller than the image in the case of not tilting the light receiving surface 3a. Then, the image picked up by the solid-state image pickup device 3 has a trapezoidal distortion in which the image of the distant view is reduced and the rectangle is deformed into a trapezoid as shown by a broken line in FIG. Note that the distortion correcting means 5 removes the trapezoidal distortion based on the reciprocal of the magnification compared to the case where the light receiving surface 3a is not inclined due to the inclination of the light receiving surface 3a.

Therefore, distortion correcting means 5, for each pixel on the light receiving surface 3a, for foreground object O _n, is corrected to the distance of dx _m / dx _n multiplied by the position of the intersection point m between the light-receiving surface 3a and the optical axis for the distant object O _f, it is corrected to a position where the distance was doubled dx _m / dx _f from the intersection m, video trapezoidal indicated by a broken line in FIG. 5 (b) to expand and shrink the entire screen Is deformed, and the trapezoidal distortion can be removed.

  By configuring the imaging device 1 as described above, the imaging device 1 changes the distance in the depth direction in focus on the same light receiving surface 3a according to the inclination angle of the light receiving surface 3a of the solid-state imaging device 3. An image can be taken. In addition, the imaging apparatus 1 can correct a video signal captured by the solid-state imaging device 3 and remove distortion caused by tilting the light receiving surface 3 a of the solid-state imaging device 3.

(Operation of imaging device)
Next, the operation of the imaging apparatus 1 according to the first embodiment of the present invention will be described with reference to FIG. Here, a case where there is a subject in the foreground in the downward direction and a subject in the foreground in the upward direction as viewed from the optical axis direction of the lens 2 will be described.

  The imaging apparatus 1 focuses on a subject on the optical axis of the lens 2. Then, an inclination angle corresponding to the distance in the depth direction of the subject imaged by the imaging device 1 with respect to the surface orthogonal to the optical axis around the rotation axis of the rotation support portion 4b. Just tilt. Here, the solid-state imaging device 3 is tilted by a stepping motor (not shown) via a gear (not shown). The image sensor fixing unit 4 tilts the light receiving surface 3a obliquely upward so that a distant subject is imaged below the light receiving surface 3a of the solid-state image sensor 3, and a near subject is imaged above the light receiving surface 3a. Let me support you. Then, the tilt angle measurement unit 4 c of the image sensor fixing unit 4 measures the tilt angle of the solid-state image sensor 3 and outputs information on the tilt angle to the distortion correction means 5.

  As a result, the distance from the lens 2 to the light receiving surface 3 a gradually increases from the lower side to the upper side of the light receiving surface 3 a, so that the subject on the optical axis of the lens 2 is the light receiving surface 3 a on the light receiving surface 3 a of the solid-state imaging device 3. An image is formed in the vicinity of the intersection of the light axis and the optical axis, and a distant subject is imaged in the lower part of the light receiving surface 3a and a near object is imaged in the upper part.

The image of the subject formed on the light receiving surface 3a is picked up by the solid-state image pickup device 3 and converted into a video signal. Here, the distortion of the image of the subject due to the inclination of the light receiving surface 3a occurs. That is, since the light receiving surface 3 a is inclined obliquely upward, the lower part is relatively closer to the lens 2 and the upper part is farther from the lens 2. Therefore, the image formed on the lower part of the light receiving surface 3a is reduced more than the image formed on the upper part. The magnification of the image formed in each pixel with respect to the actual object is proportional to the distance from the image-side focal point F _I (see FIG. 5) of the lens 2 to the pixel.

  Therefore, the distortion correction unit 5 calculates the distance from each pixel of the solid-state image sensor 3 to the focal point of the lens 2 based on the information on the tilt angle of the light receiving surface 3a of the solid-state image sensor 3 received from the tilt angle measurement unit 4c. To do. Based on this distance, the distortion correction means 5 corrects the video signal received from the solid-state imaging device 3 so that the magnification of the subject of the video indicated by the video signal with respect to the real object is constant for all pixels. To do.

[Configuration of Imaging Device (Second Embodiment)]
Next, with reference to FIG. 6, a configuration of an imaging apparatus 1A according to the second embodiment of the present invention will be described. FIG. 6 is a schematic diagram schematically showing the configuration of the image pickup apparatus according to the second embodiment of the present invention. As shown in FIG. 6, the imaging apparatus 1A captures an image of a subject to generate a three primary color video signal, corrects this video signal, and corrects the video shift and trapezoidal distortion indicated by the three primary color video signals. The removed video signal is generated.

  The imaging apparatus 1A includes a lens 2, a distortion correction unit 5A, a color separation prism 6A, a red light imaging device 7A, a blue light imaging device 8A, a green light imaging device 9A, and a color misregistration correction unit 10A. And a color separation prism fixing unit (tilting means) (not shown). The color separation prism fixing unit includes a color separation prism holding portion (not shown) that holds a color separation prism 6A described later, and a rotation support portion (not shown) that rotatably supports the color separation prism holding portion. The color separation prism 6A, which will be described later, is supported so as to be rotatable about a rotation axis orthogonal to the optical axis of the lens 2 through the incident surface of the color separation prism 6A. Here, the imaging apparatus 1A tilts the color separation prism 6A at an arbitrary tilt angle by a stepping motor (not shown) and a gear (not shown). The imaging apparatus 1A includes an inclination angle measurement unit (not shown) that measures the inclination angle of the color separation prism 6A, and information on the inclination angle is output to the color misregistration correction unit 10A and the distortion correction unit 5A. And Further, the lens 2 in the image pickup apparatus 1A is the same as that shown in FIG.

  The color separation prism (color separation means) 6A is disposed on the optical axis of the lens 2 and separates light incident from the lens 2 into light of three primary colors of red light, green light, and blue light. The color separation prism 6A includes a red light separation prism 6Aa, a blue light separation prism 6Ab, and a green light transmission prism 6Ac. The color separation prism 6A is rotatably supported by a color separation prism fixing unit (not shown).

  The red light separation prism 6Aa separates red light from the light incident from the lens 2 and guides the red light to a red light imaging device 7A described later. The red light separation prism 6Aa includes a dichroic mirror Ma that reflects red light from the light incident from the lens 2 on a surface in contact with the blue light separation prism 6Ab. Then, the red light separating prism 6Aa reflects the red light reflected by the dichroic mirror Ma again within the red light separating prism 6Aa, and then is bonded to the end face or fixed at a predetermined interval. To the image sensor 7A. The light transmitted through the dichroic mirror Ma enters the blue light separation prism 6Ab.

  The blue light separation prism 6Ab separates blue light from the light incident from the red light separation prism 6Aa and guides the blue light to a blue light imaging element 8A described later. The blue light separation prism 6Ab includes a dichroic mirror Mb that reflects blue light from the light incident from the red light separation prism 6Aa on a surface in contact with the green light separation prism 6Ac. Then, the blue light separating prism 6Ab reflects the blue light reflected by the dichroic mirror Mb again in the blue light separating prism 6Ab, and is then bonded to the end face or fixed at a predetermined interval. To the image sensor 8A. Here, the green light transmitted through the dichroic mirror Mb is incident on the green light transmitting prism 6Ac.

  The green light transmitting prism 6Ac guides the light incident from the blue light separating prism 6Ab to the green light imaging element 9A described later. On the end face of the green light transmitting prism 6Ac, a green light image pickup element 9A is bonded or fixed at a predetermined interval.

  The red light imaging device (imaging means) 7A captures a red light image formed by the lens 2 and generates a red light video signal. The red light video signal generated here is output to the color misregistration correction means 10A.

  The blue light imaging element (imaging means) 8A captures a blue light image formed by the lens 2 and generates a blue light video signal. The blue light video signal generated here is output to the color misregistration correction means 10A.

  The green light imaging element (imaging means) 9A captures a green light image formed by the lens 2 and generates a green light video signal. The green light video signal generated here is output to the color misregistration correction means 10A.

  The red light imaging element 7A, the blue light imaging element 8A, and the green light imaging element 9A are fixed to the color separation prism 6A, and the color separation prism 6A is rotated by a color separation prism fixing unit (not shown). It is supported freely. Therefore, when the incident surface of the color separation prism 6A is inclined by a certain inclination angle θ, the light receiving surfaces of the red light imaging element 7A, the blue light imaging element 8A, and the green light imaging element 9A are not inclined. It is inclined by an inclination angle θ with respect to each light receiving surface.

  The color misregistration correction unit 10A corrects the three primary color video signals input from the red light imaging element 7A, the blue light imaging element 8A, and the green light imaging element 9A, and the inclination of the incident surface of the color separation prism 6A. This is to remove the deviation of the image of the subject indicated by each video signal, which is caused by the difference in refractive index between red light, green light and blue light. The color misregistration correction unit 10A includes a color misregistration amount calculation unit 10Aa and a misregistration correction unit 10Ab.

  The color misregistration amount calculation unit (color misregistration amount calculation means) 10Aa is based on the inclination of the incident surface of the color separation prism 6A with respect to the optical axis of the lens and the refractive index of the light of each color. The amount of deviation generated in the image is calculated. Information on the amount of deviation calculated here is output to the deviation correction unit 10Ab.

  Here, with reference to FIG. 7, a method by which the color misregistration amount calculation unit 10Aa calculates the misregistration amount will be described. FIG. 7A is an explanatory diagram schematically illustrating the relationship between the incident angle and the refraction angle of light, and FIG. 7B is an explanatory diagram schematically illustrating the optical path of light incident on the prism.

  As shown in FIG. 7A, when light enters a medium having a refractive index n ′ from a medium having a refractive index n, the relationship between the light incident angle θ and the refractive angle θ ′ is expressed by the following equation: (9) (Snell's law)

  n · sin θ = n ′ · sin θ ′ (9)

  Therefore, when the incident surface of the color separation prism 6A is inclined with respect to the surface perpendicular to the lens 2 by an inclination angle θ, for example, light on the optical axis enters the color separation prism 6A at the incident angle θ. . At this time, since the refractive index n of air is 1, the refraction angle θ ′ is θ′≈sin θ ′ = sin θ / n ′, and the emission angle emitted from the color separation prism 6A is θ.

  Here, a case where light is not reflected in the prism P as illustrated in FIG. 7B will be described as an example. When the width of the prism P is b and the distance from the prism P to the image sensor D is c, the deviation of the incident position with respect to the image sensor D when the prism P is not tilted is a · tan θ ′ + b · tan θ. Calculated by The refractive index n ′ is represented by the following formula (10). A and B are constants, and λ is the wavelength of light.

n ′ = A + B / λ ² Formula (10)

  As shown in Expression (10), since the refractive index n ′ depends on the wavelength λ of light, the amount of deviation of the incident position when the prism P is inclined with red light, green light, and blue light. Is different. Therefore, the color misregistration amount calculation unit 10Aa can calculate the misregistration amount from the equation (10) for each color light based on the tilt angle information input from the tilt angle measurement unit (not shown). it can.

  Returning to FIG. 6, the description will be continued. The deviation correction unit (deviation correction means) 10Ab converts the video signals of red light, green light, and blue light input from the red light imaging element 7A, the blue light imaging element 8A, and the green light imaging element 9A into color signals. Correction is performed based on the amount of deviation input from the deviation amount calculation unit 10Aa. The three primary color video signals corrected here are output to the distortion correction means 5A.

  The distortion correction unit 5A corrects the video signal input from the shift correction unit 10Ab to generate a video signal from which distortion due to the inclination of the incident surface of the color separation prism 6A is removed. Here, the distortion correction unit 5A determines the optical path length of each pixel of the red light imaging element 7A, the blue light imaging element 8A, and the green light imaging element 9A based on the inclination angle of the incident surface of the color separation prism 6A. The difference can be calculated and the distortion can be corrected based on the distance. Note that the distortion correction means 5A has the same function, except that the input signal compared to the distortion correction means 5 is a video signal of the three primary colors from the video signal, and the distortion is removed from the video signal of each color. Is. The three primary color video signals corrected here are output to the outside.

  By configuring the image capturing apparatus 1A as described above, the image capturing apparatus 1A is configured to capture the red light image sensor 7A, the blue light image sensor 8A, and the green light image according to the inclination angle of the incident surface of the color separation prism 6A. On the light receiving surface of the element 9 </ b> A, it is possible to capture an image in which the distance in the in-focus depth direction is changed. Further, the color misregistration correction unit 10A corrects each video signal imaged by the red light imaging element 7A, the blue light imaging element 8A, and the green light imaging element 9A, and inclines the incident surface of the color separation prism 6A. Can be eliminated.

  Note that the color misregistration correction unit 10A can be realized as each function program in a computer, and can be operated as a color misregistration correction program by combining the function programs.

  Furthermore, the imaging device 1 of the present invention only needs to include at least the lens 2, the solid-state imaging device 3, and the imaging device fixing unit 4. The image output from the imaging device 1 includes distortion due to the tilting of the solid-state imaging device 3, but the distortion is small if the tilt angle is small. The imaging apparatus 1 includes the distortion correction unit 5, whereby the distortion is removed by the distortion correction unit 5, and the imaging apparatus 1 that outputs a video signal of higher quality can be obtained.

  Similarly, the imaging apparatus 1A of the present invention includes at least a lens 2, a color separation prism 6A, a red light imaging element 7A, a blue light imaging element 8A, a green light imaging element 9A, and a color separation prism fixed. What is necessary is just to provide a unit (not shown). The image output from the image pickup apparatus 1A includes color shift and distortion caused by tilting the color separation prism 6A, the red light image pickup element 7A, the blue light image pickup element 8A, and the green light image pickup element 9A. However, if the tilt angle is small, the color shift and distortion are also small. Since the image pickup apparatus 1A includes the distortion correction unit 5 and the color misregistration correction unit 10A, the color misregistration correction unit 10A removes the color misregistration, and the distortion correction unit 5 removes the distortion. The imaging apparatus 1A can generate a video signal of the three primary colors of a good video.

It is the schematic diagram which showed typically the structure of the imaging device which is 1st embodiment in this invention. FIG. 2 is an explanatory diagram schematically illustrating an optical path of light that passes through a lens and forms an image on a light receiving surface of a solid-state imaging device in the imaging apparatus of FIG. 1. It is explanatory drawing which shows typically the focal depth of a lens, and the diameter of a permissible circle of confusion. It is the graph which showed the relationship between the inclination angle used as pan focus, and the distance from the to-be-photographed object side focus on the optical axis. (A) is a schematic diagram showing an imaging model of a foreground object and a distant object when the solid-state image sensor is tilted, and (b) is a distortion of an image captured by the solid-state image sensor of (a). It is explanatory drawing which showed the example which removes. It is the schematic diagram which showed typically the structure of the imaging device which is 2nd embodiment in this invention. (A) is explanatory drawing which showed typically the relationship between the incident angle and refraction angle of light, (b) is explanatory drawing which showed typically the optical path of the light which injects into a prism.

Explanation of symbols

1, 1A imaging device 2 lens 3 solid-state imaging device (imaging means)
3a Light-receiving surface 4 Image sensor fixing unit (tilting means)
5 Distortion correction means 6A Color separation prism (color separation means)
7A Image sensor for red light (imaging means)
8A Image sensor for blue light (imaging means)
9A Green light imaging device (imaging means)
10A color misregistration correction means 10Aa color misregistration amount calculation unit (color misregistration amount calculation means)
10 Ab Deviation correction unit (deviation correction means)

Claims (4)

An imaging device that images a subject and generates a video signal,
A lens that receives light from the subject and forms an image of the subject;
A color separation means that is installed on the optical axis of the lens and receives light emitted from the lens and separates the light into red light, green light, and blue light;
Imaging means for converting the image of the subject formed by the lens with each light emitted from the color separation means into the video signal;
An image pickup apparatus comprising: tilting means for tilting an incident surface of the color separation means with respect to a plane perpendicular to an optical axis of the lens. The color separation means is a color separation prism;
A color shift amount for calculating a shift amount of the image of each subject of the red light, the green light, and the blue light based on the inclination of the incident surface of the color separation prism with respect to the plane perpendicular to the optical axis of the lens A calculation means;
Based on the amount of deviation calculated by the color deviation amount calculating means, a correction means for correcting the video signal of the subject image of each of the red light, the green light, and the blue light and removing the deviation. The imaging apparatus according to claim 1 , further comprising: The imaging means captures the red light image sensor that captures the red light image formed by the lens and generates a red light image signal, and the blue light image formed by the lens. A blue light imaging element that generates a blue light video signal, and a green light imaging element that captures a green light image formed by the lens and generates a green light video signal,
Based on the inclination angle of the incident surface of the color separation prism, a difference in optical path length of each pixel of the red light image sensor, the blue light image sensor, and the green light image sensor is calculated, and based on the distance. The imaging apparatus according to claim 2, further comprising a distortion correction unit that corrects the distortion. Inputs a video signal from the imaging device according to claim 1, further comprising a color separation prism as a color separation means, resulting in an image of the subject is decomposed into red light, green light and blue light by the color separation prism of the imaging device To correct the misalignment, the computer
Based on the inclination of the incident surface of the color separation prism with respect to the surface perpendicular to the optical axis of the lens of the imaging device and the respective refractive indices of red light, green light, and blue light, the red light and green light Color deviation amount calculating means for calculating the amount of deviation of the image of each subject of light and blue light,
Based on the amount of deviation calculated by the color deviation amount calculation means, the video signal of the image of each subject of the red light, green light, and blue light input from the imaging device is corrected, and the deviation is corrected. A color misregistration correction program that functions as misregistration correction means for removing color.

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