JPH11341522A - Stereoscopic image photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the stereoscopic image photographing device by which a stereoscopic image with excellent quality is obtained where distortion of left/right images is less independently of a distance up to an object. SOLUTION: A range finding means is used to detect an object distance and an inter-lens distance and a convergence angle of left right cameras 12, 14 are changed depending on the object distance to photograph the object. Then image data acquired by the cameras 12, 14 are led to an image processing circuit 20, where the image data are processed to correct distortion in the image depending on the convergence angle. In addition, camera with a swing mechanism are in use and a lens optical axis is tilted toward the object by using the swing mechanism while keeping light receiving planes of each camera in parallel to reduce distortion in the image resulting from the convergence angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional image photographing apparatus applied to a photographic camera, a video camera, and the like, and more particularly to a photographing apparatus for producing a three-dimensional image using binocular parallax.

[0002]

2. Description of the Related Art A method of obtaining a stereoscopic image by photographing the same subject using two photographing optical systems (cameras) and using the images captured by each camera as an image for the left eye and an image for the right eye is known. There have been many proposals. In general,
When the lens optical axes of the left and right cameras are set in parallel, the distance to the subject (L) and the distance between the lenses of both cameras (d ₀ )
Ratio has been and is preferably about _{d 0 / L = 1 / 30~1} / 50, when the object is far away can perform good shooting.

However, in short-distance photography, there is a physical limit in reducing the distance between the left and right lenses, so that it is difficult to perform stereoscopic photography with the parallel optical axis. To enable short-distance photography with the parallel optical axis, the amount of shift of the image position on the light receiving surface becomes large, so an extremely large optical system must be used so that the image does not protrude from the image circle. .

From the viewpoint of solving the problems, for example, Japanese Patent Application Laid-Open Nos. 8-223606, 6-105339, 5-336548, and 5
As disclosed in Japanese Patent Application Laid-Open No. 197945, a method has been proposed in which the optical axes of the left and right cameras are directed toward the subject in accordance with the distance to the subject in order to correctly capture the subject with two cameras.

[0005]

However, the methods disclosed in the above publications merely change the convergence angles of the right and left cameras according to the distance to the subject.
No mention is made of distortion of the left and right images due to convergence. As shown in FIG. 8, the left and right cameras 60, 6
When a square subject 64 is photographed with 2 having a convergence angle (α), image distortion irrespective of depth occurs in the left and right images, as shown in FIG. 9, making stereoscopic vision difficult. Observing such a distorted stereoscopic image has the disadvantage that the viewer feels tired. In particular, since the angle of convergence in short-range shooting is relatively large, distortion of the left and right images becomes extremely problematic.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a three-dimensional image photographing apparatus capable of obtaining a high-quality three-dimensional image with little left and right image distortion regardless of the distance to the subject. Aim.

[0007]

According to one aspect of the present invention, there is provided a stereoscopic image photographing apparatus having two cameras, the distortion correction for reducing image distortion caused by a convergence angle. Means are provided. According to the present invention, when photographing a common subject with two cameras having a convergence angle, the distortion of an image acquired by each camera is corrected by the correction unit according to the convergence angle, so that there is no distortion. Left and right images can be obtained. Thereby, a good stereoscopic image can be created.

According to a second aspect of the present invention, in order to propose a more specific form of the first aspect of the present invention, a three-dimensional image provided with two cameras having image pickup means for converting image light into an electric signal. In a photographing device, a convergence angle variable mechanism that changes a convergence angle by changing a direction of a lens optical axis of at least one camera, and a unit that processes an image signal acquired by the camera, and an image is formed according to the convergence angle. And image signal processing means for performing correction to reduce distortion of the image signal.

A three-dimensional image photographing apparatus according to the present invention utilizes a camera for converting image light showing a subject into an electronic image, and performs image processing of image data acquired by these cameras afterward by image signal processing means. This corrects the distortion between the two images. As a result, it is possible to obtain a high-quality three-dimensional image with little distortion of the left and right images. In this case, in particular, as in claim 3, the convergence angle variable mechanism is provided with an electric driving means, a detecting means for detecting a distance to a subject, and the electric driving means according to the subject distance obtained by the detecting means. And a control means for controlling the angle of convergence, and automatically adjusting the convergence angle according to the subject distance.

According to a fourth aspect of the present invention, in order to propose another embodiment embodying the first aspect of the present invention, in a stereoscopic image photographing apparatus having two cameras, a camera having a tilt mechanism is provided. By using the tilt mechanism to tilt the lens optical axis toward the subject while maintaining the light receiving surfaces of the cameras parallel to each other, image distortion due to the convergence angle is reduced. Features.

According to a fourth aspect of the present invention, there is provided a three-dimensional image photographing apparatus including a camera having a tilt mechanism capable of changing a relationship between a lens optical axis and a light receiving surface. The angle of convergence is given by adjusting with.
At this time, since the light receiving surfaces of both cameras are kept parallel to each other, an image without distortion can be obtained. In this case, in particular, the tilt mechanism is provided with an electric driving means, and the detecting means for detecting the distance to the subject and the electric driving means are controlled in accordance with the subject distance obtained by the detecting means. And a control means for automatically adjusting the convergence angle according to the subject distance.

The camera having the tilt mechanism used in the three-dimensional image photographing apparatus may be a silver halide camera for recording a subject image on a photographic film, or an image pickup apparatus for converting image light into an electric signal. A camera using means may be used. Like the stereoscopic image photographing device according to claim 3 or 5,
When the function of automatically adjusting the convergence angle is provided, as one mode of control, when the distance to the subject is longer than a predetermined distance, the lens optical axes of the two cameras are set as described in claim 7. It is conceivable to control the electric driving means so as to provide a convergence angle by inclining the lens optical axis of each camera when photographing a subject at a distance shorter than a predetermined distance while maintaining the distance in parallel.

[0013] In the stereoscopic image photographing apparatus according to any one of claims 1 to 7, the variable lens spacing for adjusting the distance between the lenses of the two cameras as described in claim 8. It is preferable to add a mechanism. Especially,
According to the ninth aspect of the present invention, the lens spacing variable mechanism has a second
It is preferable that the electric driving means is provided and the second control means for controlling the second electric driving means is provided in accordance with the object distance obtained by the detecting means, so that the convergence angle and the distance between the lenses are automatically adjusted.

As one mode of control of the three-dimensional image photographing apparatus according to the ninth aspect, as described in the tenth aspect, when the subject distance is a range farther than a predetermined distance value, the lenses of two cameras are used. When the distance between the lenses is adjusted in accordance with the object distance while maintaining the optical axis in parallel, and when photographing an object closer than the predetermined distance value, the lens optical axis of each camera is inclined to converge the angle of convergence. It is conceivable to control so as to give

As one mode of the means for detecting the subject distance, as described in claim 11, two cameras serving as a photographing system are used, and a base line length corresponding to a distance between lenses and a camera directed toward the subject are used. It is conceivable to employ means for determining the distance to the subject based on the convergence angle defined by the direction of the lens optical axis. Thus, there is no need to provide a separate distance measuring means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a stereoscopic image photographing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a stereoscopic image photographing apparatus according to an embodiment of the present invention. This three-dimensional image photographing apparatus 10
Mainly, two cameras 12 and 14 corresponding to an imaging device
And a camera support device 16 for rotatably and slidably supporting the cameras 12 and 14, a lens adjusting device 18, an image processing circuit 20 for processing image signals, and a control device 22.

Although the detailed structure of the cameras 12 and 14 is not shown, the two cameras 12 and 14 have the same optical system,
Each is provided with a photographic lens having the same specifications and a solid-state image pickup device (CCD) as an image pickup means. In addition, the imaging means,
Not only a CCD but also other types of imaging devices or an imaging tube may be used. The photographing lens is formed by combining a plurality of lenses, and includes a diaphragm mechanism for adjusting the amount of light, a focus adjusting mechanism for moving and adjusting the image plane in the optical axis direction, and a zoom mechanism for variably adjusting the photographing magnification (focal length). ing.

Each of the aperture mechanism, the focus adjustment mechanism, and the zoom mechanism is provided with a corresponding electric driving means such as a motor, and the control device 22 controls the lens adjusting device 18 including the electric driving means. Under the control, adjustment of the aperture, focus (focus), and zoom (focal length) of the cameras 12 and 14 is performed. The image light formed on the light receiving surface of the CCD through the taking lens is
Thus, the signal charge is converted into an amount of signal charge corresponding to the amount of light.
The signal charges thus accumulated are sequentially transferred based on a driving pulse applied from a CCD driving circuit, and are read out as a voltage signal corresponding to the signal charges. And CCD
Are read out from the image processing circuit 20.

The camera support device 16 includes the rotary table 2
4 and 25 and a slide table 26. The cameras 12 and 14 are rotatably held in a horizontal plane via rotary tables 24 and 25, respectively, and are moved left and right in FIG. Freely supported. The left camera 12 in the drawing corresponds to a left-eye camera, and the right camera 14 corresponds to a right-eye camera. These left and right cameras 12 and 14 are aligned by a camera support device 16 so that their heights with respect to a horizontal plane match. They are arranged side by side. Each of the rotary tables 24 and 25 and the slide table 26 has an electric driving unit (not shown), and the control device 22 controls the directions of the cameras 12 and 14 (the directions of the lens optical axes) and
The distance between the two cameras (the distance between the lenses) is controlled.

The image processing circuit 20 includes, in addition to analog processing circuits such as a CDS clamp circuit and a gain adjustment circuit, digital processing circuits such as an A / D converter, a luminance signal generation circuit, a color difference signal generation circuit, and a compression / decompression circuit. Including. Image processing circuit 20
Generates image data representing a subject image by appropriately processing the image signals received from the cameras 12 and 14. In particular, the image processing circuit 20 has an image correction processing function of correcting distortion of images obtained by the two cameras 12 and 14. The method of this distortion correction will be described later.

The data processed by the image processing circuit 20 is
After decoding, it is supplied to the monitor 28. Thus, the images captured by the cameras 12 and 14 are displayed on the screen of the monitor 28. Before receiving a shooting start signal generated by pressing a release switch (not shown) or the like, a preview image (confirmation moving image or intermittent image monitored before actual shooting) is displayed on monitor 28, and shooting is started. When the signal is received, the screen of the monitor 28 freezes (freezes)
I do. In response to the reception of the photographing start signal, the image signals read from the CCDs of the cameras 12 and 14 undergo predetermined processing in the image processing circuit 20 and then are compressed as necessary, and And the like.

The recording medium can be in various forms such as a memory card and an IC card, and is not limited to a detachable external recording medium but may be a built-in memory. Further, the shooting start signal may be applied from outside the three-dimensional image shooting device 10 such as a remote controller or an externally connected device. When the above-described recording processing is completed, the freeze of the screen is released, and the display returns to the moving image or the intermittent image display.

The image data stored in the memory 30 can be read out under the control of the control device 22.
After the read image data is decompressed, it is output to the monitor 28 via the image processing circuit 20. Thus,
A reproduced image is displayed on the monitor 28. Control device 22
Is a general control of each circuit.
4, 25 and the drive of the slide table 26 are controlled to adjust the direction of the optical axis of the lenses of the cameras 12 and 14 and the lens interval. (A
E), control of auto focus (AF), auto strobe, auto white balance, and the like. The control device 22 controls a corresponding circuit based on various input signals input from a release switch, a mode switch, and other operation units.

In the present embodiment, the brightness of the subject is detected based on the video signals obtained by the cameras 12 and 14, and the exposure control is performed according to the detected brightness. However, a photometric sensor may be separately provided. Further, the control device 22 calculates a focus evaluation value indicating the sharpness of the subject image based on the data received from the image processing circuit 20, and calculates a focus position using the focus evaluation value. Then, the lens control device 18 is controlled in accordance with the calculated focus position to control the cameras 12 and 14.
Focus adjustment.

It should be noted that the autofocus means can take various forms. In addition to the method using the focus evaluation value as described above, a known distance measuring means such as an AF sensor may be used. It is also possible to calculate the subject distance based on the principle of triangulation from the directions of the lens optical axes and the distance between cameras (base line length). FIG. 2 is a graph illustrating an example of a relationship between a convergence angle and a distance between lenses determined according to a subject distance. The control device 22 adjusts the convergence angle and the distance between the lenses in accordance with the object distance detected by the distance measuring means (detecting means) in accordance with the table data as shown in FIG. Is controlled so that

That is, as the subject distance becomes closer, the cameras 12 and 14 are moved in a direction to approach each other, and the distance between the lenses is reduced. However, two cameras 12,
There is a limit to the range in which 14 can be brought closer, and the lens interval cannot be made smaller than the minimum value (dmin) defined by physical constraints such as the size of the camera.
Therefore, when shooting is performed at a shorter distance than the subject distance (L ₁ ) in which the distance between the lenses is set to the minimum value (dmin), the rotation tables 24 and 25 are controlled so as to give a larger convergence angle. I do.

In FIG. 2, in the section from infinity to a predetermined distance value (L ₁ ), the distance between the lenses is gradually reduced, and the convergence angle is gradually (linearly) increased. Not limited to this, the lens optical axis is maintained parallel without giving a convergence angle up to a certain distance value (for example, L ₁ ), and the convergence angle is set when the distance becomes shorter than the specified distance value (L ₁ ). After that, the convergence angle may be adjusted according to the subject distance.

Next, means for correcting distortion of the left and right images in the stereoscopic image pickup apparatus shown in FIG. 1 will be described.
As shown in FIG. 3, when a rectangular subject 32 is photographed by the left and right cameras 12 and 14 with the convergence angle α, an image obtained from each camera 12 is as shown in FIG.
That is, the image (L image) captured by the CCD 12A of the left-eye camera 12 has image distortion in which the right side of the subject 32 is reduced in the vertical direction as shown in the upper left part of FIG.
The image (R image) captured by the CCD 14A of No. 4 has image distortion in which the left side of the subject 32 is reduced in the vertical direction as shown in the upper right part of FIG. In this state, stereoscopic vision is difficult due to image distortion irrelevant to depth.

Therefore, in the present embodiment, these two cameras 12,
In the image processing circuit 20, the image data obtained in step 14 is subjected to a trapezoidal correction for performing a vertical enlargement process in accordance with the pixel position in the horizontal direction of the screen, as shown in the middle part of FIG. Then, as shown in the lower part of FIG. 4, a process of cutting out the corrected image data into a rectangular area (screen) including the subject image is performed. Thus, a left and right image with almost no distortion is obtained.

Next, the operation of the three-dimensional image pickup apparatus configured as described above will be described. FIG. 5 is a flowchart showing the flow of processing in a case where a distance measuring means corresponding to a detecting means for detecting a subject distance is provided independently of the photographing system. First, the distance (L) to the shortest subject to be photographed is measured by the distance measuring means (step S110). Then, based on the measurement result, the base line length (d) and the convergence angle (α) corresponding to the inter-lens distance are obtained by referring to the table data shown in FIG. 2, and the inter-lens distance and the direction of the lens optical axis are obtained. Is adjusted (step S112). Further, based on the subject distance (L) obtained in step S110, the focus of the lens system of each camera 12, 14 is adjusted (step S114).

In this way, the left and right cameras 12 and 14 execute image capture (step S116), and the acquired image data is determined based on L, α, and the lens angle of view (focal length) as described with reference to FIG. An image correction process for reducing distortion is performed (step S118). Thereby, even when the convergence angle (α) is added, the left and right images are not distorted, and natural stereoscopic viewing is possible. Further, conventionally, in order to perform a close-up shooting with the parallel optical axis, the shift amount of the light receiving surface may be large and the image circle may be protruded. However, according to the present invention, the lens system having no room in the image circle However, there is an advantage that it can be used.

FIG. 6 shows two image pickup systems (cameras 12, 1).
An example in which distance measurement is performed by using 4) is shown. This
In the case of, first, the base line length corresponding to the lens interval is set to a predetermined value.
(D ₀) (Step S210), the left and right turtles
Set the optical axes of the lenses 12 and 14 in parallel (step
S212). Then, focus each camera 12,14
Fix to a predetermined position (initial setting position) (Step S2
14).

After setting the initial settings, the two cameras 1
Convergence by changing the direction of the lens optical axis of 2, 14 step by step
While changing the angle by a predetermined amount, the difference between the left and right images is minimized.
Convergence angle (α₀) Is obtained (step S216). So
And the baseline length d₀And convergence angle α ₀To subject distance (L)
By calculation or by referring to table data
(Step S218). Thus, the distance to the shortest subject
After detecting the separation (L), step S1 described in FIG.
Processing similar to the processing of 12 to S118 (step S220)
To S226). This gives the convergence angle (α)
The distortion of the left and right images is corrected even if the
Can be.

Next, a second embodiment of the present invention will be described. In the embodiment described with reference to FIG. 1, an example has been described in which the distortion of the left and right images caused by the convergence angle is corrected by processing the image signal. However, a mode in which image processing is not used is also possible. That is, as shown in FIG. 7, a mode in which the optical axes of the lenses are tilted while the light receiving surfaces of the CCDs 42A and 44A of the two cameras 42 and 44 are kept parallel by using a tilting mechanism. Cameras 42 and 44 used in the second embodiment are provided with optical axes of photographing lenses 46 and 48 and a CCD 42.
Tilt mechanism 5 that can change the relationship between A and 44A with the light receiving surface
2, 54. Although the detailed structure of the tilt mechanism is not shown, each of the cameras 42 and 44 is provided with an electric driving means such as a motor for driving the tilt mechanism, and is controlled via a control device (not shown in FIG. 7). The optical axis directions of the photographing lenses 46 and 48 can be changed in a horizontal plane by the driving force of the electric driving means.

The cameras 42 and 44 are movably supported by a slide table (not shown), and the distance between the lenses can be adjusted according to the subject distance (L), as in the example described with reference to FIG. It has become. According to the stereoscopic image capturing apparatus having such a configuration, even when the convergence angle (α) is changed, the light receiving surfaces of the CCDs 42A and 44A of the left and right cameras 42 and 44 are maintained in parallel, and the distortion is reduced at the image acquisition stage. No left and right images can be acquired. Therefore, correction by image processing is unnecessary.

In the above description, the image light indicating the subject is represented by CC
Although a three-dimensional image capturing apparatus equipped with a camera (electronic camera) that converts an electric signal into an electrical signal using an image capturing means such as D has been described as an example, the present invention relates to a camera that records image light on a photographic film or other photosensitive material ( It can also be applied to a stereoscopic image photographing apparatus using a silver halide camera. Further, in each of the above-described embodiments, an example has been described in which the lens interval and the convergence angle are automatically adjusted according to the subject distance. However, a mode in which the lens interval and the function of adjusting the lens interval are omitted may be employed. Further, the present invention is not limited to a device for capturing a still image,
The present invention can also be applied to a device for shooting a moving image.

[0037]

As described above, according to the three-dimensional image photographing apparatus of the present invention, the means for correcting the image distortion according to the convergence angle is provided. A few high-quality stereoscopic images can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a stereoscopic image photographing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph illustrating an example of a relationship between a convergence angle and a distance between lenses determined according to a subject distance;

FIG. 3 is a diagram showing a state where a subject is photographed by the stereoscopic image photographing apparatus according to the present embodiment;

FIG. 4 is a conceptual diagram used to explain a method for correcting distortion of right and left images.

FIG. 5 is a flowchart showing the flow of processing in a stereoscopic image photographing apparatus provided with a distance measuring means independently of the photographing system.

FIG. 6 is a flowchart showing a flow of processing of a stereoscopic image photographing apparatus for performing distance measurement using two photographing systems (cameras);

FIG. 7 is a main configuration diagram showing a second embodiment of the present invention.

FIG. 8 is a diagram showing a state in which a subject is photographed by a conventional stereoscopic image photographing apparatus.

9 is a diagram showing left and right images acquired by the conventional stereoscopic image photographing device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Stereoscopic imaging apparatus 12, 14, 42, 44, 60, 62 ... Camera 12A, 14A, 42A, 44A ... CCD (imaging means) 16 ... Camera support apparatus 18 ... Lens adjustment apparatus 20 ... Image processing circuit (distortion correction) Means, image signal processing means) 22: control device (control means, second control means) 25: rotary table (convergence angle variable mechanism) 26: slide table (lens interval variable mechanism) 52, 54: tilt mechanism (distortion correction) means)

Claims (11)

[Claims] 1. A three-dimensional image photographing apparatus comprising two cameras, wherein a distortion correcting means for reducing image distortion caused by a convergence angle is provided. 2. A stereoscopic image photographing apparatus comprising two cameras having image pickup means for converting image light into an electric signal, wherein a convergence angle is changed by changing a direction of a lens optical axis of at least one of the cameras. A stereoscopic image, comprising: a convergence angle variable mechanism; and an image signal processing means for processing image signals acquired by the camera, the image signal processing means performing correction for reducing image distortion according to the convergence angle. Shooting equipment. 3. An electric drive means is provided in the convergence angle variable mechanism, a detection means for detecting a distance to a subject, and a control means for controlling the electric drive means in accordance with the subject distance obtained by the detection means. The stereoscopic image photographing apparatus according to claim 2, further comprising: automatically adjusting a convergence angle according to a subject distance. 4. A three-dimensional image photographing apparatus having two cameras, wherein a camera having a tilt mechanism is used, and while the light receiving surfaces of the cameras are kept parallel to each other, a lens optical axis is utilized by using the tilt mechanism. A stereoscopic image photographing apparatus characterized in that the image distortion caused by the angle of convergence is reduced by tilting the camera toward the subject. 5. An electric drive means provided in the tilt mechanism, a detection means for detecting a distance to a subject, and a control means for controlling the electric drive means in accordance with the subject distance obtained by the detection means. 5. The three-dimensional image photographing apparatus according to claim 4, further comprising: automatically adjusting a convergence angle according to a subject distance. 6. A camera having an image pickup means for converting image light into an electric signal is used as the camera, and the convergence angle is reduced by inclining the lens optical axis while keeping the light receiving surfaces of the image pickup means parallel to each other. The three-dimensional image photographing apparatus according to claim 4, wherein the resulting image distortion is reduced. 7. When the distance to the subject is longer than a predetermined distance, the control means maintains the lens optical axes of the two cameras in parallel and shoots a subject at a shorter distance than the predetermined distance. 6. The three-dimensional image photographing apparatus according to claim 3, wherein the electric drive unit is controlled so as to give a convergence angle by tilting a lens optical axis of each camera. 8. The apparatus according to claim 1, further comprising a lens spacing variable mechanism for adjusting a distance between the lenses of the two cameras.
The three-dimensional image photographing device according to claim 1. 9. The three-dimensional image pickup device according to claim 3, further comprising a lens spacing variable mechanism for adjusting a distance between lenses of the two cameras, wherein the lens spacing variable mechanism includes a second lens spacing variable mechanism. A three-dimensional image photographing apparatus comprising: an electric driving unit; and a second control unit that controls the second electric driving unit according to a subject distance obtained by the detection unit. 10. When the subject distance is in a range farther than a predetermined distance value, the lens optical axes of the two cameras are kept parallel to adjust the inter-lens distance according to the subject distance.
10. The stereoscopic image photographing apparatus according to claim 9, wherein when photographing an object closer to the subject than the predetermined distance value, the lens optical axis of each camera is tilted to give a convergence angle. . 11. The detecting means according to claim 1, wherein said detecting means detects a base length corresponding to a distance between the lenses of the two cameras and a convergence angle defined by a direction of a lens optical axis of the camera toward the subject. 6. The three-dimensional image photographing apparatus according to claim 3, further comprising means for calculating a distance.