JP2008085774A - Aberration correcting imaging apparatus and aberration correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aberration correcting imaging apparatus and an aberration correcting method that can satisfactorily correct aberrations of an imaging optical system while suppressing the manufacturing cost, and that can obtain sharp multicolor image information. <P>SOLUTION: The aberration correcting imaging apparatus comprises the imaging optical system 2; an image sensor 21 (imaging element); a drive unit 5 which varies a relative distance between the imaging optical system 2 and image sensor 21 in the optical axis O direction of the imaging optical system 2; and a data processing circuit 25 (image processor) which performs image processing of the image information acquired by the image sensor 21. The data processing circuit 25 is configured to combine pieces of monochromatic image information obtained as to a plurality of reference areas in the optical axis direction of the imaging optical system 2 to generate piece of multicolor image information corresponding to the respective reference areas, and then combines pieces of partial image information cut out of those pieces of multicolor image information to generate complete image information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and an aberration correction method that correct image surface distortion and axial chromatic aberration.

  In an image pickup apparatus including an image pickup optical system, an image formed by the image pickup optical system is affected by aberrations for the following reason.

In the image pickup apparatus, the image formed by the image pickup optical system is affected by the field distortion.
Specifically, the image formed by the imaging optical system is shifted in the optical axis direction depending on the image height (distance from the center of the screen), so even if a flat subject is photographed as it is, it remains on the curved surface. The image will be tied.

  In general, an image sensor that acquires an image formed by an imaging optical system as image information in an imaging apparatus has a flat light receiving surface. For this reason, if the imaging surface of the imaging optical system is curved as described above, for example, one of the subject image obtained at the periphery of the light receiving surface and the subject image obtained at the center is blurred. Therefore, it is difficult to acquire clear image information.

Further, since the refractive index of light slightly differs depending on the wavelength, the light incident on the imaging optical system is refracted at a different angle for each wavelength when passing through a lens constituting the imaging optical system.
For this reason, the position of the imaging plane of the imaging optical system in the optical axis direction of the imaging optical system differs for each wavelength of incident light.

When a subject is photographed under general illumination conditions such as natural light or a normal illumination device, light incident on the imaging optical system from the subject is mixed with light having a plurality of different wavelengths. In this case, the imaging optical system forms images corresponding to the wavelength of the incident light at different positions in the optical axis direction of the imaging optical system (axial aberration).
In general, an image sensor that acquires an image formed by an imaging optical system as image information in an imaging apparatus has a flat light receiving surface. For this reason, the image sensor can acquire clear image information only for the image formed on the light receiving surface.
Therefore, when light of a plurality of different wavelengths is mixed with light incident on the imaging optical system from the subject, the image information obtained by the imaging element includes an image formed at a position different from the light receiving surface. Since the image appears blurred, it is difficult to acquire clear image information.

  As a technique for correcting such on-axis aberrations, for example, a zoom lens described in Patent Document 1 is known. This zoom lens is configured to use a plurality of groups of lenses including an expensive aspherical lens in order to correct the aberration of the spherical lens.

JP 2004-240222 A

However, since the imaging optical system configured by a plurality of groups (sheets) of lenses is expensive, the cost of the imaging apparatus increases. Furthermore, in the imaging optical system that corrects aberrations in this way, the lens design is also complicated, which increases the cost of the imaging apparatus.
Further, even when an imaging optical system configured by a plurality of lenses is used, it is difficult to completely correct aberrations.

  The present invention has been made in view of the above-described circumstances, and is capable of correcting aberrations of an imaging optical system satisfactorily while suppressing manufacturing costs, and capable of acquiring clear multicolor image information. An object is to provide an apparatus and an aberration correction method.

In order to achieve the above object, the present invention provides the following means.
The present invention relates to an imaging optical system, an imaging element that acquires an image formed by the imaging optical system as image information, and a relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system. And changing the relative distance between the image pickup optical system and the image pickup device, and changing the relative distance to obtain image information by the image pickup device. A plurality of control devices, and set according to each of the relative distances from a plurality of pieces of image information acquired by the imaging device by changing the relative distance between the imaging optical system and the imaging device. Obtain multiple pieces of partial image information from which a region has been cut out, obtain multiple pieces of image information for each predetermined wavelength of light, and generate multicolor completed image information by combining these partial image information and image information for each predetermined wavelength Providing an aberration correction image pickup apparatus and a that image processing apparatus.

In the aberration correction imaging apparatus configured as described above, the driving apparatus can change the relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system.
In this aberration-correcting imaging apparatus, when photographing a subject, a plurality of images are obtained by changing the relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system within a range in which at least a part of the image information is in focus. Get image information.
Specifically, in this aberration correction imaging apparatus, the relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system is made to correspond to the shift of the imaging position for each wavelength of light of the imaging optical system. Thus, the image information is acquired by the imaging element in a state where the relative distances are sequentially set for the respective wavelengths.

For example, in a state where the relative distance between the imaging optical system and the imaging element is matched with the focal length of the imaging optical system corresponding to red light among the three primary colors of light, red, green, and blue, An image with red light is formed. In this state, other color images (green light image and blue light image) appear blurred on the image sensor. In this state, by acquiring image information with respect to only the red light image by the imaging element, single-color image information in which the red light image is in focus can be obtained.
By performing the same operation for the light of the remaining three primary colors, the single-color image information in which the green light image is in focus and the single-color image information in which the blue light image is in focus are obtained. can get.

Here, as a method of acquiring image information only with respect to light of an arbitrary color by the image sensor, all light incident on the image sensor is limited to monochromatic light using an optical filter that passes only light of a specific color. Monochromatic image information can be acquired by acquiring image information using an image sensor.
In addition, the imaging element is an aggregate of a plurality of types of light receiving elements having different wavelengths of light that can be detected, and image information is generated based only on detection signals of the same type of light receiving elements, so that monochrome image information can be obtained. Can be acquired.

In this way, by acquiring image information individually for monochromatic light in a state in which the relative distance between the imaging optical system and the imaging element is matched with the focal length of light of each wavelength (color), axial chromatic aberration is obtained. It is possible to obtain clear single-color image information that minimizes the influence of.
The image processing apparatus generates multicolor image information that minimizes the influence of axial chromatic aberration by combining a plurality of single-color image information obtained in this way.
As described above, this aberration-correcting imaging apparatus can obtain clear multicolor image information that is not affected by the axial chromatic aberration even if the imaging optical system has the axial chromatic aberration. In other words, this chromatic aberration correction imaging apparatus can correct axial chromatic aberration and obtain clear multicolor image information without making the imaging optical system complicated.

As the multicolor image information obtained in this way, for example, the first multicolor image information in which only the center portion of the subject is in focus, and the second color in which only the peripheral portion of the subject is in focus. Multicolor image information is obtained.
The image processing apparatus obtains only a region (a region in focus) according to the relative distance in the optical axis direction between the imaging optical system and the imaging element from the plurality of multicolor image information obtained in this way. Cut out to obtain partial image information.

The image processing device generates clear image information (completed image information) that is in focus from the center to the peripheral portion of the subject by combining the partial image information.
That is, this aberration-correcting imaging apparatus can obtain clear image information that is in focus from the center to the peripheral part of the subject even when the imaging optical system has image surface distortion. In other words, this aberration-correcting imaging apparatus corrects image surface distortion aberration without making the imaging optical system complicated, and is a clear image that is in focus from the center to the periphery of the subject. Information can be obtained.

Here, the focused area in the multicolor partial image information is determined by the characteristics of the image plane distortion of the imaging optical system and the relative distance in the optical axis direction between the imaging optical system and the imaging element.
For this reason, based on the characteristics of the image plane distortion of the imaging optical system, the imaging optical system is configured so that the overlapping of the in-focus areas between the multicolor partial image information acquired in each imaging is minimized. By determining the relative distance between the image sensor and the number of times of acquisition of the image information (i.e., the number of reference positions), clear image information that is in focus from the center to the periphery of the subject is obtained. It can be acquired with the minimum number of acquisitions.

  The control device controls the operation of the driving device to sequentially position the imaging device in a plurality of reference regions in the optical axis direction of the imaging optical system, and controls the operation of the imaging device, The image information in a state of being located in the reference area is acquired, and in the acquisition of the image information in the reference area, the operation of the driving device is controlled, and the relative distance between the imaging optical system and the imaging element is determined. The focal length for each predetermined wavelength of light of the imaging optical system is sequentially set, and the relative distance between the imaging optical system and the imaging element is set to each focal length for each predetermined wavelength of light of the imaging optical system. In such a state, the image information may be acquired by the image sensor.

In this case, the control device automatically adjusts the relative distance between the image pickup optical system and the image pickup device and performs shooting using the image pickup device, so that the user can easily perform operations without performing complicated operations. The completed image information can be obtained.
Specifically, in this aberration correction imaging apparatus, relative distances between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system, respectively, with respect to reference regions set at a plurality of locations in the optical axis direction of the imaging optical system. The image information is acquired by the image pickup device in a state where the image pickup position is sequentially set to a different relative distance for each wavelength corresponding to the shift of the imaging position for each wavelength of the light of the image pickup optical system.
Each reference area is set in a range where the image information acquired by the imaging element is in focus in the optical axis direction of the imaging optical system.

In this way, by acquiring image information individually for monochromatic light in a state in which the relative distance between the imaging optical system and the imaging element is matched with the focal length of light of each wavelength (color), axial chromatic aberration is obtained. It is possible to obtain clear single-color image information that minimizes the influence of.
The image processing device generates multicolor image information (completed image information) that minimizes the influence of axial chromatic aberration for each reference region by combining a plurality of single color image information obtained in this way. To do.

The image processing apparatus cuts out only the area (the area in focus) corresponding to the relative distance in the optical axis direction between the imaging optical system and the imaging element from the multicolor image information obtained in this way. Get partial image information.
The image processing apparatus combines the partial image information to generate clear multicolor image information (completed image information) that is in focus from the center to the periphery.

The image processing device may be configured to generate the multi-color image information corresponding to the adjacent reference region using one or more common single-color image information.
In this case, when generating multi-color image information corresponding to the reference region, one or more single-color image information corresponding to the adjacent reference region is used.
As a result, the number of pieces of image information to be acquired can be reduced as compared with the case of generating monochrome image information and multicolor image information for each reference region. For this reason, it is possible to reduce the time required from the start of imaging to the generation of completed image information.

  The present invention is also an aberration correction method in an imaging apparatus having an imaging optical system and an imaging element that acquires an image connected by the imaging optical system as image information, and the optical axis direction of the imaging optical system Changing the relative distance between the image pickup optical system and the image pickup device, changing the relative distance between the image pickup optical system and the image pickup device, and acquiring the image information by the image pickup device a plurality of times. From the plurality of image information acquired by changing the relative distance between the optical system and the imaging element, image information of a predetermined wavelength of light is obtained for each of the plurality of reference regions in the optical axis direction of the imaging optical system. The image information of a predetermined wavelength of the light is combined to generate multicolor image information corresponding to each reference region, and the multicolor image information corresponds to each of the multicolor image information. Reference area To obtain partial image information cut out an image area that is set in accordance with the relative distance, providing aberration correction method for generating a finished image information by combining these partial image information.

In this aberration correction method, when photographing a subject, a plurality of pieces of image information are photographed by changing the relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system.
Specifically, in this aberration correction method, the relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system is determined for each of the reference regions set at a plurality of locations in the optical axis direction of the imaging optical system. Then, image information is acquired by the imaging element in a state where the relative positions are sequentially set differently for each wavelength in correspondence with the shift of the imaging position for each wavelength of the light of the imaging optical system.
Each reference area is set in a range where the image information acquired by the imaging element is in focus in the optical axis direction of the imaging optical system.

  By acquiring image information that is individually focused on monochromatic light in this way, a plurality of clear monochromatic image information that minimizes the influence of axial chromatic aberration can be obtained.

By combining a plurality of pieces of single-color image information obtained in this way, multi-color image information (completed image information) is generated for each reference region, which minimizes the influence of axial chromatic aberration.
That is, with this aberration correction method, even if the imaging optical system has axial chromatic aberration, clear multicolor image information that is not affected by axial chromatic aberration can be obtained. In other words, in this aberration correction method, it is possible to correct axial chromatic aberration and obtain clear multicolor image information without making the imaging optical system complicated.

The plurality of multicolor image information obtained in this way have different distances from the image center (position facing the optical axis of the imaging optical system) to the focused area. For example, when two reference areas are set, the first multicolor image information in which only the center portion of the subject is in focus and the second multicolor image information in which only the peripheral portion of the subject is in focus are can get.
From the multicolor image information obtained in this way, partial image information is obtained by cutting out only the region (the focused region) corresponding to the relative distance in the optical axis direction between the imaging optical system and the imaging device. .

By combining these pieces of partial image information, clear multi-color image information (completed image information) that is in focus from the center to the periphery of the subject is generated.
That is, in this aberration correction method, even if the imaging optical system has image surface distortion, clear image information that is in focus from the center to the periphery of the subject can be obtained. In other words, in this aberration correction method, clear image information in which the image plane distortion is corrected and the entire object is in focus from the center of the subject to the periphery without using a complicated configuration of the imaging optical system. Can be obtained.

In this aberration correction method, the multi-color image information corresponding to the adjacent reference region may be generated using one or more common single-color image information.
In this case, when generating multi-color image information corresponding to the reference region, one or more single-color image information corresponding to the adjacent reference region is used.
As a result, the number of pieces of image information to be acquired can be reduced as compared with the case of generating monochrome image information and multicolor image information for each reference region. For this reason, it is possible to reduce the time required from the start of imaging to the generation of completed image information.

  According to the aberration correction imaging apparatus and the aberration correction method according to the present invention, while simplifying the configuration of the imaging optical system and suppressing the manufacturing cost, the aberration of the imaging optical system is corrected well to obtain clear multicolor image information. Can be acquired.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Here, an example in which the present invention is applied to a digital still camera will be described.
As shown in the block diagram of FIG. 1, the digital still camera 1 (aberration correction imaging apparatus) according to the present embodiment displays an image obtained by connecting the imaging optical system 2 and the imaging optical system 2 in a housing (not shown). The imaging function unit 3 acquired as information and an image information display panel that displays various image information such as image information acquired by the imaging function unit 3 are provided.

Here, the imaging optical system 2 may be configured by only one spherical convex lens, or may be configured by a lens unit including a plurality of lenses including a spherical lens. As the imaging optical system 2, a zoom optical system may be used, or a lens unit having a minimum number of lenses may be used in which a lens having a function of correcting axial aberration is omitted.
In addition, as the image information display panel, for example, an LCD (Liquid Crystal Display) panel or an organic or inorganic EL (electroluminescence) display panel can be used. In the present embodiment, the LCD panel 4 is used as the image information display panel.

The imaging function unit 3 is provided with a driving device 5 that changes a relative position between an image sensor 21 (imaging device), which will be described later, and the housing in the optical axis O direction of the imaging optical system 2.
The drive device 5 changes the relative distance between the image pickup optical system 2 and the image sensor 21 in the optical axis O direction by changing the relative position between the image sensor 21 and the housing. The drive device 5 can be configured by an arbitrary mechanism such as an actuator using a piezoelectric element or MEMS (Micro Electro Mechanical Systems) in addition to a screw feed mechanism and a cylinder mechanism.

Hereinafter, a detailed configuration of the imaging function unit 3 will be described.
The imaging function unit 3 includes a power supply unit PW that supplies power to each device constituting the digital still camera 1, a CPU (Central Processing Unit), and the like, and a system controller 20 that controls each unit of the digital still camera 1 ( Control device), a ROM 20a in which a control sequence program for controlling the operation of the system controller 20, various control parameters, and the like, and data necessary for the execution of the various sequences by the system controller 20 are temporarily stored. And a RAM 20b used as a work area.

The system controller 20 controls the operation of the power supply unit PW to control the supply of power to each device constituting the imaging apparatus main body 2.
When the power state of the imaging apparatus main body 2 is turned on, the system controller 20 reads programs, parameters, and the like from the ROM 20a and performs predetermined processing. As a result, the system of the digital still camera 1 is activated and is in a state where it can be electrically photographed.

A flat image sensor 21 (imaging device) is disposed behind the imaging optical system 3. Thereby, a subject image is formed on the flat light receiving area of the image sensor 21 by the imaging optical system 3.
As the image sensor 21, an arbitrary one such as one using a CCD (Charge Coupled Devices) or one using a CMOS (Complementary Metal Oxide Semiconductor) can be used. In addition, a global shutter type high-speed CMOS sensor, a high-speed CMOS sensor in which single-slope A / D converters are integrated for each pixel column, and the like can be used. In the present embodiment, an image sensor using a CCD is used as the image sensor 21.

The imaging apparatus main body 2 is provided with a CCD driver 22 that drives the image sensor 21. Thereby, the image sensor 21 converts the optical subject image obtained via the imaging optical system 3 into an electrical imaging signal and outputs the electrical imaging signal.
The imaging apparatus main body 2 is provided with an amplifier 23 that amplifies an imaging signal output from the image sensor 21 and an A / D converter 24 that digitally converts the output of the amplifier 23.

Small light receiving elements are arranged in a matrix on the light receiving surface of the image sensor 21. Each light receiving element is provided with a micro micro color filter corresponding to one of red (R), green (G), and blue (B). An imaging signal serially output for each color corresponding to each micro color filter from each light receiving element of the image sensor 21 is amplified to an appropriate level by an amplifier 23 and then digitally converted by an A / D converter 24. , Red, green, and blue image data.
The CCD has a disk-shaped color rotation filter provided with a plurality of different filter portions in the circumferential direction in addition to the CCD using the color separation method of the color CCD method using the above-described micro color filter. It is possible to use a color filter switching type CCD that performs color separation of light incident on the light receiving surface by rotating the color rotation filter and switching a filter portion that covers the light receiving surface of the CCD.

  The imaging apparatus body 2 is processed by a data processing circuit 25 (image processing apparatus) that performs various data processing such as white balance adjustment and gamma correction on the image data obtained by the image sensor 21, and the data processing circuit 25. And an LCD driver 26 for displaying the image data on the LCD panel 4 as image information. When the imaging apparatus main body 2 is in the photographing mode, the image data from the A / D converter 24 is input to the data processing circuit 25, and one image on which necessary processing has been performed by the data processing circuit 25. Minute image data is sent to the LCD driver 26 one after another. As a result, the subject image being shot is displayed on the LCD panel 4 as a moving image. In the shooting mode, the system controller 20 can switch between a display mode in which an image being shot by the image sensor 21 is displayed on the LCD panel 4 and a non-display mode in which the image being shot is not displayed on the LCD panel 4. It can be done.

  The imaging apparatus body 2 is provided with an AE processing circuit 27 that performs automatic exposure control (AE control) during imaging. Image data from the data processing circuit 25 is also sent to the AE processing circuit 27. This AE processing circuit 27 is based on each input image data and the charge accumulation time of the image sensor 21 set in the CCD driver 22 at that time, that is, the shutter time of the electronic shutter. A luminance photometric value is calculated. Then, the system controller 20 determines the shutter time of a new electronic shutter based on this photometric value, and feeds back this shutter time to the CCD driver 22, whereby the drive of the image sensor 21 is adjusted, and AE Control is performed.

  As described above, the digital camera 1 measures subject luminance by a TTL (Through The Lens) photometry method using the image sensor 21 as a light receiving sensor. The aperture value may be changed with the shutter time of the electronic shutter. When changing the aperture value, it goes without saying that the photometric value corresponding to the subject brightness is calculated with the aperture value taken into account.

The imaging apparatus main body 2 is provided with an external storage device that records the image data output from the data processing circuit 25. In the present embodiment, a flash memory 28 is used as an external storage device. The flash memory 28 is provided so as to be detachable from the imaging apparatus main body 2.
The imaging apparatus main body 2 is provided with an I / O port 31 for exchanging data between the system controller 20 and other devices. Connected to the I / O port 31 are an input unit 32 that accepts user input and an external connection terminal group 33 to which external devices are connected.

  The input unit 32 includes, for example, a release switch, a zoom lever, a key operation unit, and the like, and signals corresponding to these operations are input to the system controller 20 via the I / O port 31. The system controller 20 performs various processes and controls according to the input signal. The external connection terminal group 33 includes a memory slot into which a memory card as an external storage device is mounted, a connector for connecting to an external computer, and the like. Data can be input / output through the I / O port 31 by connecting an external storage device or computer to the external connection terminal group 33.

  Here, in the reproduction mode, the system controller 20 displays image data to be displayed from the flash memory 28 or the external storage device connected to the external connection terminal group 33 based on a user instruction input to the input unit 32. Is sent to the data processing circuit 25. As a result, the image data to be displayed is sent to the LCD driver 26 and an image is displayed on the LCD panel 4.

The details of the photographing operation of the digital still camera 1 will be described below with reference to the flowchart of FIG.
[Movement to the first reference area]
When a shooting command is input from the user via the input unit 32, the system controller 20 operates a lens driving device (not shown) on the imaging optical system 2 at an arbitrary zoom position, thereby taking the imaging optical system. 2 and the image sensor 21 are adjusted (step SA1). Specifically, the relative distance between the imaging optical system 2 and the image sensor 21 in the optical axis O direction of the imaging optical system 2 is adjusted, and the light receiving surface of the image sensor 21 is set to the optical axis O direction of the imaging optical system 2. Are located in any one of the plurality of reference areas A1, A2,. In the present embodiment, the system controller 20 positions the light receiving surface of the image sensor 21 within the first reference area A1.

Here, each reference area is within a range in which at least a part of the area including the subject P (see FIG. 5) on the light receiving area of the image sensor 21 is in focus in the optical axis O direction of the imaging optical system 2. Is set.
As shown in FIG. 3, the imaging plane F of the imaging optical system 2 is a curved surface due to the influence of the image plane distortion. In the present embodiment, out of the movement range of the image sensor 21 in the direction of the optical axis O of the imaging optical system 2, the range in focus in the region corresponding to the center portion of the light receiving surface in the image information acquired by the image sensor 21 is the first. A range that is in focus in a region corresponding to the peripheral portion of the light receiving surface in the image information acquired by the image sensor 21 is defined as a second reference region A2.
Next, the zoom position of the imaging optical system 2 is detected (step SA2). Then, from the detected zoom position and the lens configuration of the imaging optical system 2, the number of times (2 to n times) at which an optimal subject image is obtained in accordance with the curvature state of the image plane calculated in advance is determined, The moving direction and the operation amount of the image sensor 21 are determined (step SA3).

[First multicolor image information acquisition operation]
With the light receiving surface of the image sensor 21 positioned in the first reference area A1, the system controller 20 issues an operation command to the CCD driver 22 to perform a predetermined photographing operation to be described later. First-time multicolor image information is acquired (step SA4).
In this state, image information focused on at least a part of the subject P on the light receiving area is obtained.

[Movement to the second reference area]
When the acquisition of the first multicolor image information is completed, the system controller 20 operates the driving device 5 to display the previous multicolor image information in the region including the subject P on the light receiving area of the image sensor 21. The relative distance between the imaging optical system 2 and the image sensor 21 is changed so as to focus on an area different from the image information obtained at the time of acquisition (step SA5). Specifically, the relative distance between the image pickup optical system 2 and the image sensor 21 in the direction of the optical axis O of the image pickup optical system 2 is adjusted, and the light receiving surface of the image sensor 21 is positioned in the second reference area A2. .

[Second Multicolor Image Information Acquisition Operation]
In this state, the system controller 20 issues an operation command to the CCD driver 22 to perform a predetermined photographing operation, and acquires second multicolor image information (step SA6).
In this state, multicolor image information in focus in a region different from the image information obtained when the first multicolor image information is acquired among the subjects P on the light receiving area is obtained.

  Thereafter, the system controller 20 repeats the relative position adjustment operation and the image capturing operation until images in focus are captured for all regions including the subject P on the light receiving area of the image sensor 21 (step SAn). , SAn + 1).

In the present embodiment, two areas of the first reference area A1 and the second reference area A2 are set as the reference areas.
In this case, in the first multicolor image information acquisition operation, as shown in FIG. 4, for example, by setting the relative distance between the imaging optical system 2 and the image sensor 21 to D1, as shown in FIG. First multi-color image information GC1 is obtained in which only the central portion P1 of the area including the subject P on the area is in focus. In the actual first multicolor image information acquisition operation, multicolor image information GC1 corresponding to the first reference area A1 is obtained based on a plurality of single-color image information, as will be described later.
Further, in the second multicolor image information acquisition operation, as shown in FIG. 6, for example, by setting the relative distance between the imaging optical system 2 and the image sensor 21 to D2, as shown in FIG. Second image information G2 is obtained in which only the peripheral edge P2 of the region including the subject P is in focus. In the actual second multicolor image information acquisition operation, as described later, multicolor image information GC2 corresponding to the second reference region A2 is obtained based on a plurality of single color image information.

  Next, the system controller 20 controls the operation of the data processing circuit 25, and from the multicolor image information obtained in each multicolor image information acquisition step, the optical axis O direction between the imaging optical system 2 and the image sensor 21. Only a region corresponding to the relative distance (region in focus) is cut out to obtain partial image information (step SAn + 2). Specifically, the data processing circuit 25 cuts out only the central portion P1 from the first multicolor image information GC1, and cuts out only the peripheral portion P2 from the second multicolor image information GC2, respectively. Let it be image information.

Here, the relationship between the relative distance between the imaging optical system 2 and the image sensor 21 in the direction of the optical axis O and the focused area in the obtained image information is the optical characteristic of the imaging optical system 2 (imaging optical system 2). (Field curvature characteristic calculated from the lens data), the optical characteristic at the zoom position at the time of shooting in the zoom optical system, the angle of view of the subject, and the like. Of the image information obtained by one multicolor image information acquisition operation, the focused area is concentrically divided from the center of the screen to the peripheral edge of the screen depending on the image plane distortion of the imaging optical system 2. In some cases, it may be one of the regions, but there may be a case where a plurality of regions out of the regions concentrically divided from the center of the screen to the periphery of the screen are in focus. In this way, when a plurality of areas are in focus, each of the in-focus areas can be cut out from the image information, and each can be used as partial image information.
Based on this information, the system controller 20 identifies the in-focus area of the multicolor image information obtained in each multicolor image information acquisition step, and sends the partial image information to the data processing circuit 25. Generate.

Thereafter, the system controller 20 controls the operation of the data processing circuit 25 to synthesize the obtained partial image information, and a clear multicolor image in which the entire focus is achieved from the center to the peripheral portion of the subject. Information (completed image information) is generated. Specifically, as shown in FIG. 7, the data processing circuit 25 synthesizes the central portion P1 of the first multicolor image information GC1 and the peripheral portion P2 of the second multicolor image information GC2. Thus, multi-color image information GC3 is generated in which the central portion is the region P1 of the first multi-color image information GC1 and the peripheral portion is the region P2 of the second multi-color image information GC2.
In addition, in each partial image information, the partial image information of the adjacent region and the information of the boundary portion of the region are partially overlapped for convenience of the synthesis process. And when combining each partial image information, the overlapping parts are mixed in the partial image information of an adjacent area | region. Specifically, in each partial image information, in the vicinity of the boundary with the adjacent region, the usage ratio of the partial image information is lower as the portion is closer to the adjacent region, and the usage ratio of each partial image is half on the boundary. Is set to be As a result, the seam of the image information at the boundary portion between adjacent regions becomes inconspicuous.

That is, in the digital still camera 1, even if the image pickup optical system 2 has image surface distortion, it is possible to obtain clear multicolor image information that is in focus from the center to the periphery of the subject. Can do. In other words, the digital still camera 1 corrects the image plane distortion without making the imaging optical system 2 complicated, and is in sharp focus from the center to the periphery of the subject. Multicolor image information can be obtained.
Thus, according to the digital still camera 1, the configuration of the imaging optical system 2 is simplified to reduce the manufacturing cost, and the image surface distortion of the imaging optical system 2 is corrected well, and the peripheral portion from the center of the subject is corrected. Until then, clear image information can be obtained.

Hereinafter, the photographing operation in each reference region (operation when acquiring multicolor image information in each multicolor image information acquisition step) of the digital still camera 1 according to the present embodiment will be described.
[First relative position adjustment]
The system controller 20 operates the driving device 5 to finely adjust the relative distance between the imaging optical system 2 and the image sensor 21 when acquiring image information in each reference region (step SB1). Specifically, the relative distance between the image pickup optical system 2 and the image sensor 21 in the direction of the optical axis O of the image pickup optical system 2 is one of the wavelength ranges of light to be included in the image information acquired by the digital still camera 1. The focal length of the imaging optical system 2 with respect to the wavelength range of the part is matched.

[First shot]
In this state, the system controller 20 issues an operation command to the CCD driver 22 and performs first shooting (step SB2).
In the present embodiment, image data for one color of, for example, red, green, and blue is acquired based on a photographing signal serially output for each color corresponding to each microfilter from each light receiving element of the image sensor 21.
In this state, monochromatic image information corresponding to a part of the wavelength range of light desired to be included in the image information acquired by the digital still camera 1 is obtained.

[Second relative position adjustment]
When the first shooting is completed, the system controller 20 operates the driving device 5 to change the relative distance between the imaging optical system 2 and the image sensor 21 (step SB3). Specifically, the relative distance between the image pickup optical system 2 and the image sensor 21 in the direction of the optical axis O of the image pickup optical system 2 is the first of the wavelength ranges of light to be included in the image information acquired by the digital still camera 1. The focal length of the imaging optical system 2 is made to correspond to light in a wavelength region corresponding to one color in another RGB different from that at the time of the relative position adjustment.

[Second shot]
In this state, the system controller 20 issues an operation command to the CCD driver 22 and performs the second shooting (step SB4).
In this state, monochromatic image information corresponding to a part of the wavelength range different from the image information obtained at the time of the first imaging among the wavelength range of light to be included in the image information acquired by the digital still camera 1 is obtained. .

Thereafter, the system controller 20 repeats the relative position adjustment operation and the photographing operation until image information corresponding to the entire wavelength range of light desired to be included in the image information acquired by the digital still camera 1 is acquired (steps SBn, SBn + 1). ).
Thus, by acquiring image information individually for monochromatic light, clear monochromatic image information that minimizes the influence of axial chromatic aberration can be obtained.

Data acquisition is repeated corresponding to another color in RGB (if the color tone that can be detected by the image sensor 21 is decomposed into RGB or higher color tone, the remaining color is decomposed).
Here, the imaging position of light of each wavelength by the imaging optical system 2 varies depending on the lens configuration of the imaging optical system 2 and the zoom position. The imaging positions of light of these wavelengths can be calculated in advance from characteristic data such as the lens configuration of the imaging optical system 2.
In order to minimize the time required for the shooting operation, it is preferable to determine the order of acquiring the light of each wavelength so that the amount of movement of the image sensor 21 during shooting is minimized.
FIG. 10 shows an example of the image acquisition order. Here, in the example shown in FIG. 10, an image for each color is formed on the optical axis O of the imaging optical system 2 in the order of B, G, and R from the object side. In FIG. 10, the distance from the position where the B image is formed to the position where the G image is formed is D1, and the distance from the position where the G image is formed to the position where the R image is formed. The distance is D2, and the distance from the light receiving surface of the image sensor 21 to the position where the G image is formed is α. Further, D2> D1, α <D2, and D2-D1> 2α.
Under this condition, the light receiving surface of the image sensor 21 is moved to the position where the G image is formed during the first imaging, and the B image is formed during the second imaging. By moving to the position where the image sensor 21 is moved and moving to the position where the R image is formed at the time of the third imaging, the amount of movement of the image sensor 21 at the time of shooting is minimized.

In this embodiment, the digital still camera 1 is configured to acquire image information for the entire light in the visible light range.
Specifically, in the first relative position adjustment, as shown in FIG. 11, the relative distance between the imaging optical system 2 and the image sensor 21 in the optical axis O direction of the imaging optical system 2 is set to the imaging optical for red light. It is made to coincide with the focal length DR of the system 2. In this state, since the light receiving surface of the image sensor 21 and the imaging surface of red light by the imaging optical system 2 coincide with each other, an image of only red light is clearly formed on the light receiving surface.
In the first shooting, the system controller 20 controls the operation of the data processing circuit 25 to extract only red image data from the image data output from the A / D converter 24 to the data processing circuit 25. Thereby, monochromatic image information corresponding to red light is obtained.

In the second relative position adjustment, as shown in FIG. 12, the relative distance between the imaging optical system 2 and the image sensor 21 in the direction of the optical axis O of the imaging optical system 2 is set to the focal length of the imaging optical system 2 with respect to green light. Match DG. In this state, the light receiving surface of the image sensor 21 and the green light image forming surface by the image pickup optical system 2 coincide with each other, so that an image of only the green light is clearly formed on the light receiving surface.
In the second shooting, the system controller 20 controls the operation of the data processing circuit 25 to extract only green image data from the image data output from the A / D converter 24 to the data processing circuit 25. Thereby, monochromatic image information corresponding to green light is obtained.

In the third relative position adjustment, as shown in FIG. 13, the relative distance between the imaging optical system 2 and the image sensor 21 in the direction of the optical axis O of the imaging optical system 2 is set as the focal length of the imaging optical system 2 with respect to blue light. Match to DB. In this state, the light receiving surface of the image sensor 21 and the blue light image formation surface by the imaging optical system 2 coincide with each other, so that an image of only blue light is clearly formed on the light reception surface.
In the third shooting, the system controller 20 controls the operation of the data processing circuit 25 to extract only blue image data from the image data output from the A / D converter 24 to the data processing circuit 25. Thereby, monochromatic image information corresponding to blue light is obtained.

  Here, the relationship between the relative distance in the optical axis O direction between the imaging optical system 2 and the image sensor 21 and the focused area in the obtained image information is obtained in advance based on the optical characteristics of the imaging optical system 2. be able to. Based on this information, the system controller 20 determines the relative distance between the imaging optical system 2 and the image sensor 21 in the optical axis O direction of the imaging optical system 2 in each relative position adjustment.

Next, the system controller 20 controls the operation of the data processing circuit 25 and combines the obtained single color image information to generate multicolor image information (completed image information) (step SBn + 2).
As described above, in each shooting, clear image information can be obtained in which the influence of axial chromatic aberration is minimized. By synthesizing such clear single-color image information, clear multicolor image information can be obtained in which the influence of axial chromatic aberration is minimized.

  That is, in the digital still camera 1, even if the imaging optical system 2 has axial chromatic aberration, the axial chromatic aberration is corrected well to obtain clear multicolor image information corresponding to each reference region. be able to. In other words, the digital still camera 1 can correct axial chromatic aberration and obtain clear multicolor image information corresponding to each reference region without making the imaging optical system 2 complicated. .

In the digital still camera 1, as described above, completed image information is generated based on clear multicolor image information corresponding to each reference region in which the axial chromatic aberration is well corrected.
As a result, according to the digital still camera 1, while simplifying the configuration of the imaging optical system 2 and reducing the manufacturing cost, the image surface distortion aberration and the axial chromatic aberration of the imaging optical system 2 are corrected satisfactorily. Completed image information (multicolor image information) can be acquired.

  In the digital still camera 1, the system controller 20 automatically adjusts the relative distance between the imaging optical system 2 and the image sensor 21, and photographing with the image sensor 21. The completed image information can be easily obtained without performing any operation.

  Hereinafter, an operation of correcting the correction of the image plane distortion and the correction of the axial chromatic aberration described so far will be described with reference to FIG. Here, FIG. 14A is a diagram showing the positional relationship of the reference regions in the optical axis O direction of the imaging optical system 2, and FIG. 14B is an image sensor of an image obtained in each reference region. FIG.

  As shown in FIG. 14A, the imaging surface F of the imaging optical system 2 has a curved surface that is concave on the object side (left side of the paper in FIG. 14A) due to the influence of the image surface distortion. . In the present embodiment, in the optical axis O direction of the imaging optical system 2, the range in focus at the center P1 ′ of the region including the subject in the light receiving surface of the image sensor 21 is defined as the first reference region A1 ′, and the light receiving surface. The second reference area A2 ′ is a range in focus at the middle portion P2 ′ of the area including the subject, and the third reference area is a range in focus at the peripheral edge portion P3 ′ of the area including the subject on the light receiving surface. A3 '.

  Further, in the imaging optical system 2 shown in the present embodiment, as shown in FIG. 14A, due to the influence of axial chromatic aberration, B, G, and R from the object side on the optical axis O of the imaging optical system 2 are obtained. An image for each color is formed in order. That is, in the imaging optical system 2 shown in the present embodiment, the image formation corresponding to the image formation planes FG and R corresponding to B in order from the object side along the optical axis O direction. The surface FR is located.

Under this condition, by moving the light receiving surface of the image sensor 21 to the position B1 where the B image in the first reference area A1 ′ is formed, the central portion of the area including the subject with respect to the B wavelength is obtained. Image information focused on P1 ′ is obtained.
Next, by moving the light receiving surface of the image sensor 21 to the position G1 where the G image in the first reference area A1 ′ is formed, the central portion P1 ′ of the area including the subject with respect to the G wavelength. Image information in focus is obtained.
Next, by moving the light receiving surface of the image sensor 21 to a position R1 where an R image is formed in the first reference area A1 ′, the center P1 ′ of the area including the subject with respect to the R wavelength is formed. Image information in focus is obtained.

Next, by moving the light receiving surface of the image sensor 21 to the position B2 where the B image in the second reference area A2 ′ on the optical axis O is formed, the area of the object including the subject with respect to the B wavelength is obtained. Image information focused on the intermediate portion P2 ′ is obtained.
Next, by moving the light receiving surface of the image sensor 21 to the position G2 where the G image in the second reference region A2 ′ on the optical axis O is formed, the region including the subject with respect to the G wavelength. Image information focused on the intermediate portion P2 ′ is obtained.
Next, by moving the light receiving surface of the image sensor 21 to a position R2 where the R image in the second reference area A2 ′ on the optical axis O is formed, an area including the subject with respect to the R wavelength. Image information focused on the intermediate portion P2 ′ is obtained.

  Further, in the same manner as described above, the images of the positions B3 and G where the image of B in the third reference area A3 ′ on the optical axis O is formed are formed on the light receiving surface of the image sensor 21. By moving to the position R3 where the images of the positions G3 and R are formed, the respective wavelengths of R, G and B in the third reference area A3 ′ are focused on the peripheral part P3 ′ of the area including the subject. Can be obtained.

  Next, the image sensor 21 is moved to a total of nine places as described above, and each of B, G, R divided into the respective regions of the central portion P1 ′, the intermediate portion P2 ′, and the peripheral portion P3 ′ is obtained. By appropriately combining the image data of the image formed with respect to each wavelength, it becomes possible to obtain a good multicolor entire image in which the image surface distortion and the axial chromatic aberration are well corrected.

In the above description, the image data is acquired by moving the image sensor 21 to a total of nine locations in order to acquire image information for each region of the central portion P1 ′, the intermediate portion P2 ′, and the peripheral portion P3 ′. An example to do is shown.
The present invention is not limited to this, but is a region set according to each relative distance from a plurality of pieces of image information acquired by the image sensor 21 by changing the relative distance between the imaging optical system 2 and the image sensor 21. A plurality of partial image information obtained by cutting out image information of a plurality of wavelengths in a state where the imaging optical system 2 and the image sensor 21 are positioned at a relative distance at which at least one partial image information is acquired. Multi-color completed image information can be generated by combining partial image information.
Specifically, in FIG. 14, by positioning the light receiving surface of the image sensor 21 at the point B1 on the optical axis O, an image of B wavelength at the central portion P1 ′ and image data of R wavelength at the intermediate portion P2 ′. Can be acquired in a batch.
With this configuration, it is possible to obtain a multicolored completed image at a high speed while minimizing the amount of movement of the image sensor 21.

Here, in the above embodiment, a plurality of single-color image information is acquired for each reference region, and the data processing circuit 25 obtains multicolor image information corresponding to each reference region based on the single-color image information. An example in which the configuration is generated has been described.
The present invention is not limited to this, and some monochromatic image information is not acquired for one of the adjacent reference areas, and the data processing circuit 25 corresponds to the one reference area. When generating multi-color image information, instead of image information of a color that has not been acquired, it corresponds to a color that has not been acquired in one reference region, out of single-color image information acquired in an adjacent reference region. It may be configured to use monochromatic image information.
As described above, when generating multi-color image information corresponding to the reference region, by using one or more single-color image information corresponding to the adjacent reference region, it is possible to obtain single-color image information for each reference region. The number of pieces of image information to be acquired can be reduced as compared with the case of generating and generating multicolor image information. For this reason, it is possible to reduce the time required from the start of imaging to the generation of completed image information.

In the above embodiment, an example in which the driving device 5 that changes the relative position of the image sensor 21 with respect to the housing is used as the driving device that changes the relative distance between the imaging optical system 2 and the image sensor 21. However, the present invention is not limited to this, and a driving device having a configuration in which the relative distance between the imaging optical system 2 and the image sensor 21 is changed by changing the relative position of the imaging optical system 2 with respect to the housing is used. May be.
In the above embodiment, the example in which the present invention is applied to a digital still camera has been described. However, the present invention is not limited to this, and the present invention may be applied to various cameras that handle image data electronically, such as a video camera.
In addition, the correction processing of the longitudinal chromatic aberration according to the present invention is not limited to three colors of R, G, and B, and correction processing may be performed for two or more colors (for example, four colors or six colors). Further, the axial chromatic aberration correction processing according to the present invention may be performed after correcting the lateral chromatic aberration of the imaging optical system 2 with a lens for correcting lateral chromatic aberration.

It is a block diagram which shows the structure of the digital still camera (aberration correction imaging device) which concerns on one Embodiment of this invention. It is a flowchart explaining operation | movement of the digital still camera which concerns on one Embodiment of this invention. It is a figure which shows the specific example of the reference | standard area | region set on the optical axis of an imaging optical system in the digital still camera which concerns on one Embodiment of this invention. It is a figure which shows schematically the operation | movement of the digital still camera which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state which image | photographs the image information in which only the center part is focused. It is a figure which shows the image information image | photographed in the state shown in FIG. It is a figure which shows schematically the operation | movement of the digital still camera which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state which image | photographs the image information in which only the center part is focused. It is a figure which shows the image information image | photographed in the state shown in FIG. It is a figure which shows the completion image information obtained by synthesize | combining the partial image information of the image information shown in FIG. 5, and the partial image information of the image information shown in FIG. It is a flowchart explaining the imaging | photography operation | movement in each reference | standard area | region of the digital still camera which concerns on one Embodiment of this invention. It is a figure explaining operation | movement of the digital still camera which concerns on one Embodiment of this invention. It is a figure which shows the example of the imaging | photography operation | movement in each reference | standard area | region of the digital still camera which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the mode at the time of acquisition of the image information of red light. It is a figure which shows the specific example of imaging | photography operation | movement in each reference | standard area | region of the digital still camera which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the mode at the time of the acquisition of the image information of green light. It is a figure which shows the specific example of imaging | photography operation | movement in each reference | standard area | region of the digital still camera concerning one Embodiment of this invention, Comprising: It is a figure which shows the mode at the time of the acquisition of the image information of blue light. It is a figure which shows the specific example of imaging | photography operation | movement of the digital still camera concerning one Embodiment of this invention, Comprising: (a) is a figure which shows the positional relationship of the reference area in an optical axis direction, (b) is each reference area. It is a figure which shows the position on the image sensor of the image obtained in (2).

Explanation of symbols

1 Digital still camera (aberration correction imaging device)
3 Imaging Optical System 5 Drive Device 20 System Controller (Control Device)
21 Image sensor
25 Data processing circuit (image processing device)

Claims (6)

An imaging optical system;
An image sensor for acquiring an image formed by the imaging optical system as image information;
A driving device that changes a relative distance between the imaging optical system and the imaging element in an optical axis direction of the imaging optical system;
While controlling the operation of the driving device to change the relative distance between the imaging optical system and the imaging element,
A control device that changes the relative distance and performs acquisition of image information by the imaging device a plurality of times;
A plurality of pieces of partial image information obtained by cutting out regions set in accordance with the relative distances are obtained from a plurality of pieces of image information acquired by the imaging element by changing the relative distance between the imaging optical system and the imaging element. And an image processing apparatus that obtains a plurality of pieces of image information for each predetermined wavelength of light and combines the partial image information and the image information for each predetermined wavelength to generate multicolor completed image information. apparatus.   2. The aberration correction according to claim 1, wherein the control device determines the relative distance between the imaging optical system and the imaging element and the number of acquisition times of the image information based on characteristics of image surface distortion of the imaging optical system. Imaging device. The control device controls the operation of the driving device to sequentially position the imaging element in a plurality of reference regions in the optical axis direction of the imaging optical system,
Controlling the operation of the image sensor to obtain image information in a state located in the reference region;
In acquiring the image information in the reference area, the operation of the driving device is controlled, and the relative distance between the imaging optical system and the imaging element is determined as the focal length for each predetermined wavelength of light of the imaging optical system. In order,
Image information is acquired by the imaging element in a state where the relative distance between the imaging optical system and the imaging element is set to each focal length for each predetermined wavelength of light of the imaging optical system. The aberration correction imaging apparatus according to claim 1 or 2.   The image processing apparatus is configured to generate the multi-color image information corresponding to the adjacent reference region using image information for each predetermined wavelength of the one or more common lights. 3. The aberration correction imaging apparatus according to 3. An aberration correction method in an imaging apparatus having an imaging optical system and an imaging element that acquires an image connected by the imaging optical system as image information,
Changing the relative distance between the imaging optical system and the imaging element in the optical axis direction of the imaging optical system;
Changing the relative distance between the imaging optical system and the image sensor, performing image information acquisition by the image sensor multiple times,
From a plurality of pieces of image information acquired by changing the relative distance between the image pickup optical system and the image pickup element, image information of a predetermined wavelength of light is respectively obtained for a plurality of reference regions in the optical axis direction of the image pickup optical system. To obtain multi-color image information corresponding to each of the reference regions by combining the image information of a predetermined wavelength of the light,
For each of the multicolor image information, partial image information obtained by cutting out an image area set in accordance with the relative distance of the reference area to which the multicolor image information corresponds is obtained, and the partial image information Aberration correction method for generating completed image information by combining.   The aberration correction method according to claim 5, wherein image information of a predetermined wavelength of the light corresponding to the adjacent reference region is generated using image information of a predetermined wavelength of the one or more common light.

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