JP2004241823A - Imaging method and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the need of the process of readjusting an optical system to cope with the peripheral focus deviation, etc., without adopting high-precision components or high-precision manufacturing processes. <P>SOLUTION: The apparatus comprises a focus control means for obtaining focusing information for focusing an object image, an imaging optical system driving means for adjusting the focus based on the focusing information, an imaging means for taking the object image formed by an imaging optical system, a memory means for storing relative focus position information representing the focus deviation quantity in a non-focus area, a control means for controlling the imaging operation in a focused state onto the non-focus area and the imaging operation in a focused state onto a focus area, and an image composing means for composing image data obtained in the focused state onto the non-focus area with image data obtained in the focused state onto the focus area. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an imaging method and an imaging apparatus for imaging using an imaging element such as a CCD, and more particularly to an improvement in an imaging method and an imaging apparatus capable of obtaining a good imaging result.
[0002]
[Prior art]
In the case of a general digital camera, focusing information is obtained for a predetermined focus area (such as the center of an imaging range), and at least a part of the imaging optical system is driven based on the focusing information to adjust the focus. The imaging optical system is configured to capture a subject image formed by the imaging optical system.
[0003]
By the way, in digital cameras and digital video cameras of this type, the lens system tends to be downsized with the downsizing of solid-state imaging devices such as CCDs. Further, since the number of pixels of the CCD tends to increase, higher accuracy is required.
[0004]
In a lens system that requires such high precision, despite being focused at the center of the imaging range and achieving high resolution, it is difficult to focus on a part of the periphery due to problems such as optical axis deviation of the lens. In some cases, an out-of-focus state (one-sided blur) or an out-of-focus state in the entire periphery (peripheral blur) may occur. In this specification, the above-described one-sided blur and peripheral blur are collectively described as peripheral blur.
[0005]
Such a phenomenon has become a serious problem in the case of a digital camera which is required to have high accuracy in accordance with miniaturization.
[0006]
If it is found at the stage of manufacturing inspection that such peripheral blurring has occurred, a method such as shipping after re-adjustment may be taken as described in Patent Document 1 described below. there were.
[0007]
[Patent Document 1]
JP-A-11-202204 (page 1, FIG. 1)
[0008]
[Problems to be solved by the invention]
As described above, if readjustment is performed before shipment, there is a problem in that the number of steps before shipment increases and the manufacturing cost increases. It is also possible to incorporate high-precision parts and manufacturing steps in advance so that a readjustment step is not necessary. However, in that case, there is a problem in that parts costs and manufacturing costs increase.
[0009]
The present invention has been made in view of the above problems, and eliminates the need for a process of re-adjustment of an optical system without incorporating high-precision parts or a high-precision manufacturing process for measures against peripheral blur, etc. It is an object of the present invention to realize a photographing method and an image pickup apparatus capable of performing such operations.
[0010]
[Means for Solving the Problems]
That is, the present invention for solving the above-mentioned problems is as described below.
[0011]
(1) According to the first aspect of the present invention, focusing information is obtained for a predetermined focus area, and focus adjustment is performed by driving at least a part of the imaging optical system based on the focusing information. An imaging method for imaging a subject image formed according to (1), wherein relative focus position information indicating a focus shift amount with respect to the focus area in a predetermined non-focus area other than the focus area is stored in advance. Performing imaging in a state where the focus area is focused, and imaging in a state where the non-focus area where the relative focus position information exists based on the relative focus position information The image data obtained in a state where the focus area is focused on the non-focus area obtained in a state where the relative focus position information is present in the non-focus area. Synthesizing the image data of an imaging method, characterized in that.
[0012]
Also, the invention according to claim 2 is an imaging optical system for forming an image of a subject, a focus control unit for obtaining focusing information for focusing the subject image on a predetermined focus area, and An imaging optical system driving unit that performs focus adjustment by driving at least a part of the imaging optical system based on focus information; an imaging unit that captures a subject image formed by the imaging optical system; and the focus area. A focus position information storage unit that stores relative focus position information indicating a focus shift amount with respect to the focus area in a predetermined non-focus area other than the above, and imaging in a state where the focus area is focused; Based on the relative in-focus position information stored in the in-focus position information storage means, imaging in a state where the in-focus area in which the relative in-focus position information exists is focused. Control means for controlling to perform the operation, and the non-focus obtained in a state where the image data obtained in a state where the focus area is focused is focused on a non-focus area where the relative focus position information exists. An image capturing apparatus comprising: image combining means for combining image data of an area.
[0013]
The invention according to claim 3 is the imaging apparatus according to claim 2, wherein the non-focus area is defined in a peripheral portion included in an imaging range.
[0014]
The invention according to claim 4 is the imaging apparatus according to claim 2, wherein the non-focus area is set at a plurality of positions in a peripheral portion included in an imaging range.
[0015]
According to these inventions, focus information is obtained for a predetermined focus area (such as a center portion of an imaging range), and at least a part of an imaging optical system is driven based on the focus information to perform focus adjustment. When capturing a subject image formed by the optical system, relative focus position information indicating a focus shift amount with respect to the focus area in a predetermined non-focus area other than the focus area is stored in advance, and the focus is adjusted. Focusing is performed on an image in a state where the area is in focus, and on the basis of the relative focus position information, an image is focused on a non-focus area where the relative focus position information exists. For the image data obtained in a state where the area is in focus, the non-focus obtained in a state where the non-focus area where the relative focus position information exists is obtained To synthesize the image data of the rear.
[0016]
By doing so, it is possible not only to focus on a predetermined focus area, but also to generate image data in a focused state in a non-focus area at a peripheral position of the imaging range. Therefore, it is possible to eliminate the need for a readjustment step of the optical system without introducing a high-precision component or a high-precision manufacturing process. Further, it is possible to obtain an image having a high resolution without a sense of incongruity due to peripheral blur or the like in the peripheral portion.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of main electric parts when an imaging method and an imaging apparatus according to an embodiment of the present invention are applied to a digital camera 100. FIG. 3 is an explanatory diagram showing an external configuration of the digital camera 100.
[0018]
First, the digital camera 100 will be briefly described with reference to FIG. In front of the digital camera 100, there are provided an image pickup unit 102 for picking up an image of a subject, an auxiliary light emitting unit 122 for irradiating auxiliary light to an object to be shot, and a finder 125 for determining a shooting range. Also, on the back, an image display unit 108 for displaying a captured image and the like, a display unit 126 for displaying a shooting setting status and the like, an operation switch 121 for setting and switching various functions, and Is provided. A release switch 121a for operating the release is provided on the upper surface.
[0019]
In FIG. 1, reference numeral 101 denotes a CPU as control means for controlling each unit of the digital camera 100. The CPU 101 executes an imaging process based on an application program stored in an EEPROM described later.
[0020]
An imaging unit 102 includes a lens unit 102a, an aperture 102b, and a CCD 102c and captures a subject image. Note that the lens unit 102a and the stop 102b constitute an imaging optical system.
[0021]
An imaging circuit 104 performs various processes on a read signal from the CCD 102c to generate an image signal. Note that the CCD 102c and the imaging circuit 104 constitute an imaging unit. Reference numeral 105 denotes an AD conversion circuit, which converts an analog image signal into a digital image signal. The A / D conversion circuit 105 outputs a digital image signal to the memory 106 and the AE / AF processing circuit 113.
[0022]
Reference numeral 106 denotes a work memory for temporarily storing image signals, which stores image signals immediately before image display and image recording, and performs image synthesis processing which is a characteristic operation of the present embodiment. Do. For this image synthesis, it is necessary to have at least a capacity capable of storing image signals for a plurality of screens. Note that the CPU 101 and the memory 106 constitute an image synthesizing unit.
[0023]
Reference numeral 107 denotes a DA conversion circuit that DA converts an image signal stored in the memory 106 into an analog image signal for image display. Reference numeral 108 denotes an image display unit configured with a liquid crystal display panel or the like, and displays an image signal from the DA conversion circuit 107. The display is not limited to the image to be captured, but may be a text screen for various settings.
[0024]
Reference numeral 109 denotes a recording memory for recording a captured image, and corresponds to various types of memory cards that can be used in the digital camera 100. The recording memory 109 may be of a type that can be inserted into and removed from the digital camera 100, or may be of a type that is built into the digital camera 100.
[0025]
A compression / expansion circuit 110 performs a compression process for generating a compressed image signal to be recorded in the memory 109 and a decompression process for reading the compressed image signal from the memory 109 and returning it to an image signal.
[0026]
A timing generator (TG) 112 generates a predetermined timing signal for imaging. The timing signal generated by the TG 112 is supplied to the CPU 101, the imaging circuit 104, the CCD driver 114, and the like.
[0027]
An AE / AF processing circuit 113 executes an AE (Auto Exposure: automatic exposure control) process for obtaining an appropriate exposure condition and an AF (Auto Focus: automatic focus control) process for focusing, and calculates a calculation result. Is transmitted to the CPU 101. The CPU 101 controls the aperture 102b based on the calculation result of the AE, and controls the lens unit 102a based on the calculation result of the AF.
[0028]
The AE / AF processing circuit 113 obtains focusing information for focusing a subject image on a predetermined focus area (a central portion of the screen, etc.), and constitutes a focus control unit. .
[0029]
In this embodiment, a passive AF method is used as the focus control means, but the focus control means is not limited to this. That is, it is also possible to use an active AF method that irradiates an object with infrared rays, ultrasonic waves, or the like.
[0030]
Reference numeral 114 denotes a CCD driver that drives the CCD 102c using a timing signal from the TG 12, and controls the charge accumulation time based on an instruction from the CPU 101.
[0031]
Reference numeral 115 denotes a first motor (first M) for controlling the exposure of the aperture 102b, and reference numeral 116 denotes a first motor drive circuit for driving the first M 115. The CPU 101 controls the first motor drive circuit 116 based on the AE calculation result from the AE / AF processing circuit 113.
[0032]
Reference numeral 117 denotes a second motor (2M) for controlling focusing of the lens unit 102a, and 118 denotes a second motor drive circuit for driving the second M117. The CPU 101 controls the second motor drive circuit 118 based on the AF calculation result from the AE / AF processing circuit 113.
[0033]
Reference numeral 119 denotes a battery that supplies necessary power to each section of the digital camera 100, and supplies a stable voltage power to each section via a stabilizing circuit or a booster circuit (not shown) as necessary.
[0034]
Reference numeral 120 denotes an EEPROM in which an application program for the CPU 101 to control each unit of the digital camera 100 is stored. In this embodiment, relative focus position information indicating a focus shift amount with respect to the focus area in a predetermined non-focus area other than the focus area is stored in the EEPROM 120 in advance.
[0035]
Reference numeral 121 denotes an operation switch provided with various switches, and is a general term for a release switch 121a, a mode switch 121b, and other various switches. The operation result of the operation SW 121 is transmitted to the CPU 101. The release SW 121a is configured to be able to be pressed in two stages. The first stage is a release S1 for AE / AF processing, and the second stage is a release S2 for actual photographing. .
[0036]
Reference numeral 122 denotes an auxiliary light emitting unit that irradiates the subject with auxiliary light (auxiliary light or strobe light) when the luminance is insufficient at the time of shooting, and the light emission timing and light emission amount are controlled by the switching circuit 123.
[0037]
Note that the relative focus position information is stored in advance in the EEPROM 120 of the digital camera 100 according to the present embodiment, as described above.
[0038]
Here, as the relative focus position information, at the time of inspection before shipment of the digital camera 100, inspection such as blurring around the lens unit 102a is performed, and the focus area (usually, the central portion of the shooting range) is focused. Then, relative focus position information indicating a focus shift amount (relative focus position) with respect to the focus area in a predetermined non-focus area other than the focus area is obtained.
[0039]
Here, in the example shown in FIG. 4A, the predetermined non-focus area means four places (circled in the figure) of diagonally upper left, diagonally upper right, diagonally lower left, and diagonally lower right. In addition, it is possible to divide into a total of five areas around the non-focus area and the focus area portion. In the example shown in FIG. 4B, the predetermined non-focus areas mean four places (upper, right, left, and lower) (circles in the figure). In addition, it is possible to divide into a total of five areas around the non-focus area and the focus area portion. Further, in the example shown in FIG. 4 (c), the predetermined non-focus areas include eight locations (circled in the figure) of upper, right, left, lower, diagonally upper left, diagonally upper right, diagonally lower left, and diagonally lower right. means. In addition, it is possible to divide the non-focus area and the focus area portion into nine areas in total. Note that these are just examples, and the present invention is not limited to the examples shown here.
[0040]
It should be noted that the relative focus position information on the above non-focus area is obtained at different distances to the subject, for example, 1 m, 3 m, 10 m,. In the case where a zoom lens is used, the distance to the subject is changed in the same manner for each of the focal lengths such as the wide-angle side, the standard side, and the telephoto side, and the relative focus position information on the above non-focus area is obtained. Get it.
[0041]
When the relative focus position information is obtained in this way, the focus shift with respect to the focus area exceeding the inspection pass criterion and one-sided blurring is generated and stored in the EEPROM 120 as the relative focus position information. deep. In this case, the position in the imaging range, the distance to the subject, the focal length, and the focus shift amount are stored as a series of data. It is not necessary to accumulate in the EEPROM 120 if the defocus is below the inspection pass criterion.
[0042]
Hereinafter, an operation of the digital camera 100 according to the present embodiment will be described with reference to a flowchart of FIG.
[0043]
In the digital camera 100 according to this embodiment, the AE / AF processing circuit 113 obtains focusing information for a predetermined focus area (the center of the imaging range, etc.), and controls the CPU 101 based on the focusing information. By driving at least a part of the lens unit 102a, focus adjustment is performed, thereby capturing a subject image formed on the CCD 102c.
[0044]
Here, at the time of photographing, the CPU 101 monitors the pressed state of the release SW 121a (Step 1 in FIG. 2), and confirms that the first stage (release S1) of the release SW 121a is pressed (Y in Step 1 in FIG. 2). ), And causes the AE / AF processing circuit 113 to perform distance measurement and photometry (step 2 in FIG. 2).
[0045]
The CPU 101 monitors the pressed state of the release SW 121a (step 3 in FIG. 2), and the distance measurement and the photometry continue until the second stage of the release SW 121a is pressed.
[0046]
When it is confirmed that the second step (release S2) of the release SW 121a is pressed (Y in Step 3 in FIG. 2), the CPU 101 drives the lens unit 102a based on the AF calculation result (Step 4 in FIG. 2). Then, a read signal read from the CCD 102c by performing imaging is converted into an image signal and stored in the memory 106 (Step 5 in FIG. 2). Note that the AF driving and the imaging at this time are for the central portion of the imaging range in FIG. 4 and the peripheral portion where there is no relative focus position information.
[0047]
Here, the CPU 101 refers to the relative in-focus position information on the EEPROM 120, and if there is no relative in-focus position information (N in step 6 in FIG. 2), the image signal stored in the memory 106 is compressed and expanded by the compression / expansion circuit. After being converted into a compressed image signal by 110, it is recorded in a recording memory (step 10 in FIG. 2).
[0048]
Here, if the relative in-focus position information exists on the EEPROM 120 (Y in step 6 in FIG. 2), it means that the peripheral blur has been found at the time of the inspection, and the focus shift is eliminated in the peripheral blur portion. Then, the lens unit 102a is driven in consideration of the relative focus position information with respect to the AF calculation result at the center of the screen (Step 7 in FIG. 2).
[0049]
If the actual distance to the subject does not completely match the stored relative focus position information, the distance may be obtained by interpolation using a plurality of pieces of relative focus position information.
[0050]
Similarly, if the zoom position does not accumulate relative focus position information at all focal lengths, the zoom position may be obtained by interpolation using a plurality of relative focus position information.
[0051]
When the driving of the lens unit 102a based on the relative focus position information is completed, the read signal read from the CCD 102c is converted into an image signal and stored in the memory 106 (Step 8 in FIG. 2). Note that the focus drive and the imaging at this time are for a peripheral portion where relative focus position information exists (peripheral blur occurs) in FIG.
[0052]
If there is not one but a plurality of peripheral portions where relative focus position information is present (peripheral blur is present), the CPU 101 controls the focus driving and imaging in steps 6 to 8. Are repeatedly executed, and the obtained image signals are stored in the memory 106.
[0053]
In addition, it is preferable that the above-described focus driving and imaging be performed almost continuously in as short a time as possible so as not to cause a sense of incongruity when combining images.
[0054]
Then, the CPU 101 performs image synthesis on the memory 106 for the plurality of image signals obtained as described above. That is, the image data of the non-focus area obtained in a state of focusing on the non-focus area where the relative focus position information exists is synthesized with the image data of the state of focusing on the focus area. .
[0055]
FIG. 5 shows a case where the non-focus area where the relative focus position information exists is only the upper right part when the areas are divided as shown in FIG. 4A. In this case, image data (see FIG. 5A) in a state excluding a non-focus area where the relative focus position information exists is generated from image data obtained in a state where the focus area is focused, On the other hand, the image data (see FIG. 5B) of the non-focus area obtained in a state where the focus is on the non-focus area in which the relative focus position information exists is synthesized to form the entire image data. (See FIG. 5C).
[0056]
It is also desirable to perform image processing such as smoothing and averaging in a certain range near the boundary so as to prevent inconsistency in images of the subject and the like at the boundary where image synthesis is performed.
[0057]
Then, the image data generated by performing the image synthesis as described above is converted into a compressed image signal by the compression / expansion circuit 110, and then recorded in the recording memory 109 (Step 10 in FIG. 2).
[0058]
By performing the imaging and the image synthesis as described above, it is possible to generate image data in a state where not only the focus is performed in the predetermined focus area but also the non-focus area in the peripheral position of the imaging range. Therefore, it is possible to eliminate the need for a step of re-adjusting the optical system without introducing a high-precision component or a high-precision manufacturing process to take measures against peripheral blurring or the like.
[0059]
Further, since the readjustment step is not required, a high-performance digital camera can be manufactured at low cost. Further, it is possible to obtain an image having a high resolution without a sense of incongruity due to peripheral blur or the like in the peripheral portion.
[0060]
<Other Embodiments (1)>
In the above description, the predetermined focus area is set as the central portion of the imaging range. However, the present embodiment is also applied to a case where the focus area can be selected by the user and a case where the focus area can be arbitrarily moved. It is possible to apply.
[0061]
<Other Embodiments (2)>
Further, regarding the order of imaging, it is not necessary that the predetermined focus area (the center part of the imaging range in the above specific example) is first, and before the start of imaging, the focus lens can be driven continuously in one direction. The imaging order may be changed with reference to the focus position and the out-of-focus direction of the non-focus area.
[0062]
<Other Embodiments (3)>
As the focus control, in the above-described embodiment, a passive AF method that obtains focusing information by driving an imaging lens is used, but the focus control is not limited to this. That is, it is also possible to use an active AF method that irradiates an object with infrared rays, ultrasonic waves, or the like.
[0063]
【The invention's effect】
As described above, in the present invention, focusing information is obtained for a predetermined focus area (such as the center of an imaging range), and at least a part of the imaging optical system is driven based on the focusing information. When performing focus adjustment and capturing a subject image formed by the imaging optical system, relative focus position information indicating a focus shift amount with respect to the focus area in a predetermined non-focus area other than the focus area is previously determined. The image is stored in a state where it is focused on the focus area, and based on the relative focus position information, the image is focused on a non-focus area where the relative focus position information exists. With respect to image data obtained in a state in which focus is performed in a focus area, imaging is performed in a state in which focus is obtained in a non-focus area in which the relative focus position information exists. Synthesizing the image data of the non-focus area. By doing so, it is possible not only to focus on a predetermined focus area, but also to generate image data in a focused state in a non-focus area at a peripheral position of the imaging range. Therefore, it is possible to eliminate the need for a re-adjustment step without introducing a high-precision part or a high-precision manufacturing process.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an electrical configuration of a digital camera to which an embodiment of an imaging method and an imaging apparatus according to an embodiment of the present invention is applied.
FIG. 2 is a flowchart illustrating an operation state of imaging according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating an external configuration of a digital camera according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a focus area and a non-focus area in imaging according to the embodiment of the present invention.
FIG. 5 is an explanatory diagram illustrating a state of image synthesis in imaging according to the embodiment of the present invention, using a specific example.
[Explanation of symbols]
100 Digital camera 101 CPU
102 imaging unit 104 imaging circuit 105 A / D conversion circuit 106 memory 107 D / A conversion circuit 108 image display unit 109 recording memory 110 compression / expansion circuit 113 AE / AF processing circuit 120 EEPROM
121 Operation SW

Claims (4)

Imaging that obtains focusing information for a predetermined focus area, adjusts focus by driving at least a part of an imaging optical system based on the focusing information, and captures a subject image formed by the imaging optical system. The method,
In a predetermined non-focus area other than the focus area, relative focus position information indicating a focus shift amount with respect to the focus area is stored in advance, and imaging in a state where the focus area is focused is performed. Based on the target in-focus position information, perform imaging in a state where the non-focus area where the relative in-focus position information is present is focused,
For the image data obtained in a state where the focus area is focused, the image data of the non-focus area obtained in a state where the relative focus position information is present in the non-focus area is synthesized,
An imaging method characterized in that: An imaging optical system for forming a subject image,
Focus control means for obtaining focus information for focusing the subject image on a predetermined focus area;
Imaging optical system driving means for performing focus adjustment by driving at least a part of the imaging optical system based on the focusing information;
Imaging means for imaging a subject image formed by the imaging optical system;
A focus position information storage unit that stores relative focus position information indicating a focus shift amount with respect to the focus area in a predetermined non-focus area other than the focus area;
Focusing on a non-focus area where the relative focus position information exists based on the imaging in a state where the focus area is focused and the relative focus position information stored in the focus position information storage means Control means for controlling to perform imaging in a state in which the
Image synthesis for synthesizing image data obtained in a state where the focus area has been focused on image data obtained in a state where the relative focus position information exists, with image data obtained in a state where the focus area is focused on the non-focus area Means,
An imaging device comprising: The non-focus area is defined in a peripheral portion included in the imaging range,
The imaging device according to claim 2, wherein: The non-focus area is defined at a plurality of positions of a peripheral portion included in the imaging range,
The imaging device according to claim 2, wherein:

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