JP4305142B2 - Image correction method and imaging apparatus - Google Patents

Description

  The present invention relates to an image correction method and an imaging apparatus for generating corrected image data by performing aberration correction conversion on image data acquired by an imaging unit based on the aberration characteristics of a lens.

  In an imaging unit (camera) in which a lens is assembled to a housing including an imaging element, the lens has aberration. Therefore, distortion due to lens aberration occurs in image data of a subject photographed through the lens. At that time, the lens aberration is generated in proportion to the square of the distance from the center position (optical axis) of the lens.

Therefore, as a method for correcting the lens aberration, there is a method of expressing the lens aberration characteristic by a mathematical expression and correcting the lens aberration based on the mathematical expression. An example of such a mathematical formula is shown below.
(Equation 1) Rd ² = Xd ² + Yd ²
(Expression 2) X = (Xd−Cx) {S1 × Rd ⁴ + S2 × Rd ² + S3} + Cx
(Equation 3) Y = (Yd−Cy) {S1 × Rd ⁴ + S2 × Rd ² + S3} + Cy
In Equations 1 to 3, Rd: distance from the center of the image sensor before correction to image coordinates, (Xd, Yd): image coordinates before correction, (X, Y): image coordinates after correction, (Cx , Cy): lens center coordinates, S1, S2, S3: coefficients (lens aberration characteristic values).

  Here, the reference plane of each coordinate is the imaging element plane. Therefore, for the sake of convenience, it is assumed that the center position of the lens (the optical axis of the camera) coincides with the center position of the image sensor, and the center position of the image sensor is defined as the center coordinate of the lens as the correction center position. The image data is subjected to aberration correction conversion based on .about.3.

  However, it is difficult to adjust the positional relationship between the lens and the image sensor so that the center position (optical axis) of the lens matches the center position of the image sensor. Actually, a positional deviation occurs between the center position of the lens and the center position of the image sensor due to an assembly error of the image sensor and / or lens. That is, distortion due to the shift occurs in the corrected image data.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image correction method and an imaging apparatus that can reduce distortion of corrected image data.

  In order to achieve the above object, the image correction method according to claim 1 corrects image data acquired by an image pickup unit in which a lens is assembled to a housing having an image pickup element based on aberration characteristics of the lens. This is an image correction method for generating corrected image data by performing aberration correction conversion by a correction unit. In that case, a part of the image sensor corresponding to the center position of the lens is detected, and aberration correction conversion is executed with the part as the center position in the correction.

  As described above, according to the image correction method of the present invention, the part of the imaging element surface corresponding to the center position (optical axis) of the lens is detected, and the aberration correction conversion is performed using the part as the center coordinate of the lens as the center position in the correction. Execute. Therefore, it is possible to reduce the distortion generated in the corrected image data, compared to the case where aberration correction conversion is performed using the center position of the image sensor as the center coordinate of the lens as in the prior art.

  Specifically, as described in claim 2, a position reference mark is provided on a test chart having a sufficient distance from the image pickup unit, and the optical axis of the image pickup unit passing through the center position of the lens is The imaging unit is positioned with respect to the position reference mark so as to be perpendicular to the plane of the chart and to substantially coincide with the position reference mark formation position in the test chart. Then, in the positioning state, an imaging chart including a position reference mark is imaged by the imaging unit, and image data is acquired to detect a part of the imaging element corresponding to the center position of the lens.

  As described above, according to the method of the present invention, the optical axis of the imaging unit passing through the center position of the lens is perpendicular to the plane of the test chart and substantially coincides with the position reference mark formation position in the test chart. As described above, the imaging unit is positioned with respect to the position reference mark. Accordingly, since the position reference mark coincides with the center position (optical axis) of the lens, the image data is obtained by capturing an image of the test chart including the position reference mark by the imaging unit and acquiring the image data in the positioning state. Therefore, the part of the image sensor corresponding to the center position of the lens can be detected with high accuracy.

  Since the imaging unit and the calibration chart having the position reference mark are at a sufficient distance, the optical axis of the imaging unit is positioned in the calibration chart by making the optical axis perpendicular to the calibration chart. The imaging unit can be easily positioned with respect to the position reference mark so as to substantially coincide with the formation position of the reference mark.

  Here, as a positioning method according to claim 2, for example, there is a method according to claim 3. According to this method, the laser beam emitting device is arranged on one of the test chart imaged by the imaging unit and the fixing device for positioning and fixing the imaging unit, and the mirror is arranged on the other. Then, the relative relationship between the laser light emitting device and the mirror is such that the laser light emitted from the laser light emitting device is perpendicular to the plane of the test chart and has the same optical path as the reflected light from the mirror of the laser light. Adjust the relative position. In this positioning state, replace with the position where the laser beam emitting device and mirror were placed, form a position reference mark on the calibration chart, and fix so that the optical axis of the imaging unit coincides with the optical axis of the laser beam An imaging unit is fixed to the apparatus. Thereby, the imaging device can be positioned with respect to the position reference mark.

  As described above, by using the laser beam emitting device and the mirror, the position reference mark formation position in the test chart and the fixing position of the imaging unit in the fixing device can be accurately determined.

  Then, the position reference mark is formed on the chart for inspection instead of the position where the laser beam emitting device and the mirror are arranged, and the image pickup unit is fixed to the fixing device, thereby easily picking up the image pickup device with respect to the position reference mark. Can be positioned.

  According to a fourth aspect of the present invention, it is preferable that the correction unit has a coordinate conversion map for correcting image distortion due to the aberration characteristics of the lens.

  The correction unit may have a mathematical expression based on the aberration characteristics of the lens. However, if the calculation result based on the mathematical expression is used as a coordinate conversion map, the correction processing time can be shortened.

  Next, as an image pickup apparatus that realizes the image correction method according to any one of claims 1 to 4, an image pickup unit in which a lens is assembled to a housing having an image pickup element and a center position of the lens as described in claim 5. A part of the corresponding image sensor is detected, a storage unit that stores the part as the center coordinate of the lens, and image data obtained by imaging the subject by the imaging unit, and aberration correction using the center coordinate of the lens as the correction center position And a correction unit for conversion.

  As described above, the imaging apparatus according to the present invention includes a storage unit that stores the part of the imaging element corresponding to the center position of the lens as the center coordinates of the lens. Then, the correction unit performs aberration correction conversion using the center coordinates of the lens as the correction center position. Therefore, the distortion generated in the corrected image data can be reduced as compared with the conventional case where aberration correction conversion is performed using the center position of the image sensor as the center coordinate of the lens.

  According to a sixth aspect of the present invention, the correction unit preferably has a coordinate conversion map for correcting image distortion due to the aberration characteristics of the lens.

  You may have a numerical formula based on the aberration characteristic of a lens as a correction | amendment part. However, the imaging apparatus of the present invention includes a storage unit that stores the part of the imaging element corresponding to the center position of the lens as the center coordinates of the lens. Accordingly, the correction processing time can be shortened by having the calculation result obtained by substituting the center coordinates of the lens into the mathematical formula based on the aberration characteristics of the lens as a coordinate conversion map.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of an imaging apparatus according to the present embodiment.

  As illustrated in FIG. 1, the imaging apparatus 100 includes a camera 10 as an imaging unit and an image processing unit 20 that processes image data obtained by imaging. Note that the imaging apparatus 100 according to the present embodiment further includes a monitor 30 as an output unit.

  The camera 10 includes a lens 11, an image sensor 12 using a CCD or CMOS, a circuit board 13 as a drive circuit, and a housing 14 that houses the lens 11, the image sensor 12, and the circuit board 13. Is. The camera 10 in the present embodiment is a CCD camera, and is disposed at a predetermined position of the vehicle so as to take an image including, for example, a vehicle side surface and a road travel division line (white line or the like). However, the imaging unit is not limited to the camera 10. For example, a camera that captures a still image such as a digital camera may be used.

  The image processing unit 20 includes a microcomputer as a main part, and stores an image memory that stores image data captured by the camera 10 and an image corresponding to the center position of the lens 11 from image data obtained by capturing a test chart described later. A detection unit that detects a part of the element 12, a storage unit that stores the detected center position of the lens 11 on the surface of the imaging element 12 as the center coordinate of the lens 11, and image data based on the center coordinate of the lens 11 A correction unit that performs correction conversion. Note that the image processing unit 20 may be integrated with either the camera 10 or the monitor 30.

  For example, the monitor 30 displays an image based on the corrected image data. A still image based on the image data may be displayed. In this case, the operator can check the monitor 30 to detect the part of the image sensor 12 corresponding to the center position of the lens 11. The output unit is not limited to the monitor 30 and may be a printer. Further, the detection result may be output as coordinates. Further, the imaging apparatus 100 does not necessarily have the monitor 30. For example, it is not necessary when the image processing unit 20 is configured to output a signal corresponding to the corrected image data only to the outside (for example, ECU).

  Here, the image data obtained by imaging the subject with the camera 10 has a shape that is distorted toward the periphery, for example, as shown in FIG. The aberration of the lens 11 is generated in proportion to the square of the distance from the center position (optical axis) of the lens 11.

As a method of correcting such distortion caused by the aberration of the lens 11, there is a method of correcting the aberration of the lens 11 based on a mathematical expression expressing the aberration characteristic of the lens 11. There are several such formulas, and one example is shown below.
(Equation 4) Rd ² = Xd ² + Yd ²
(Expression 5) X = (Xd−Cx) {S1 × Rd ⁴ + S2 × Rd ² + S3} + Cx
(Equation 6) Y = (Yd−Cy) {S1 × Rd ⁴ + S2 × Rd ² + S3} + Cy
In Equations 4 to 6, Rd: distance from the center of the image sensor 12 before correction to image coordinates, (Xd, Yd): image coordinates before correction, (X, Y): image coordinates after correction, (Cx , Cy): center coordinates of the lens 11, S1, S2, S3: coefficients (aberration characteristic values of the lens 11). The coefficients S1, S2, and S3 are provided in advance by the manufacturer of the lens 11, or obtained by imaging a lattice plate or the like in a state where the lens 11 and the image sensor 12 are in a normal positional relationship. Calculated based on the distortion rate of the image data.

  Cx and Cy shown in the above formulas 5 and 6 are the center coordinates of the lens 11, that is, the center position (optical axis) of the lens 11 on the surface of the imaging element 12. Conventionally, for the sake of convenience, it is assumed that the center position of the lens 11 coincides with the center position of the image sensor 12, and the center position of the image sensor 12 is defined as the center coordinates of the lens 11 that is the correction center position. The image data was subjected to aberration correction conversion based on Expression 6.

  However, it is difficult to attach the lens 11 and the image sensor 12 to the housing 14 with high accuracy so that the center position (optical axis) of the lens 11 and the center position of the image sensor 12 coincide. Actually, due to the assembly error of the lens 11 and / or the image sensor 12, as shown in FIG. 2B, the center position 11a of the lens 11 (broken line in FIG. 2B) and the center position 12a of the image sensor 12 ( A positional shift may occur in the alternate long and short dash line in FIG. In this case, even if the aberration correction processing is performed based on the equations 4 to 6 with the center of the image sensor 12 as the center coordinate of the lens 11, distortion due to the deviation occurs in the corrected image data.

  On the other hand, as described above, the imaging apparatus 100 according to the present embodiment, as the image processing unit 20, stores a storage unit that stores the detected center position of the lens 11 on the surface of the imaging element 12 as the center coordinates of the lens 11, and the lens. And a correction unit that performs aberration correction conversion on the image data based on the 11 center coordinates. Therefore, the distortion generated in the corrected image data can be reduced as compared with the conventional case.

  Next, an image correction method including a method for detecting the center coordinates of the lens 11 for manufacturing the above-described imaging apparatus 100 will be described. 3A and 3B are schematic diagrams for explaining the image correction method. FIG. 3A is a diagram for explaining a laser beam emitting device and a mirror as a position adjusting device, and FIG. 3B is a position reference mark and a camera. It is a figure for demonstrating the positional relationship with 10 optical axes 11a.

  First, the relative position between the center position 11a of the lens 11 (the optical axis of the camera 10) and the position reference mark is adjusted by the position adjusting device. In this embodiment, in order to adjust both positions, a laser beam emitting device and a mirror are used as a position adjusting device.

  As shown in FIG. 3A, a fixing device 50 for fixing the camera 10 is arranged with a sufficient interval with respect to the test chart 40. At this time, the positional relationship between the test chart 40 and the fixing device 50 is set to the same condition as when the test chart 40 is imaged by the camera 10 described later. In the present embodiment, the fixing device 50 is arranged so that the extending direction is parallel to the plane of the test chart 40 with a space of 3 m from the 3 m square test chart 40.

  Next, as a position adjusting device, the laser beam emitting device 60 is disposed on one of the test chart 40 and the fixing device 50, and the mirror 61 is disposed on the other. The laser light is emitted so that the laser light 60a emitted from the laser light emitting device 60 is perpendicular to the plane of the test chart 40 and has the same optical path as the reflected light 61a of the laser light 60a by the mirror 61. The relative positional relationship between the device 60 and the mirror 61 is adjusted. In the present embodiment, as shown in FIG. 3A, the mirror 61 is arranged on the test chart 40 and the laser light emitting device 60 is arranged on the fixing device 50 to adjust the positional relationship between them.

  After the positional relationship between the laser beam emitting device 60 and the mirror 61 is adjusted, the position reference is replaced with the position where the laser beam emitting device 60 and the mirror 61 are arranged, as shown in FIG. A mark 41 is formed, and the camera 10 is fixed to the fixing device 50 so that the optical axis (center position of the lens 11) 11a of the camera 10 coincides with the optical axis of the laser beam 60a. In the present embodiment, the optical axis 11a of the camera 10 is configured to coincide with the optical axis of the laser light 60a only by replacing the laser light emitting device 60 and the camera 10.

  In the present embodiment, as shown in FIG. 4, a black dot is formed as a position reference mark 41 at the imaging center of the calibration chart 40 by the camera 10 with respect to the white calibration chart 40. FIG. 4 is a plan view showing the imaging surface of the test chart 40. The position reference mark 41 is not particularly limited in color or shape as long as it has a color or brightness that is clearly different from other parts of the test chart 40. For example, a part corresponding to the position reference mark 41 of the test chart 40 may be cut out and light of a specific color may be emitted from the back side.

  As shown in the present embodiment, when the fixing device 50 is arranged at a sufficient interval that secures an imaging distance at which the captured image is not blurred with respect to the test chart 40, the camera 10 is fixed to the fixing device 50. When the camera 10 is attached to the test chart 40, the fixed position of the camera 10 with respect to the test chart 40 is slightly shifted in the vertical and horizontal directions (for example, when 3m is imaged in one horizontal line and 300 pixels / 1 line is used, As long as the mounting angle of the camera 10 with respect to the fixing device 50 (that is, the direction of the optical axis 11a of the camera 10) does not change even if the mounting position deviation is about 1 to 2 mm with respect to 10 mm per pixel, the position reference mark 41 and the camera Ten optical axes 11a can be made substantially coincident.

  As a result, the camera 10 is positioned with respect to the position reference mark 41 so that the optical axis 11a of the camera 10 substantially coincides with the formation position of the position reference mark 41 in the test chart 40. That is, the position of the position reference mark 41 in the captured image data indicates the position of the optical axis 11a of the camera 10 (the center position of the lens 11).

  As described above, by using the laser light emitting device 60 and the mirror 61 as the position adjusting device, the formation position of the position reference mark 41 in the verification chart 40 and the fixing position of the camera 10 in the fixing device 50 can be determined with high accuracy. Can do.

Further, since the position reference mark 41 and the camera 10 are arranged in place of the laser beam emitting device 60 and the mirror 61, the camera 10 can be easily positioned with respect to the position reference mark 41. Next, in this positioning state The test chart 40 including the position reference mark 41 is imaged by the camera 10, and the obtained image data is stored in an image memory (not shown) of the image processing unit 20. Then, the CPU of the image processing unit 20 serving as a detection unit detects a shift of the position reference mark 41 (the position of the position reference mark 41) with respect to the center position 12a of the image sensor 12 from the image data, and the center position of the image sensor 12 is detected. Based on the coordinates, the position of the position reference mark 41 is determined as the center coordinates of the lens 11. Then, the data of the center coordinates of the lens 11 is once input to the storage unit of the image processing unit 20. In the present embodiment, the angle of view of the camera 10 is 44 degrees.

  In the camera 10, if the center position 11a of the lens 11 and the center position 12a of the image sensor 12 are shifted, the position of the position reference mark 41 and the image sensor 12 in the obtained image data as shown in FIG. Center position 12a (intersection position of an alternate long and short dash line in FIG. 5) is shifted.

  In the present embodiment, the center coordinate of the lens 11 is determined from the shift amount of the position reference mark 41 with respect to the center position 12a with the center position 12a of the image sensor 12 as a reference. However, the position of the position reference mark 41 on the surface of the image sensor 12 may be directly obtained and used as the center coordinates of the lens 11.

  Even if the image processing unit 20 does not have a detection unit, the above-described image data is displayed on the monitor 30 as an image or coordinates, and the operator confirms the monitor 30 and a lens for the center position 12a of the image sensor 12. The center coordinates of the lens 11 can also be determined by detecting the shift of the center position 11a.

  Then, in the imaging device 100 in which the center coordinates of the lens 11 are stored, when the subject is imaged by the camera 10, the captured image data is stored in the image memory. The image processing unit 20 reads out the data of the center coordinate of the lens 11 from the storage unit, reads out the image data from the image memory, corrects the aberration of the image data with the center coordinate of the lens 11 as the correction center, and corrects the image. Generate data. The above is the image correction method shown in this embodiment.

  The image processing unit 20 has a coordinate conversion map as a correction unit. This coordinate conversion map is a map obtained by calculating the above-described mathematical expressions 4 to 6. The correction unit may calculate the image coordinates (xd, yd) after the correction process according to the above-described Expressions 4 to 6, but it takes time to calculate the coordinates after the correction process based on the respective expressions. Therefore, it is preferable to have a coordinate conversion map.

  Further, the image processing unit 20 outputs an image based on the corrected image data to the monitor 30 as necessary, and outputs a signal corresponding to the corrected image data to the outside (for example, ECU).

  Further, the center coordinates of the lens 11 are not input to the storage unit (for example, when the center coordinates of the lens 11 are determined by the operator as described above), and are substituted in advance into the expressions 5 and 6 together with the coefficients S1, S2, and S3. If the correction unit has the coordinate conversion map, the image processing unit 20 reads only the captured image data from the image memory, and the correction unit performs aberration correction conversion.

  Here, the effect of the image correction method shown in the present embodiment will be described with reference to FIGS.

  For comparison, the image area of the corrected image data (vertical 488 pixels and horizontal 648 pixels in the present embodiment) is equally divided into four as shown in FIG. Sites of lattice points (X0, Y0) to (X5, Y5) divided into 6 parts in the y direction were used as measurement points. Note that (X0, Y0) is the center position 12a of the image sensor 12. In FIGS. 6B and 6C and FIGS. 7A and 7B, the error is an aberration correction conversion in a state where the center position 11a of the lens 11 coincides with the center position 12a of the image sensor 12. This shows the deviation of each measurement point with respect to the corrected image data (ideal value) when.

  6B and 6C show aberration correction conversion with the center position 12a of the image sensor 12 and the center position 11a of the lens 11 shifted by 10 pixels, with the center position 12a of the image sensor 12 as the center coordinates of the lens 11. FIG. FIG. 6B is a diagram showing an error in each x-axis direction and FIG. 6C is a diagram showing an error in the y-axis direction.

  7A and 7B detect a shift (10 pixels as in FIG. 6) of the center position 11a of the lens 11 with respect to the center position 12a of the image sensor 12, and the lens 11 is positioned on the surface of the image sensor 12. 11A and 11B are diagrams illustrating the error of each measurement point with respect to the ideal value of the corrected image data subjected to the aberration correction conversion, as a center coordinate of FIG. 11, FIG. 7A is an error in the x-axis direction, and FIG. It is a figure which shows an error.

  As shown in FIGS. 6B and 6C, when the aberration correction conversion is performed using the center position 12a of the image sensor 12 as the center coordinates of the lens 11 without detecting the center position 11a of the lens 11, Distortion and error occur based on the deviation between the center position 12a and the center position 11a of the lens 11. In particular, the error is large because the periphery of the image area (that is, the periphery of the imaging area) is far from the center coordinates of the lens 11 (in this case, the center position 12a of the image sensor 12 is used as a substitute).

  On the other hand, as shown in FIGS. 7A and 7B, when the center position 11a of the lens 11 is detected and aberration correction conversion is performed using the center position 11a as the center coordinates of the lens 11, FIGS. The error was reduced compared to the case shown in (c). In particular, the error in the periphery of the image area (that is, the periphery of the imaging area) was the same as that in the center direction of the image sensor 12.

  As described above, according to the image correction method of the present embodiment, the center position (optical axis 11a) of the lens 11 on the surface of the image sensor 12 can be detected with high accuracy, and the center position 11a of the lens 11 is determined as the center coordinates of the lens 11. As described above, the aberration correction processing can be executed based on the above-described mathematical expressions 4 to 6. Therefore, the obtained corrected image data is less distorted than before.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In this embodiment, the example which uses the laser beam emission apparatus 60 and the mirror 61 as a position adjustment apparatus which performs relative position adjustment of the position reference mark 41 and the optical axis 11a of the camera 10 was shown. However, other than that, a straight line connecting the formation position of the position reference mark 41 in the test chart 40 and the fixed position of the camera 10 in the fixing device 50 is in the plane of the test chart 40 and the extending direction of the fixing device 50. A position where the position reference mark 41 is formed and the fixing position of the camera 10 (the angle of the optical axis 11a of the camera 10) can be determined (for example, a thread is attached to the test chart 40 and the fixing device 50). Can be applied if present.

1 is a diagram illustrating a schematic configuration of an imaging apparatus according to a first embodiment of the present invention. (A) is a figure for demonstrating distortion by lens aberration, (b) is a figure for demonstrating the shift | offset | difference of the center position of a lens, and the center position of an image pick-up element. It is the schematic for demonstrating the image correction method, (a) is a schematic diagram for demonstrating the laser beam emission apparatus and mirror as a position adjustment apparatus, (b) is a position reference mark and the optical axis of a camera. It is a schematic diagram for demonstrating positional relationship. It is a figure for demonstrating the chart for a test | inspection. It is a schematic diagram for demonstrating the shift | offset | difference of the position reference mark and image pick-up element center in the imaged image data. In the state where the center position of the image sensor and the center position of the lens are shifted, the center position of the image sensor is the center coordinate of the lens, and shows the error of each measurement point with respect to the ideal value of the corrected image data subjected to aberration correction conversion. (A) is a figure for demonstrating a measurement point, (b) is a figure which shows the error of a x-axis direction, (c) is a figure which shows the error of a y-axis direction. The figure which shows the difference | error of each measurement point with respect to the ideal value of the correction | amendment image data which carried out the aberration correction conversion by detecting the shift | offset | difference of the center position of the lens with respect to the center position of an image pick-up element, and using the center position of a lens as the center coordinate of a lens (A) is a diagram showing an error in the x-axis direction, and (b) is a diagram showing an error in the y-axis direction.

Explanation of symbols

10 ... Camera 11 ... Lens 11a ... Optical axis (center position of lens 11)
DESCRIPTION OF SYMBOLS 12 ... Image pick-up element 12a ... Center position 20 of image pick-up element ... Image processing unit 40 ... Test chart 41 ... Position reference mark 60 ... Laser beam emission apparatus 61 ... Mirror 100 ... Imaging devices

Claims (6)

An image correction method for generating corrected image data by performing aberration correction conversion on image data acquired by an image pickup unit in which a lens is assembled to a housing having an image pickup element, and correcting the image data based on the aberration characteristics of the lens Because
An image correction method comprising: detecting a part of the imaging element corresponding to a center position of the lens, and executing the aberration correction conversion with the part as a center position in correction. A position reference mark is provided on the calibration chart having a sufficient interval between the imaging section, and the optical axis of the imaging section passing through the center position of the lens is perpendicular to the plane of the calibration chart, And positioning the imaging unit with respect to the position reference mark so as to substantially coincide with the formation position of the position reference mark in the test chart,
In the positioning state, the imaging chart including the position reference mark is imaged by the imaging unit, and image data is acquired to detect a part of the imaging element corresponding to the center position of the lens. The image correction method according to claim 1. A laser light emitting device is disposed on one of the test chart imaged by the imaging unit and a fixing device for positioning and fixing the imaging unit, and a mirror is disposed on the other.
The laser light emitting device and the mirror so that the laser light emitted from the laser light emitting device is perpendicular to the plane of the test chart and has the same optical path as the reflected light of the laser light by the mirror. With the relative positional relationship between and adjusted,
In place of the laser beam emitting device and the mirror, the position reference mark is formed on the verification chart, and the imaging unit is connected to the fixing device so that the optical axis of the imaging unit coincides with the optical axis of the laser beam. The image correction method according to claim 2, wherein the imaging unit is positioned with respect to the position reference mark by fixing the position reference mark.   The image correction method according to claim 1, wherein the correction unit includes a coordinate conversion map for correcting image distortion due to the aberration characteristic of the lens. An imaging unit formed by assembling a lens in a housing including an imaging element;
A storage unit that detects a part of the imaging element corresponding to a center position of the lens and stores the part as a center coordinate of the lens;
An image pickup apparatus comprising: a correction unit configured to perform aberration correction conversion on image data obtained by picking up an image of a subject with the image pickup unit using a center coordinate of the lens as a correction center position.   The imaging apparatus according to claim 5, wherein the correction unit includes a coordinate conversion map for correcting image distortion due to the aberration characteristic of the lens.

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