Method, apparatus, and computer program for correcting optical axis of zoom lens
A method of correcting an optical axis of a zoom lens includes obtaining a degree of optical axis misalignment corresponding to a current zoom lens state of a camera, considering the current zoom lens state of the camera and data previously stored to define a relationship between a state of the zoom lens of the camera and the degree of optical axis misalignment, determining digital zoom information to compensate for the degree of optical axis misalignment, considering the degree of optical axis misalignment, and generating correction image data by cropping and magnifying image data photographed by the camera to correspond to the digital zoom information.
1. A method of correcting an optical axis of a zoom lens, the method comprising:
obtaining a degree of optical axis misalignment corresponding to a current zoom lens state of a camera, considering the current zoom lens state of the camera and data previously stored to define a relationship between a state of the zoom lens of the camera and the degree of optical axis misalignment;
determining digital zoom information to compensate for the degree of optical axis misalignment, considering the degree of optical axis misalignment; and
generating correction image data by cropping and magnifying image data photographed by the camera to correspond to the digital zoom information.
2. The method of claim 1 , wherein the obtaining of the degree of optical axis misalignment comprises obtaining the degree of optical axis misalignment corresponding to the current zoom lens state by referring to the previously stored data,
the digital zoom information comprises a digital zoom magnification ratio and crop information,
the determining of the digital zoom information comprises determining the digital zoom magnification ratio and the crop information, considering the degree of optical axis misalignment, and
the generating of the correction image data comprises generating the correction image data by zooming the image data by the digital zoom magnification ratio and cropping the image data to correspond to the crop information.
3. The method of claim 1 , wherein the previously stored data comprises a look-up table including a plurality of indexes including a zoom lens state and a degree of optical axis misalignment matching the zoom lens state, and
the determining of the digital zoom information comprises determining the digital zoom information on the basis of the degree of optical axis misalignment included in an index corresponding to the current zoom lens state of the indexes included in the look-up table.
4. The method of claim 3 , wherein the determining of the digital zoom information comprises, when the look-up table does not include an index corresponding to the current zoom lens state, obtaining the degree of optical axis misalignment corresponding to the current zoom lens state on the basis of interpolation of data included in the indexes included in the look-up table.
5. The method of claim 1 , wherein the determining of the digital zoom information comprises determining the digital zoom information further considering a resolution of a frame of the image data.
6. The method of claim 5 , wherein the resolution comprises a first axis component and a second axis component that is different from the first axis component,
the degree of optical axis misalignment comprises the first axis component and the second axis component, and
the determining of the digital zoom information comprises determining the digital zoom information, considering the first axis component and the second axis component of the degree of optical axis misalignment and the first axis component and the second axis component of the resolution.
7. The method of claim 6 , wherein the determining of the digital zoom information comprises determining the digital zoom information on the basis of a greater value between the degree of optical axis misalignment relative to the resolution with respect to the first axis and the degree of optical axis misalignment relative to the resolution with respect to the second axis.
8. The method of claim 7 , wherein the digital zoom information comprises a digital zoom magnification ratio and crop information, and
the determining of the digital zoom information comprises determining the digital zoom magnification ratio on the basis of the greater value and the crop information on the basis of the digital zoom magnification ratio and the degree of optical axis misalignment.
9. The method of claim 7 , wherein the determining of the digital zoom information comprises determining the digital zoom information on the basis of a value calculated by using an Equation below,
Max
(
R
1
R
1
-
P
1
×
2
,
R
2
R
2
-
P
2
×
2
)
wherein “R 1 ” denotes a resolution of the first axis component, “P 1 ” denotes the degree of optical axis misalignment of the first axis component, “R 2 ” denotes a resolution of the second axis component, and “P 2 ” denotes the degree of optical axis misalignment of the second axis component.
10. The method of claim 1 , wherein the digital zoom information comprises a digital zoom magnification ratio and crop information,
the generating of the correction image data comprises generating the correction image data by cropping the image data according to the crop information and magnifying cropped image data by the digital zoom magnification ratio, and
a frame size of the correction image data is the same as a frame size of the image data.
11. The method of claim 1 , wherein the obtaining of the degree of optical axis misalignment comprises further obtaining a fixed digital zoom magnification ratio that is determined considering a maximum value of the degree of optical axis misalignment included in the previously stored data,
the determining of the digital zoom information comprises determining crop information of the image data, considering the fixed digital zoom magnification ratio and the obtained degree of optical axis misalignment; and
the generating of the correction image data comprises generating the correction image data by cropping the image data according to the crop information and magnifying cropped image data by the fixed digital zoom magnification ratio.
12. The method of claim 11 , wherein the determining of the digital zoom information comprises determining the crop information further considering a size of a frame of the image data.
13. The method of claim 12 , wherein the crop information comprises a location and a size of a crop area, and
the determining of the digital zoom information comprises:
determining the location of the crop area considering the size of the frame, the fixed digital zoom magnification ratio, and the degree of optical axis misalignment; and
determining the size of the crop area considering the size of the frame and the fixed digital zoom magnification ratio.
14. The method of claim 13 , wherein the location of a crop area is represented by a crop start location including a first axis component that is determined from a value calculated by Equation 1 below and a second axis component that is determined from a value calculated by Equation 2 below,
R
1
(
1
-
1
Z
)
2
+
P
1
(
Equation
1
)
R
2
(
1
-
1
Z
)
2
+
P
2
(
Equation
2
)
wherein “R 1 ” denotes the resolution of the first axis component, “P 1 ” denotes the degree of optical axis misalignment of the first axis component, “R 2 ” denotes the resolution of the second axis component, “P 2 ” denotes the degree of optical axis misalignment of the second axis component, and “Z” denotes the fixed digital zoom magnification ratio.
15. The method of claim 1 , further comprising checking whether the camera is in a real-time monitoring mode, wherein, when the camera is in a real-time monitoring mode, the method further comprises correcting the image data photographed by the camera in real time according to a fixed digital zoom magnification ratio that is determined considering a maximum value of the degree of optical axis misalignment included in the previously stored data, and outputting the correction image data to a display apparatus in real time, and
when the real-time monitoring mode is completed, the method further comprises generating the correction image data by cropping and magnifying the image data at each frame considering the degree of optical axis misalignment of the image data at each frame, by repeatedly performing the obtaining of the degree of optical axis misalignment, the determining of the digital zoom information, and the generating of the correction image data on each of a plurality of frames of the image data photographed by the camera.
16. A non-transitory computer readable storage medium for storing a computer program to perform the method of claim 1 by using a computer.
17. An apparatus for correcting an optical axis of a zoom lens, the apparatus comprising:
a correction data generation unit configured to obtain a degree of optical axis misalignment corresponding to a current zoom lens state of a camera, considering the current zoom lens state of the camera and data previously stored to define a relationship between a state of the zoom lens of the camera and the degree of optical axis misalignment, and determine digital zoom information to compensate for the degree of optical axis misalignment, considering the degree of optical axis misalignment corresponding to a current zoom lens state of the camera; and
an image data output unit configured to generate correction image data by cropping and magnifying image data photographed by the camera to correspond to the digital zoom information.