Systems and methods for detecting defective camera arrays and optic arrays
Systems and methods for detecting defective camera arrays, optic arrays and/or sensors are described. One embodiment includes capturing image data using a camera array; dividing the captured images into a plurality of corresponding image regions; identifying the presence of localized defects in any of the cameras by evaluating the image regions in the captured images; and detecting a defective camera array using the image processing system when the number of localized defects in a specific set of image regions exceeds a predetermined threshold, where the specific set of image regions is formed by: a common corresponding image region from at least a subset of the captured images; and any additional image region in a given image that contains at least one pixel located within a predetermined maximum parallax shift distance along an epipolar line from a pixel within said common corresponding image region within the given image.
1. A method for evaluating a camera's suitability as a reference camera to be used in screening the camera array having a plurality of cameras for defectiveness, the method comprising:
capturing image data of a known target using a plurality of cameras, where the known target image data forms a plurality of known target images;
identifying, using the image processing system, localized defects in each of the plurality of known target images;
identifying, using an image processing system, corresponding regions between target images captured by different cameras of the plurality of cameras, wherein the corresponding image regions between the plurality of known target images are determined by searching for correspondence along an epipolar line up to a predetermined maximum parallax shift distance, where the epipolar line is defined parallel to the relative locations of the center of a first camera and the center of a second camera;
identifying, using the image processing system, for at least one region of a target image captured by the first camera, localized defects in corresponding regions of target images captured by a set of at least one other camera of the plurality of cameras that correspond to the at least one region of the target image captured by the first camera; and
evaluating, using the image processing system, the corresponding image regions in accordance with a set of one or more localized defect criteria to determine whether the first camera is suitable as a reference camera.
2. The method of claim 1 , wherein evaluating the corresponding image regions comprises discerning whether a set of one or more defective pixels exists in a corresponding region that satisfies a criterion of the set of localized defect criteria.
3. The method of claim 2 , wherein the criterion of the set of localized defect criteria is that a number of defective pixels in the set of defective pixels within the corresponding image regions exceeds a predetermined number of defective pixels.
4. The method of claim 2 , wherein the criterion of the set of localized defect criteria is that the set of defective pixels includes a cluster of defective pixels that exceeds a predetermine size.
5. The method of claim 2 , wherein the set of defective pixels comprises at least one pixel selected from the group consisting of: a hot pixel, a bright pixel, and a dark pixel.
6. The method of claim 1 , wherein evaluating the corresponding image regions comprises:
measuring the Modulation Transfer Function (MTF) within each of the corresponding image regions; and
determining whether the MTF of each of the corresponding image regions fails to satisfy at least one criterion of the set of localized defect criteria.
7. The method of claim 6 , wherein the at least one defect criterion is that an on-axis MTF at a predetermined spatial frequency exceeds a first threshold, an off-axis tangential MTF at a predetermined spatial frequency exceeds a second threshold, and an off-axis sagittal MTF at a predetermined spatial frequency exceeds a third threshold.
8. The method of claim 5 , wherein determining whether the first camera is suitable as a reference camera comprises detecting whether a number of localized defects for the corresponding image regions according to the set of localized defect criteria is greater than zero.
9. The method of claim 5 , wherein determining whether the first camera is suitable as a reference camera comprises detecting whether a number of localized defects for the corresponding image regions according to the set of localized defect criteria is greater than a predetermined threshold, wherein the predetermined threshold is one of one, three, five, and ten.
10. The method of claim 5 further comprising:
detecting, using the image processing system, at least one localized defect in the target images captured by the first camera of the plurality of cameras;
utilizing, using the image processing system, image data corresponding to the location of the at least one localized defect that is captured by at least one other camera of the plurality of cameras when evaluating whether the first camera is suitable as the reference camera.
11. The method of claim 5 further comprising iteratively evaluating each camera of at least a subset of the plurality of cameras to determine each camera's suitability as the reference camera.
12. A non-transitory computer-readable medium including instructions that, when executed by a processing unit, evaluates a camera's suitability as a reference camera to be used in screening the camera array having a plurality of cameras for defectiveness, the instructions comprising:
retrieving captured image data of a known target that was captured using a plurality of cameras, where the known target image data forms a plurality of known target images;
identifying localized defects in each of the plurality of known target images;
identifying corresponding regions between target images captured by different cameras of the plurality of cameras, wherein the corresponding image regions between the plurality of known target images are determined by searching for correspondence along an epipolar line up to a predetermined maximum parallax shift distance, where the epipolar line is defined parallel to the relative locations of the center of a first camera and the center of a second camera;
identifying for at least one region of a target image captured by the first camera, localized defects in corresponding regions of target images captured by a set of at least one other camera of the plurality of cameras that correspond to the at least one region of the target image captured by the first camera; and
evaluating the corresponding image regions in accordance with a set of one or more localized defect criteria to determine whether the first camera is suitable as a reference camera.
13. The method of claim 12 , wherein evaluating the corresponding image regions comprises discerning whether a set of one or more defective pixels exists in a corresponding region that satisfies a criterion of the set of localized defect criteria.
14. The method of claim 12 , wherein evaluating the corresponding image regions comprises:
measuring the Modulation Transfer Function (MTF) within each of the corresponding image regions; and
determining whether the MTF of each of the corresponding image regions fails to satisfy at least one criterion of the set of localized defect criteria.
15. The method of claim 12 , wherein determining whether the first camera is suitable as a reference camera comprises detecting whether a number of localized defects for the corresponding image regions according to the set of localized defect criteria is greater than zero.
16. The method of claim 12 , wherein determining whether the first camera is suitable as a reference camera comprises detecting whether a number of localized defects for the corresponding image regions according to the set of localized defect criteria is greater than a predetermined threshold, wherein the predetermined threshold is one of one, three, five, and ten.
17. The method of claim 12 further comprising:
detecting at least one localized defect in the target images captured by the first camera of the plurality of cameras;
utilizing image data corresponding to the location of the at least one localized defect that is captured by at least one other camera of the plurality of cameras when evaluating whether the first camera is suitable as the reference camera.
18. The method of claim 12 further comprising iteratively evaluating each camera of at least a subset of the plurality of cameras to determine each camera's suitability as the reference camera.
19. A method for evaluating a camera's suitability as a reference camera to be used in screening the camera array having a plurality of cameras for defectiveness, the method comprising:
capturing image data of a known target using a plurality of cameras, where the known target image data forms a plurality of known target images;
identifying, using the image processing system, localized defects in each of the plurality of known target images;
identifying, using an image processing system, corresponding regions between target images captured by different cameras of the plurality of cameras;
identifying, using the image processing system, for at least one region of a target image captured by the first camera, localized defects in corresponding regions of target images captured by a set of at least one other camera of the plurality of cameras that correspond to the at least one region of the target image captured by the first camera; and
evaluating, using the image processing system, the corresponding image regions in accordance with a set of one or more localized defect criteria to determine whether the first camera is suitable as a reference camera, wherein evaluating the corresponding image regions comprises:
measuring the Modulation Transfer Function (MTF) within each of the corresponding image regions; and
determining whether the MTF of each of the corresponding image regions fails to satisfy at least one criterion of the set of localized defect criteria.
20. A non-transitory computer-readable medium including instructions that, when executed by a processing unit, evaluates a camera's suitability as a reference camera to be used in screening the camera array having a plurality of cameras for defectiveness, the instructions comprising:
retrieving captured image data of a known target that was captured using a plurality of cameras, where the known target image data forms a plurality of known target images;
identifying localized defects in each of the plurality of known target images;
identifying corresponding regions between target images captured by different cameras of the plurality of cameras;
identifying for at least one region of a target image captured by the first camera, localized defects in corresponding regions of target images captured by a set of at least one other camera of the plurality of cameras that correspond to the at least one region of the target image captured by the first camera; and
evaluating the corresponding image regions in accordance with a set of one or more localized defect criteria to determine whether the first camera is suitable as a reference camera, wherein evaluating the corresponding image regions comprises:
measuring the Modulation Transfer Function (MTF) within each of the corresponding image regions; and
determining whether the MTF of each of the corresponding image regions fails to satisfy at least one criterion of the set of localized defect criteria.