Efficient lens re-distortion

Patent metadata

Field	Value
Publication number	US-9818201-B2
Application number	US-201414579507-A
Country	US
Kind code	B2
Filing date	Dec 22, 2014
Priority date	Dec 22, 2014
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

Methods and systems efficiently apply known distortion, such as of a camera and lens, to source image data to produce data of an output image with the distortion. In an embodiment, an output image field is segmented into regions so that on each segment the distortion function is approximately linear, and segmentation data is stored in a quadtree. The distortion function is applied to the segmented image field to produce a segmented rendered distortion image (SRDI) and a corresponding look-up table. To distort a source image, a location in the output image field is selected, and the uniquely colored segment at the same location in the SRDI is found. The look-up table provides the local linear inverse of the distortion function, which is applied to determine from where in the source image to take image texture data for the distorted output image.

First claim

What is claimed is:

1. A method of processing an image, the method comprising:
receiving, by a processor, a distorted image captured with a lens that generates distortion in the image;
generating, with the processor, a corrected image by applying a distortion correction algorithm to correct for distortion in the distorted image;
storing, in a computer-readable medium operatively coupled to the processor, a segmented rendered distortion image (SRDI) representing how the distortion in the distorted image is generated, wherein the SRDI is generated by recursively subdividing the SRDI into segments until a distortion function for each of the segments has an approximate inverse function that can be readily calculated; and
thereafter, generating, with the processor, a re-distorted image using the SRDI to re-distort the corrected image.

2. The method claim 1 further comprising editing the corrected image by adding one or more undistorted computer graphic objects to the corrected image prior to generating the re-distorted image.

3. The method of claim 1 further comprising storing a plurality of entries, each of the plurality of entries including information that identifies a portion of the corrected image, a portion of the distorted image corresponding to the portion of the corrected image, and an approximate inverse function that can be readily calculated to re-distort the portion of the corrected image.

4. The method of claim 3 wherein the plurality of entries is stored in a lookup table.

5. The method of claim 4 wherein the lookup table comprises a quadtree.

6. The method of claim 1 wherein a total number of the segments is significantly less than a total number of pixels in the corrected image.

7. The method of claim 6 wherein each of the segments of the SRDI is represented by a color value that is unique within the SRDI.

8. The method of claim 1 , wherein the approximate inverse function for a segment is determined to be readily calculated when the corresponding distortion function is determined to be approximately linear when restricted to the segment.

9. A non-transitory, computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:
receiving a distorted image captured with a lens that generates distortion in an image;
generating a corrected image by applying a distortion correction algorithm to correct for distortion in the distorted image;
storing a segmented rendered distortion image (SRDI) representing how the lens generates the distortion in the distorted image, wherein the SRDI is generated by recursively subdividing the SRDI into segments until a distortion function for each of the segments has an approximate inverse function that can be readily calculated; and
generating a re-distorted image using the SRDI to re-distort the corrected image.

10. The non-transitory, computer-readable medium of claim 9 , further comprising additional instructions that cause the one or more processors to perform additional operations comprising:
editing the corrected image by adding one or more undistorted computer graphic objects to the corrected image prior to generating the re-distorted image.

11. The non-transitory, computer-readable medium of claim 9 , further comprising additional instructions that cause the one or more processors to perform additional operations comprising:
storing a plurality of entries, each of the plurality of entries including information that identifies a portion of the corrected image, a portion of the distorted image corresponding to the portion of the corrected image, and an approximate inverse function that can be readily calculated to re-distort the portion of the corrected image.

12. The non-transitory, computer-readable medium of claim 9 , wherein:
a total number of the segments is significantly less than a total number of pixels in the corrected image.

13. The non-transitory, computer-readable medium of claim 9 , wherein each of the segments of the SRDI is represented by a color value that is unique within the SRDI.

14. The non-transitory, computer-readable medium of claim 9 , wherein the approximate inverse function for a segment is determined to be readily calculated when the corresponding distortion function is determined to be approximately linear when restricted to the segment.

15. A computer system comprising:
one or more processors;
one or more memory devices comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
receiving a distorted image captured with a lens that generates distortion in an image;
generating a corrected image by applying a distortion correction algorithm to correct for distortion in the distorted image;
storing a segmented rendered distortion image (SRDI) representing how the lens generates the distortion in the distorted image, wherein the SRDI is generated by recursively subdividing the SRDI into segments until a distortion function for each of the segments has an approximate inverse function that can be readily calculated; and
generating a re-distorted image using the SRDI to re-distort the corrected image.

16. The computer system of claim 15 , wherein the one or more memory devices further comprises additional instructions that cause the one or more processors to perform additional operations comprising:
editing the corrected image by adding one or more undistorted computer graphic objects to the corrected image prior to generating the re-distorted image.

17. The computer system of claim 15 , wherein the one or more memory devices further comprises additional instructions that cause the one or more processors to perform additional operations comprising:
storing a plurality of entries, each of the plurality of entries including information that identifies a portion of the corrected image, a portion of the distorted image corresponding to the portion of the corrected image, and an approximate inverse function that can be readily calculated to re-distort the portion of the corrected image.

18. The computer system of claim 15 , wherein:
a total number of the segments is significantly less than a total number of pixels in the corrected image.

19. The computer system of claim 15 , wherein each of the segments of the SRDI is represented by a color value that is unique within the SRDI.

20. The computer system of claim 15 , wherein the approximate inverse function for a segment is determined to be readily calculated when the corresponding distortion function is determined to be approximately linear when restricted to the segment.

Assignees

• Lucasfilm Entertainment Co Ltd
• Lucasfilm Entertainment Co Ltd

Inventors

• Mallet Ronald

Classifications

• H04N23/81

  for suppressing or minimising disturbance in the image signal generation · CPC title

• G06T2207/20021

  Dividing image into blocks, subimages or windows · CPC title

• G06T3/0018

  Physics · mapped topic

• G06T7/0081 Primary

  Physics · mapped topic

• G06T5/006

  Physics · mapped topic