Virtual lens simulation for video and photo cropping
In a video capture system, a virtual lens is simulated when applying a crop or zoom effect to an input video. An input video frame is received from the input video that has a first field of view and an input lens distortion caused by a lens used to capture the input video frame. A selection of a sub-frame representing a portion of the input video frame is obtained that has a second field of view smaller than the first field of view. The sub-frame is processed to remap the input lens distortion to a desired lens distortion in the sub-frame. The processed sub-frame is the outputted.
1. A system that simulates image distortion of a virtual lens in a video, the system comprising:
one or more processors; and
a non-transitory computer-readable storage medium storing instructions that when executed cause the one or more processors to perform steps including:
accessing input images, the input images including fields of view of a scene, the input images depicting the scene with an input lens distortion centered in the fields of view based on lens characteristics of a lens through which the input images are captured;
selecting reduced fields of view of the scene smaller than the fields of view of the input images, the reduced fields of view including lens distortion effects as a function of the input lens distortion present in the fields of view of the input images, positions of the reduced fields of view within the fields of view of the input images, and size of the reduced fields of view; and
generating output images based on the lens distortion effects in the reduced fields of view and a desired lens distortion, the output images including portions of the input images within the reduced fields of view, the desired lens distortion being consistent with the lens characteristics of the lens, wherein generation of the output images include remapping of the input lens distortion centered in the fields of view of the input images to the desired lens distortion centered in the reduced fields of view to transform the lens distortion effects present in the reduced fields of view to the desired lens distortion such that portions of the scene depicted in the output images appear to have been captured using the reduced fields of view.
2. The system of claim 1 , wherein image stabilization is applied to the input images.
3. The system of claim 1 , wherein the reduced fields of view are selected based on metadata associated with the input images.
4. The system of claim 3 , wherein the metadata indicates motion of a camera that captured the input images.
5. The system of claim 3 , wherein the metadata indicates orientation of a camera that captured the input images.
6. The system of claim 1 , wherein the output images are used as video frames of an output video.
7. The system of claim 6 , wherein remapping of the input lens distortion centered in the fields of view of the input images to the desired lens distortion centered in the reduced fields of view results in the output video having consistent frame-to-frame lens characteristics.
8. The system of claim 7 , wherein the positions of the reduced fields of view within the fields of view of the input images simulate virtual re-pointing of a camera using the reduced fields of view.
9. The system of claim 8 , wherein the reduced fields of view are selected in post-processing after capture of the input images, the selection of the reduced fields of view in the post-processing performed using a post-processing tool.
10. The system of claim 8 , wherein the reduced fields of view are selected during capture of the input images.
11. A method for simulating image distortion of a virtual lens in a video, the method comprising:
accessing input images, the input images including fields of view of a scene, the input images depicting the scene with an input lens distortion centered in the fields of view based on lens characteristics of a lens through which the input images are captured;
selecting reduced fields of view of the scene smaller than the fields of view of the input images, the reduced fields of view including lens distortion effects as a function of the input lens distortion present in the fields of view of the input images, positions of the reduced fields of view within the fields of view of the input images, and size of the reduced fields of view; and
generating output images based on the lens distortion effects in the reduced fields of view and a desired lens distortion, the output images including portions of the input images within the reduced fields of view, the desired lens distortion being consistent with the lens characteristics of the lens, wherein generation of the output images include remapping of the input lens distortion centered in the fields of view of the input images to the desired lens distortion centered in the reduced fields of view to transform the lens distortion effects present in the reduced fields of view to the desired lens distortion such that portions of the scene depicted in the output images appear to have been captured using the reduced fields of view.
12. The method of claim 11 , wherein image stabilization is applied to the input images.
13. The method of claim 11 , wherein the reduced fields of view are selected based on metadata associated with the input images.
14. The method of claim 13 , wherein the metadata indicates motion of a camera that captured the input images.
15. The method of claim 13 , wherein the metadata indicates orientation of a camera that captured the input images.
16. The method of claim 11 , wherein the output images are used as video frames of an output video.
17. The method of claim 16 , wherein remapping of the input lens distortion centered in the fields of view of the input images to the desired lens distortion centered in the reduced fields of view results in the output video having consistent frame-to-frame lens characteristics.
18. The method of claim 17 , wherein the positions of the reduced fields of view within the fields of view of the input images simulate virtual re-pointing of a camera using the reduced fields of view.
19. The method of claim 18 , wherein the reduced fields of view are selected in post-processing after capture of the input images, the selection of the reduced fields of view in the post-processing performed using a post-processing tool.
20. The method of claim 18 , wherein the reduced fields of view are selected during capture of the input images.