Systems and methods for synthesizing images from image data captured by an array camera using restricted depth of field depth maps in which depth estimation precision varies

• US 9,519,972 B2
• Filed: 03/12/2014
• Issued: 12/13/2016
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: FotoNation Limited (Adeia Inc.)
• Original Assignee: Kip Peli P1 LP
• Inventors: Venkataraman, Kartik, Nisenzon, Semyon, Chatterjee, Priyam, Molina, Gabriel
• Primary Examiner(s): Ye, Lin
• Assistant Examiner(s): Cowan, Euel
• Application Number:
  US14/207,254
• Publication Number:
  US 20140267243A1
• Time in Patent Office: 1,007 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06T 1/20 Processor architectures; Processor configuration, e.g. pipelining
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10052 Images from lightfield camera
• CPC Class Codes: G06T 7/557 from light fields, e.g. from plenoptic cameras
• CPC Class Codes: H04N 13/106 Processing image signals for multi-view video sequence encoding H04N19/597
• CPC Class Codes: H04N 13/271 wherein the generated image signals comprise depth maps or disparity maps
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals

Abstract

Systems and methods are described for generating restricted depth of field depth maps. In one embodiment, an image processing pipeline application configures a processor to: determine a desired focal plane distance and a range of distances corresponding to a restricted depth of field for an image rendered from a reference viewpoint; generate a restricted depth of field depth map from the reference viewpoint using the set of images captured from different viewpoints, where depth estimation precision is higher for pixels with depth estimates within the range of distances corresponding to the restricted depth of field and lower for pixels with depth estimates outside of the range of distances corresponding to the restricted depth of field; and render a restricted depth of field image from the reference viewpoint using the set of images captured from different viewpoints and the restricted depth of field depth map.

Claims

1. An image processing system, comprising:

a processor;

memory containing a set of images captured from different viewpoints and an image processing pipeline application;

wherein the image processing pipeline application configures the processor to;

determine a range of distances corresponding to a restricted depth of field; and

generate a restricted depth of field depth map from the reference viewpoint using the set of images captured from different viewpoints, where depth estimation precision is higher for pixels with depth estimates within the range of distances corresponding to the restricted depth of field and lower for pixels with depth estimates outside of the range of distances corresponding to the restricted depth of field;

wherein the image processing pipeline application further configures the processor to generate a restricted depth of field depth map by;

performing a disparity search with respect to a given pixel location using the set of images captured from different viewpoints;

wherein the disparity search is performed using a greater density of depth samples within the range of distances corresponding to the restricted depth of field and a lower density of depth samples for distances outside the range of distances corresponding to the restricted depth of field.

2. The image processing system of claim 1, wherein the image processing pipeline application further configures the processor to automatically determine the range of distances corresponding to a restricted depth of field.

3. The image processing system of claim 2, wherein the image processing pipeline application further configures the processor to automatically determine the range of distances corresponding to the restricted depth of field by determining a distance to a surface of a scene object using the set of images captured from different viewpoints.

4. The image processing system of claim 3, wherein the image processing pipeline application further configures the processor to determine a distance to a surface of a scene object using the set of images captured from different viewpoints by:

generating an initial depth map and a confidence map from at least a portion of the set of images captured from different viewpoints, where the confidence map indicates the reliability of pixel depth estimates in the initial depth map; and

determining the depth of the surface of the scene object based upon at least one pixel depth estimate within the initial depth map marked as confident within the confidence map.

5. The image processing system of claim 3, wherein the image processing pipeline application further configures the processor to receive a user instruction identifying a surface of a scene object by:

generating a preview image from the set of images captured from different viewpoints, where the preview image includes a user interface cue; and

identifying a surface of a scene object visible within the set of images captured from different viewpoints based upon the location of the user interface cue.

6. The image processing system of claim 3, wherein the image processing pipeline application further configures the processor to determine the range of distances corresponding to the restricted depth of field based upon user instructions.

7. The image processing system of claim 1, wherein the image processing pipeline application further configures the processor to generate a restricted depth of field depth map by:

generating an initial depth map using the set of images captured from different viewpoints;

determining pixel locations with depth estimates from the initial depth map indicating that the pixel locations are likely to have depths within the range of distances corresponding to the restricted depth of field;

generating higher depth estimation precision depth estimates for at least some of the pixel locations that are likely to have depths within the range of distances corresponding to the restricted depth of field using the set of images captured from different viewpoints; and

generating a restricted depth of field depth map using at least some of the depth estimates from the initial depth map and at least some of the higher depth estimation precision depth estimates.

8. The image processing system of claim 7, wherein the image processing pipeline application further configures the processor to generate an initial depth map by:

downsampling at least some of the images in the set of images captured from different viewpoints to obtain a set of lower spatial resolution images; and

determining a low spatial resolution depth map using the set of lower spatial resolution images.

9. The image processing system of claim 8, wherein the image processing pipeline application further configures the processor to determine a low spatial resolution depth map using the set of lower spatial resolution images by:

performing a disparity search with respect to a given pixel location using the set of lower spatial resolution images;

wherein the disparity search is performed by searching a first set of disparities.

10. The image processing system of claim 9, wherein the image processing pipeline application further configures the processor to generate the higher precision depth estimates by:

performing a disparity search with respect to a given pixel location using the set of images captured from different viewpoints;

wherein the disparity search is performed by searching a second set of disparities; and

wherein a search performed using the second set of disparities provides greater depth estimation precision within the range of distances corresponding to the restricted depth of field than the precision of a depth estimate obtained within the same range of distances by a search performed using the first set of disparities.

11. The image processing system of claim 10, wherein the first set of disparities is not uniformly distributed with respect to disparity.

12. The image processing system of claim 10, wherein the first set of disparities is uniformly distributed with respect to disparity.

13. The image processing system of claim 10, wherein the second set of disparities is not uniformly distributed with respect to disparity.

14. The image processing system of claim 10, wherein the second set of disparities is uniformly distributed with respect to disparity.

15. The image processing system of claim 7, wherein the image processing pipeline application further configures the processor to:

generate an initial confidence map for the initial depth map; and

determine pixel locations with depth estimates from the initial depth map indicating that the pixel locations are likely to have depths within the range of distances corresponding to the restricted depth of field based upon the depth estimate for the pixel location in the initial depth map and the confidence of the depth estimate for the pixel location indicated by the initial confidence map.

16. The image processing system of claim 7, wherein the image processing pipeline application further configures the processor to determine pixel locations with depth estimates from the initial depth map indicating that the pixel locations are likely to have depths within the range of distances corresponding to the restricted depth of field based upon the depth estimate for the pixel location and a determination that the pixel is not contained within a textureless region.

17. The image processing system of claim 1, wherein the image processing pipeline application further configures the processor to render a restricted depth of field image from the reference viewpoint using the set of images captured from different viewpoints and the restricted depth of field depth map by:

compositing pixels from the set of images captured from different viewpoints having depth estimates outside the range of distances corresponding to the restricted depth of field by applying scene dependent geometric corrections determined based upon the depth estimates of the composited pixels in the restricted depth of field depth map; and

performing super-resolution processing using pixels from the set of images captured from different viewpoints having depth estimates within the range of distances corresponding to the restricted depth of field to synthesize portions of the rendered image at a spatial resolution that is greater than the spatial resolution of the individual images in the set of images captured from different viewpoints.

18. The image processing system of claim 17, wherein the image processing pipeline application further configures the processor to perform super-resolution processing by:

performing fusion of pixels from the set of images captured from different viewpoints having depth estimates within the range of distances corresponding to the restricted depth of field to obtain a set of fused pixels by applying scene dependent geometric corrections determined based upon the depth estimates of the fused pixels in the restricted depth of field depth map; and

interpolating the set of fused pixels to achieve increases in spatial resolution.

19. The image processing system of claim 17, wherein:

the super-resolution processing synthesizes portion of the rendered image at a spatial resolution that is greater than the spatial resolution of the individual images in the set of images captured from different viewpoints by a super-resolution factor; and

depth estimation precision for pixels with depth estimates within the range of distances corresponding to the restricted depth of field is at least a precision with respect to disparity corresponding to the spatial resolution of the pixels of at least one of the images in the set of images captured from different viewpoints divided by the super-resolution factor.

20. The image processing system of claim 17, wherein the image processing pipeline application further configures the processor to:

generate a restricted depth of field depth map by;

generating an initial depth map using the set of images captured from different viewpoints by;

downsampling at least some of the images in the set of images captured from different viewpoints to obtain a set of lower spatial resolution images; and

determining a low spatial resolution depth map using the set of lower spatial resolution images;

determining pixel locations with depth estimates from the initial depth map indicating that the pixel locations are likely to have depths within the range of distances corresponding to the restricted depth of field;

generating higher depth estimation precision depth estimates for at least some of the pixel locations that are likely to have depths within the range of distances corresponding to the restricted depth of field using the set of images captured from different viewpoints; and

generating a restricted depth of field depth map using at least some of the depth estimates from the initial depth map and at least some of the higher depth estimation precision depth estimates; and

composite pixels from the set of images captured from different viewpoints and pixels from the set of lower spatial resolution images by applying scene dependent geometric corrections to the pixels from the set of lower spatial resolution images determined based upon the depth estimates in the initial depth map.

21. The image processing system of claim 1, wherein:

the set of images captured from different viewpoints comprises a plurality of subsets of images captured from different viewpoints in a plurality of different color channels;

the image processing pipeline application further configures the processor to render a restricted depth of field image from the reference viewpoint using the set of images captured from different viewpoints and the restricted depth of field depth map by;

rendering images from each of the plurality of different color channels using the restricted depth of field depth map; and

compositing the rendered image from each of the plurality of different color channels to form a full color reduced depth of field image.

22. The image processing system of claim 1, wherein the reference viewpoint is a virtual viewpoint.

23. An array camera, comprising:

an array of cameras configured to capture image data forming a set of images captured from different viewpoints;

a processor;

memory containing an image processing pipeline application;

wherein the image processing pipeline application configures the processor to;

capture a set of images captured from different viewpoints using the array of cameras;

store the set of images captured from different viewpoints in memory;

determine a desired range of distances corresponding to a restricted depth of field; and

generate a restricted depth of field depth map from the reference viewpoint using the set of images captured from different viewpoints, where depth estimation precision is higher for pixels with depth estimates within the range of distances corresponding to the restricted depth of field and lower for pixels with depth estimates outside of the range of distances corresponding to the restricted depth of field;

determine a range of distances corresponding to a restricted depth of field;

wherein the image processing pipeline application further configures the processor to generate a restricted depth of field depth map by;

performing a disparity search with respect to a given pixel location using the set of images captured from different viewpoints;

wherein the disparity search is performed using a greater density of depth samples within the range of distances corresponding to the restricted depth of field and a lower density of depth samples for distances outside the range of distances corresponding to the restricted depth of field.

24. The array camera of claim 23, further comprising:

a display;

wherein the image processing pipeline application further configures the processor to generate a preview image from the set of images captured from different viewpoints and display the preview image via the display.

25. The array camera of claim 24, wherein:

the display provides a touch user interface; and

the image processing pipeline application further configures the processor to determine a desired restricted depth of field based upon a touch gesture received via the touch user interface during the display of the preview image.

26. The array camera of claim 23, wherein:

at least one of the cameras in the array of cameras includes an autofocus module configured to determine an autofocus distance; and

the image processing pipeline application configures the processor to determine a restricted depth of field based upon the autofocus distance.

27. The array camera of claim 23, wherein the array of cameras includes a π

filter group comprising and a 3×

3 array of cameras comprising;

a reference camera at the center of the 3×

3 array of cameras;

two red color cameras located on opposite sides of the 3×

3 array of cameras;

two blue color cameras located on opposite sides of the 3×

3 array of cameras; and

four green color cameras surrounding the reference camera.

28. An array camera, comprising:

an array of cameras configured to capture image data forming a set of images captured from different viewpoints, where the array of cameras includes a π

filter group comprising and a 3×

3 array of cameras comprising;

a reference camera at the center of the 3×

3 array of cameras;

two red color cameras located on opposite sides of the 3×

3 array of cameras;

two blue color cameras located on opposite sides of the 3×

3 array of cameras; and

four green color cameras surrounding the reference camera;

a processor;

memory containing an image processing pipeline application;

wherein the image processing pipeline application configures the processor to;

capture a set of video sequences from different viewpoints using the array of cameras, where each video sequence comprises a sequence of frames of video and corresponding frames from the set of video sequences captured from different viewpoints form sets of frames of video captured from different viewpoints;

store the set of video sequences captured from different viewpoints in memory;

for a set of frames of video captured from different viewpoints;

determine a desired focal plane distance and a range of distances corresponding to a restricted depth of field for a frame of video rendered from a reference viewpoint corresponding to the viewpoint of the reference camera;

generate a restricted depth of field depth map from the reference viewpoint using the set of frames of video captured from different viewpoints by;

generating an initial depth map using the set of frames of video captured from different viewpoints by;

 

downsampling at least some of the frames of video in the set of frames of video captured from different viewpoints to obtain a set of lower spatial resolution images; and

 

determining a low spatial resolution depth map using the set of lower spatial resolution images;

 

determining pixel locations with depth estimates from the initial depth map indicating that the pixel locations are likely to have depths within the range of distances corresponding to the restricted depth of field;

 

generating higher depth estimation precision depth estimates for at least some of the pixel locations that are likely to have depths within the range of distances corresponding to the restricted depth of field using the set of images captured from different viewpoints; and

 

generating a restricted depth of field depth map using at least some of the depth estimates from the initial depth map and at least some of the higher depth estimation precision depth estimates; and

 

rendering a restricted depth of field frame of video from the reference viewpoint using the set of frames of video captured from different viewpoints and the restricted depth of field depth map by;

 

compositing pixels from the set of frames of video captured from different viewpoints having depth estimates outside the range of distances corresponding to the restricted depth of field by applying scene dependent geometric corrections determined based upon the depth estimates of the composited pixels in the restricted depth of field depth map; and

 

performing super-resolution processing using pixels from the set of frames of video captured from different viewpoints having depth estimates within the range of distances corresponding to the restricted depth of field to synthesize portions of the rendered restricted depth of field frame of video at a spatial resolution that is greater than the spatial resolution of the individual frames of video in the set of frames of video captured from different viewpoints.