Method and Apparatus for Block-Based Compression of Light-field Images

• US 20120183232A1
• Filed: 03/23/2012
• Published: 07/19/2012
• Est. Priority Date: 04/29/2008
• Status: Active Grant

• Current Assignee: Adobe Inc.
• Original Assignee: Sevket Derin Babacan, Todor G. Georgiev
• Inventors: Babacan, Sevket Derin, Georgiev, Todor G.
• Granted Patent: US 8,401,316 B2
• Time in Patent Office: Days
• US Class Current: 382/232
• CPC Class Codes: G02B 27/0075 with means for altering, e.g. increasing, the depth of field or depth of focus
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/597 specially adapted for multi-view video sequence encoding
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/90 using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
• CPC Class Codes: H04N 5/772 the recording apparatus and the television camera being placed in the same enclosure
• CPC Class Codes: H04N 5/91 Television signal processing therefor
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

A method and apparatus for the block-based compression of light-field images. Light-field images may be preprocessed by a preprocessing module into a format that is compatible with the blocking scheme of a block-based compression technique, for example JPEG. The compression technique is then used to compress the preprocessed light-field images. The light-field preprocessing module reshapes the angular data in a captured light-field image into shapes compatible with the blocking scheme of the compression technique so that blocking artifacts of block-based compression are not introduced in the final compressed image. Embodiments may produce compressed 2D images for which no specific light-field image viewer is needed to preview the full light-field image. Full light-field information is contained in one compressed 2D image.

Claims

1. A computer-implemented method, comprising:

obtaining a light-field image, wherein the light-field image comprises multiple microimages, wherein the dimensions of the microimages are different than blocking dimensions used by a block-based compression technique;

generating a block in a preprocessed light-field image from each microimage in the light-field image, wherein each block contains light-field information from a corresponding microimage, and wherein the dimensions of each block are the same as the blocking dimensions used by the block-based compression technique;

compressing the preprocessed light-field image in accordance with the block-based compression technique to generate a compressed light-field image; and

storing the compressed light-field image to a storage medium.

2. The method as recited in claim 1, wherein said generating a block in a preprocessed light-field image from each microimage in the light-field image comprises, for each microimage:

cropping the microimage to extract a region of pixels from the microimage, wherein the dimensions of the region are smaller than the dimensions of the block; and

interpolating the cropped region of pixels to generate pixel values for the pixels in the corresponding block from the pixel values of the pixels in the cropped region.

3. The method as recited in claim 2, wherein said interpolating the cropped region of pixels comprises solving the Laplace equation to generate the pixel values for the pixels in the corresponding block from the pixel values of the pixels in the cropped region.

4. The method as recited in claim 1, wherein the dimensions of the blocks are eight pixels by eight pixels.

5. The method as recited in claim 1, further comprising, prior to said generating a block in a preprocessed light-field image from each microimage in the light-field image, normalizing the light-field image in accordance with a calibration image.

6. The method as recited in claim 1, wherein the light-field image is captured with a plenoptic camera, and wherein each microimage is approximately circular.

7. The method as recited in claim 6, further comprising, prior to said generating a block in a preprocessed light-field image from each microimage in the light-field image:

locating each microimage in the light-field image; and

extracting the located microimages from the light-field image.

8. The method as recited in claim 1, wherein the block-based compression technique compresses the preprocessed light-field image in accordance with the JPEG (Joint Photographic Experts Group) compression standard.

9. The method as recited in claim 1, wherein the compressed light-field image is viewable using any application that is capable of accessing files compressed using the block-based compression technique.

10. A system, comprising:

at least one processor; and

a memory comprising program instructions, wherein the program instructions are executable by the at least one processor to;

obtain a light-field image, wherein the light-field image comprises multiple microimages, wherein the dimensions of the microimages are different than blocking dimensions used by a block-based compression technique;

generate a block in a preprocessed light-field image from each microimage in the light-field image, wherein each block contains light-field information from a corresponding microimage, and wherein the dimensions of each block are the same as the blocking dimensions used by the block-based compression technique;

compress the preprocessed light-field image in accordance with the block-based compression technique to generate a compressed light-field image; and

store the compressed light-field image to a storage device.

11. The system as recited in claim 10, wherein, to generate a block in a preprocessed light-field image from each microimage in the light-field image, the program instructions are executable by the at least one processor to, for each microimage:

crop the microimage to extract a region of pixels from the microimage, wherein the dimensions of the region are smaller than the dimensions of the block; and

interpolate the cropped region of pixels to generate pixel values for the pixels in the corresponding block from the pixel values of the pixels in the cropped region.

12. The system as recited in claim 11, wherein, to interpolate the cropped region of pixels, the program instructions are executable by the at least one processor to solve the Laplace equation to generate the pixel values for the pixels in the corresponding block from the pixel values of the pixels in the cropped region.

13. The system as recited in claim 10, wherein the dimensions of the blocks are eight pixels by eight pixels.

14. The system as recited in claim 10, wherein the program instructions are executable by the at least one processor to, prior to said generate a block in a preprocessed light-field image from each microimage in the light-field image, normalize the light-field image in accordance with a calibration image for the light-field camera.

15. The system as recited in claim 10, wherein the light-field image is captured with a plenoptic camera, and wherein each microimage is approximately circular.

16. The system as recited in claim 15, wherein the program instructions are executable by the at least one processor to, prior to said generate a block in a preprocessed light-field image from each microimage in the light-field image:

locate each microimage in the light-field image; and

extract the located microimages from the light-field image.

17. The system as recited in claim 10, wherein the block-based compression technique compresses the preprocessed light-field image in accordance with the JPEG (Joint Photographic Experts Group) compression standard.

18. A computer-readable storage medium storing program instructions, wherein the program instructions are computer-executable to implement:

obtaining a light-field image, wherein the light-field image comprises multiple microimages, wherein the dimensions of the microimages are different than blocking dimensions used by a block-based compression technique;

generating a block in a preprocessed light-field image from each microimage in the light-field image, wherein each block contains light-field information from a corresponding microimage, and wherein the dimensions of each block are the same as the blocking dimensions used by the block-based compression technique;

compressing the preprocessed light-field image in accordance with the block-based compression technique to generate a compressed light-field image; and

storing the compressed light-field image to a storage medium.

19. The computer-readable storage medium as recited in claim 18, wherein, in said generating a block in a preprocessed light-field image from each microimage in the light-field image, the program instructions are computer-executable to implement, for each microimage:

cropping the microimage to extract a region of pixels from the microimage, wherein the dimensions of the region are smaller than the dimensions of the block; and

interpolating the cropped region of pixels to generate pixel values for the pixels in the corresponding block from the pixel values of the pixels in the cropped region.

20. The computer-readable storage medium as recited in claim 19, wherein, in said interpolating the cropped region of pixels, the program instructions are computer-executable to implement solving the Laplace equation to generate the pixel values for the pixels in the corresponding block from the pixel values of the pixels in the cropped region.

21-25. -25. (canceled)