High dynamic range codecs

Patent metadata

Field	Value
Publication number	US-9894374-B2
Application number	US-201615331782-A
Country	US
Kind code	B2
Filing date	Oct 21, 2016
Priority date	Jan 23, 2006
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

A method for encoding high dynamic range (HDR) images involves providing a lower dynamic range (LDR) image, generating a prediction function for estimating the values for pixels in the HDR image based on the values of corresponding pixels in the LDR image, and obtaining a residual frame based on differences between the pixel values of the HDR image and estimated pixel values. The LDR image, prediction function and residual frame can all be encoded in data from which either the LDR image of HDR image can be recreated.

First claim

The invention claimed is:

1. In an image decoder, a method to decode image data, the method comprising:
receiving image coded data, the image coded data comprising a compressed low dynamic range image, a compressed residual image, and a prediction function, wherein for input pixel values in a low dynamic range the prediction function provides corresponding predicted pixel values in a high dynamic range;
decompressing the compressed low dynamic range image to generate a reconstructed low dynamic range image;
decompressing the compressed residual image to generate a decoded residual image, wherein the decoded residual image is based on a reference high dynamic range image representing the same scene as the reconstructed low dynamic range image;
applying the prediction function to the reconstructed low dynamic range image to generate a predicted high dynamic range image; and
combining the predicted high dynamic range image with the decoded residual image data to generate an output high dynamic range image,
wherein the method is performed by one or more processors.

2. The method of claim 1 , wherein the prediction function is based on the reconstructed low dynamic range image and the reference high dynamic range image.

3. The method of claim 1 , wherein the prediction function comprises a look-up table that is indexed by pixel values in a low dynamic range.

4. The method of claim 1 , wherein the prediction function comprises a representation of a parameterized polynomial curve.

5. The method of claim I, wherein the reconstructed low dynamic range image is based on a tone-mapped representation of the reference high dynamic range image.

6. The method of claim 1 , further comprising receiving a quantization factor associated with the residual image.

7. The method of claim 6 , further comprising:
applying the quantization factor to the decoded residual image data to generate dequantized residual image data; and
combining the predicted high dynamic range image with the dequantized residual image data to generate the output high dynamic range image.

8. An apparatus for image decoding, the apparatus comprising:
a processor; and
a memory storing instructions that, when executed by the processor, configure the apparatus to:
receive image coded data, the image coded data comprising a compressed low dynamic range image, a compressed residual image, and a prediction function, wherein for input pixel values in a low dynamic range the prediction function provides corresponding predicted pixel values in a high dynamic range;
decompress the compressed low dynamic range image to generate a reconstructed low dynamic range image;
decompress the compressed residual image to generate a decoded residual image, wherein the decoded residual image is based on a reference high dynamic range image representing the same scene as the reconstructed low dynamic range image;
apply the prediction function to the reconstructed low dynamic range image to generate a predicted high dynamic range image; and
combine the predicted high dynamic range image with the decoded residual image data to generate an output high dynamic range image.

9. The apparatus of claim 8 , wherein the prediction function is based on the reconstructed low dynamic range image and the reference high dynamic range image.

10. The apparatus of claim 8 , wherein the prediction function comprises a look-up table that is indexed by pixel values in a tow dynamic range.

11. The apparatus of claim 8 , wherein the prediction function comprises a representation of a parameterized polynomial curve.

12. The apparatus of claim 8 , wherein the reconstructed low dynamic range image comprises a tone-mapped representation of the reference high dynamic range image.

13. The apparatus of claim 8 , wherein instructions further configure the apparatus to receive a quantization factor associated with the residual image.

14. The apparatus of claim 13 , wherein instructions further configure the apparatus to:
apply the quantization factor to the decoded residual image to generate a dequantized residual image; and
combine the predicted high dynamic range image with the dequantized residual image to generate the output high dynamic range image.

15. A non-transitory computer-readable storage medium having stored thereon computer-executable instructions for executing with one or more processors a method comprising: receiving image coded data, the image coded data comprising a compressed low dynamic range image, a compressed residual image, and a prediction function, wherein for input pixel values in a low dynamic range the prediction function provides corresponding predicted pixel values in a high dynamic range;
decompressing the compressed low dynamic range image to generate a reconstructed low dynamic range image;
decompressing the compressed residual image to generate a decoded residual image, wherein the decoded residual image is based on a reference high dynamic range image representing the same scene as the reconstructed low dynamic range image;
applying the prediction function to the reconstructed low dynamic range image to generate a predicted high dynamic range image; and
combining the predicted high dynamic range image with the decoded residual image data to generate an output high dynamic range image.

16. The non-transitory computer-readable storage medium of claim 15 , wherein the prediction function is based on the reconstructed low dynamic range image and the reference high dynamic range image.

17. The non-transitory computer-readable storage medium of claim 15 , wherein the prediction function comprises a look-up table that is indexed by pixel values in a low dynamic range.

18. The non-transitory computer-readable storage medium of claim 15 , wherein the prediction function comprises a representation of a parameterized polynomial curve.

19. The non-transitory computer-readable storage medium of claim 15 , wherein the reconstructed low dynamic range image comprises a tone-mapped representation of the reference high dynamic range image.

20. The non-transitory computer-readable storage medium of claim 15 , wherein instructions further configure the apparatus to receive a quantization factor associated with the residual image.

Assignees

• Max Planck Gesellschaft
• Max Planck Gesellschaft Zur Forderund Der Wss E V

Inventors

• Efremov Alexander
• Mantiuk Rafal
• Krawczyk Grzegorz
• Myszkowski Karol
• Seidel Hans Peter

Classifications

• H04N19/50 Primary

  using predictive coding (H04N19/61 takes precedence) · CPC title

• H04N19/59

  involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution · CPC title

• H04N19/63

  using sub-band based transform, e.g. wavelets · CPC title

• H04N19/187

  the unit being a scalable video layer · CPC title

• H04N19/124

  Quantisation · CPC title