Using a residual image formed from a clipped limited color gamut digital image to represent an extended color gamut digital image

• US 6,301,393 B1
• Filed: 01/21/2000
• Issued: 10/09/2001
• Est. Priority Date: 01/21/2000
• Status: Expired due to Term

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Eastman Kodak Company
• Inventors: Spaulding, Kevin E., Woolfe, Geoffrey J., Joshi, Rajan L.
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): ROSSI, JEFFREY A
• Application Number:
  US09/489,367
• Time in Patent Office: 627 Days
• Field of Search: 382/240, 345/431, 345/434, 345/153-155
• US Class Current: 382/240
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77

Abstract

A method for representing a digital image having color values with an extended color gamut in a storage color space having a limited color gamut comprising the steps of: adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image; representing the limited color gamut digital image in the storage color space; determining a clipped limited color gamut digital image in which highly quantized regions in the limited color gamut digital image have been clipped; determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image; and associating the residual image with the limited color gamut digital image in the storage color space such that the associated residual image and the limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image.

Claims

1. A method for representing a digital image having color values with an extended color gamut in a storage color space having a limited color gamut, comprising the steps of:

a) adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image;

b) representing the limited color gamut digital image in the storage color space;

c) determining a clipped limited color gamut digital image in which portions of the limited color gamut digital image have been clipped to eliminate color values where the limited color gamut digital image is highly quantized;

d) determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image; and

e) associating the residual image with the limited color gamut digital image in the storage color space such that the associated residual image and the limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image.

2. The method of claim 1 in which the clipped portions of the limited color gamut digital image are the portions of the limited color gamut digital image that have a high level of quantization error thereby reducing large serrations in the residual image.

3. The method of claim 1 where the storage color space is a particular device dependent color space.

4. The method of claim 3 where the storage color space is a video RGB color space.

5. The method of claim 1 where the storage color space is a particular limited color gamut color space.

6. The method of claim 1 where the clipped limited color gamut digital image is determined from the limited color gamut digital image using a look-up table.

7. The method of claim 1 where the extended color gamut digital image has a larger luminance dynamic range than the limited color gamut digital image.

8. The method of claim 7 where the step of adjusting the color values of the extended color gamut digital image to determine the limited color gamut digital image includes applying a tone scale function to reduce the luminance dynamic range of the image.

9. The method of claim 8 where the clipped limited color gamut digital image is determined by clipping portions of the limited color gamut digital image corresponding to low-slope regions of the tone scale function.

10. The method of claim 1 where the limited color gamut digital image in the storage color space is stored in a digital image file using a digital storage medium.

11. The method of claim 10 where the residual image is stored as meta-data in the digital image file.

12. The method of claim 10 where a data compression technique is applied to the residual image before it is stored so that it uses a smaller amount of digital storage memory.

13. The method of claim 10 where the limited color gamut digital image is stored in the digital image file, and the residual image is stored in a separate associated digital image file.

14. The method of claim 1 further including the step of using the residual image together with the limited color gamut digital image in the storage color space to form a reconstructed extended color gamut digital image.

15. The method of claim 1 further including the step of using the residual image together with the limited color gamut digital image in the storage color space to form a digital image appropriate for display on an output device having a color gamut different that the limited color gamut.

16. The method of claim 4 further including the step of previewing the digital image by displaying the limited color gamut digital image in the storage color space on a video display.

17. The method of claim 1 where the extended color gamut digital image originates from a scan of a photographic negative.

18. The method of claim 1 where the extended color gamut digital image originates from a scan of a photographic transparency.

19. The method of claim 1 where the extended color gamut digital image originates from a scan of a photographic print.

20. The method of claim 1 where the extended color gamut digital image originates from a digital camera.

21. The method of claim 1 where the extended color gamut digital image originates from an original piece of artwork.

22. A method for representing and manipulating a digital image with an extended color gamut using a storage color space having a limited color gamut comprising the steps of:

a) adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image;

b) representing the limited color gamut digital image in the storage color space;

c) determining a clipped limited color gamut digital image in which portions of the limited color gamut digital image have been clipped to eliminate color values where the limited color gamut digital image is highly quantized;

d) determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image;

e) associating the residual image with the limited color gamut digital image in the storage color space such that the associated residual image and the limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image;

f) specifying a desirable modification to the image; and

g) using the residual image together with the limited color gamut digital image in the storage color space and the specified desirable modification to the image to produce a modified digital image.

23. The method of claim 22 in which the clipped portions of the limited color gamut digital image are the portions of the limited color gamut digital image that have a high level of quantization error thereby reducing large serrations in the residual image.

24. The method of claim 22 where the desirable modification is interactively user specified.

25. The method of claim 22 where the desirable modification is determined by applying an automatic algorithm to the digital image.

26. A method for representing a digital image having color values with an extended color gamut in a storage color space having a limited color gamut comprising the steps of:

a) adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image;

b) representing the limited color gamut digital image in the storage color space;

c) compressing the limited color gamut digital image in the storage color space;

d) decompressing the limited color gamut digital image in the storage color space to form an decompressed limited color gamut digital image;

e) determining a clipped limited color gamut digital image in which portions of the decompressed limited color gamut digital image have been clipped to eliminate color values where the limited color gamut digital image is highly quantized;

f) determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image; and

g) associating the residual image with the compressed limited color gamut digital image in the storage color space such that the associated residual image and the compressed limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image.

27. The method of claim 26 in which the clipped portions of the limited color gamut digital image are the portions of the limited color gamut digital image that have a high level of quantization error thereby reducing large serrations in the residual image.

28. A computer program product, comprising a computer readable storage medium, for representing a digital image having color values with an extended color gamut in a storage color space having a limited color gamut having a computer program stored thereon for performing the steps of:

a) adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image;

b) representing the limited color gamut digital image in the storage color space;

c) determining a clipped limited color gamut digital image in which portions of the limited color gamut digital image have been clipped to eliminate color values where the limited color gamut digital image is highly quantized;

d) determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image; and

e) associating the residual image with the limited color gamut digital image in the storage color space such that the associated residual image and the limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image.

29. A computer program product for representing and manipulating a digital image with an extended color gamut using a storage color space having a limited color gamut, and having a computer readable storage medium with a computer program stored thereon for performing the steps:

a) adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image;

b) representing the limited color gamut digital image in the storage color space;

c) determining a clipped limited color gamut digital image in which portions of the limited color gamut digital image have been clipped to eliminate color values where the limited color gamut digital image is highly quantized;

d) determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image;

e) associating the residual image with the limited color gamut digital image in the storage color space such that the associated residual image and the limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image;

f) specifying a desirable modification to the image; and

g) using the residual image together with the limited color gamut digital image in the storage color space and the specified desirable modification to the image to produce a modified digital image.

30. A computer program product, comprising a computer readable storage medium, for representing a digital image having color values with an extended color gamut in a storage color space having a limited color gamut having a computer program stored thereon for performing the steps of:

a) adjusting the color values of the extended color gamut digital image to fit within the limited color gamut to form a limited color gamut digital image;

b) representing the limited color gamut digital image in the storage color space;

c) compressing the limited color gamut digital image in the storage color space;

d) decompressing the limited color gamut digital image in the storage color space to form an decompressed limited color gamut digital image;

e) determining a clipped limited color gamut digital image in which portions of the decompressed limited color gamut digital image have been clipped to eliminate color values where the limited color gamut digital image is highly quantized;

f) determining a residual image representing a difference between the extended color gamut digital image and the clipped limited color gamut digital image; and

g) associating the residual image with the compressed limited color gamut digital image in the storage color space such that the associated residual image and the compressed limited color gamut digital image in the storage color space are adapted to be used to form a reconstructed extended color gamut digital image.