Image processing methods and systems for fine art reproduction

• US 20060139479A1
• Filed: 12/23/2004
• Published: 06/29/2006
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: McGuire, Michael, Dicarlo, Jeffrey M., Bhachech, Miheer M., Sampat, Nitin
• Granted Patent: US 8,411,162 B2
• Time in Patent Office: Days
• US Class Current: 348/370
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature

Abstract

A method and system for processing images to, for example, capture artwork includes capturing a target image and an image of a reference. The reflectance functions of the target image are then measured. The target image is processed, using the measured reflectance functions and the captured image of the reference, to calculate a correction transform associated with the captured target image.

Claims

1. A method for processing images comprising the steps of:

capturing a target image;

capturing an image of a reference;

measuring reflectance functions of said target image; and

processing said captured target image, based on said measured reflectance functions and said captured image of said reference, to calculate a correction transform associated with said captured target image.

2. The method of claim 1, wherein said correction transform provides exposure correction and color correction for said captured target image.

3. The method of claim 1, further comprising the steps of:

determining spectral responsivity of an image capture device used to capture said target image;

determining a spectral reflectance function of said reference; and

determining spectral power distribution of light used to illuminate said target image during said step of capturing, wherein said spectral responsivity, spectral reflectance function and spectral power distribution are also used to process said target image to calculate said correction transform.

4. The method of claim 3, further comprising the step of:

determining a spectral power distribution of light which will be used to illuminate a reproduction of said target image.

5. The method of claim 1, wherein said target image is an artwork.

6. The method of claim 5, wherein said reference is a piece of canvas.

7. The method of claim 1, further comprising the step of:

storing a data structure associated with said captured target image, said data structure including data associated with pixel values of said captured target image and said correction transform.

8. The method of claim 1, wherein said step of processing said captured target image further comprises the step of:

de-skewing and cropping said captured target image.

9. The method of claim 1, wherein said step of processing said captured target further comprises the steps of:

computing, as said correction transform, a transform that produces a lowest average Δ

E between desired L*a*b* values and image capture device estimated L*a*b* responses.

10. An image processing system comprising:

an image capture device for capturing a target image and a reference; and

a processor for processing said captured target image, based on measured reflectance functions of said target image and said captured image of said reference, to calculate a correction transform associated with said captured target image.

11. The system of claim 10, wherein said correction transform provides exposure correction and color correction for said captured target image.

12. The system of claim 10, wherein said processor further uses a spectral responsivity of said image capture device, a spectral reflectance function of said reference, and a spectral power distribution of light used to illuminate said target image while being captured to calculate said correction transform.

13. The system of claim 12, wherein said processor further uses a spectral power distribution of light which will be used to illuminate a reproduction of said target image to calculate said correction transform.

14. The system of claim 10, wherein said target image is an artwork.

15. The system of claim 14, wherein said reference is a piece of canvas.

16. The system of claim 10, wherein said processor stores a data structure associated with said captured target image, said data structure including data associated with pixel values of said captured target image and said correction transform.

17. The system of claim 10, wherein processor also de-skews and crops said captured target image.

18. The system of claim 10, wherein said processor further computes, as said correction transform, a transform that produces a lowest average Δ

E between desired L*a*b* values and image capture device estimated L*a*b* responses.

19. A computer-readable medium, containing data for reproducing a plurality of images, comprising:

a plurality of data structures, each associated with one of said plurality of images, each data structure including;

a set of pixel values associated with an image; and

a corresponding correction transform associated with said image

wherein a corresponding correction transform associated with a first one of said plurality of images is different than a corresponding correction transform associated with a second one of said plurality of images.

20. The computer-readable medium of claim 19, further containing instructions which cause a processor to perform the steps of:

computing, for each corresponding correction transform, a transform that produces a lowest average Δ

E between desired L*a*b* values and image capture device estimated L*a*b* responses.

21. A system for processing images comprising the steps of:

means for capturing a target image;

means for capturing an image of a reference;

means for measuring reflectance functions of said target image; and

means for processing said captured target image, based on said measured reflectance functions and said captured image of said reference, to calculate a correction transform associated with said captured target image.