AUTOMATIC ILLUMINANT ESTIMATION THAT INCORPORATES APPARATUS SETTING AND INTRINSIC COLOR CASTING INFORMATION

• US 20110164150A1
• Filed: 09/24/2008
• Published: 07/07/2011
• Est. Priority Date: 09/24/2008
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Hong, Li
• Granted Patent: US 9,013,596 B2
• Time in Patent Office: Days
• US Class Current: 348/234
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control

Abstract

An image apparatus (10) for providing an estimated final illuminant of a scene (12) and subsequently providing an adjusted image (218) of a scene (12) includes a capturing system (226) and a control system (232). The capturing system (226) captures information for an input image (416) of the scene (12) while at an apparatus setting. The input image (416) is defined by a plurality of input colors. The control system (226) can compare at least one of the input colors to an illuminant database (245) that includes an illuminant gamut of observable colors for a plurality of possible illuminants, and can evaluate the apparatus setting to select one of the possible illuminants to be the estimated final illuminant. Examples of possible apparatus settings include an aperture size and an exposure time. With this design, the present invention is better able to distinguish between some possible outdoor illuminants and some possible indoor illuminants with improved accuracy. Additionally, the control system (226) can evaluate a consistency matching error for the plurality of possible illuminants to determine if the scene (12) has intrinsic color casting.

Claims

1. An image apparatus for providing an estimated final illuminant of a scene, the image apparatus comprising:

a capturing system that captures an input image of the scene, the input image including a plurality of input colors, the input image being captured while at an apparatus setting; and

a control system that compares at least one of the input colors to an illuminant database that includes an illuminant gamut of observable colors for a plurality of possible illuminants, and evaluates the apparatus setting to select one of the possible illuminants to be the estimated final illuminant.

2. The image apparatus of claim 1 wherein the control system determines a separation distance between the at least one input color and a closest observable color for each of the possible illuminants in the illuminant database to obtain a consistency matching error for each of the plurality of possible illuminants, and the control system selects the possible illuminant with the best consistency matching error as an estimated initial illuminant.

3. The image apparatus of claim 2 wherein the apparatus setting includes an aperture size and an exposure time.

4. The image apparatus of claim 2 wherein the plurality of possible illuminants includes a plurality of possible indoor illuminants and a plurality of possible outdoor illuminants, and wherein the control system evaluates the apparatus setting to determine if the apparatus setting indicates an outdoor illuminant or an indoor illuminant.

5. The image apparatus of claim 4 wherein if the estimated initial illuminant is an indoor illuminant and the apparatus setting indicates an indoor illuminant, the control system selects the estimated initial illuminant as the estimated final illuminant.

6. The image apparatus of claim 4 wherein if the estimated initial illuminant is an indoor illuminant and the apparatus setting indicates an outdoor illuminant, the control system selects an outdoor illuminant from the plurality of possible illuminants that has the best consistency matching error.

7. The image apparatus of claim 4 wherein if the estimated initial illuminant is an outdoor illuminant and the apparatus setting indicates an outdoor illuminant, the control system selects the estimated initial illuminant as the estimated final illuminant.

8. The image apparatus of claim 4 wherein if the estimated initial illuminant is an outdoor illuminant and the apparatus setting indicates an indoor illuminant, the control system selects an indoor illuminant from the plurality of possible illuminants that has the best consistency matching error.

9. The image apparatus of claim 2 wherein the control system evaluates the consistency matching error for the plurality of possible illuminants to determine if the scene has intrinsic color casting.

10. The image apparatus of claim 9 wherein the control system adjusts the estimated initial illuminant if the scene is determined to have intrinsic color casting.

11. The image apparatus of claim 1 wherein the control system performs color correction on the input image based on the estimated final illuminant.

12. An image apparatus for providing an estimated final illuminant of a scene, the image apparatus comprising:

a capturing system that captures an input image of the scene, the input image including a plurality of input colors; and

a control system that compares at least one of the input colors to an illuminant database that includes an illuminant gamut of observable colors for a plurality of possible illuminants, and evaluates if the scene has intrinsic color casting.

13. The image apparatus of claim 12 wherein the control system determines a separation distance between the at least one input color and a closest observable color for each of the possible illuminants in the illuminant database to obtain a consistency matching error for each of the plurality of possible illuminants, and the control system evaluates the consistency matching error for each of the possible illuminants to determine if the scene has intrinsic color casting.

14. The image apparatus of claim 12 wherein the control system selects the possible illuminant with the best consistency matching error as an estimated initial illuminant and wherein if the control system determines that the scene does not have intrinsic color casting, the control system selects the estimated initial illuminant as the estimated final illuminant.

15. The image apparatus of claim 12 wherein the control system selects the possible illuminant with the best consistency matching error as an estimated initial illuminant and wherein if the control system determines that the scene has intrinsic color casting, the control system selects one of the possible illuminants near the estimated initial illuminant as the estimated final illuminant.

16. The image apparatus of claim 12 wherein the control system generates a color distribution of the input image to determine a color casting of the input image.

17. The image apparatus of claim 12 wherein the control system evaluates an exposure time of the capturing system to select one of the possible illuminants to be the estimated final illuminant.

18. A method for providing an estimated final illuminant of a scene, the method comprising the steps of:

capturing an input image of the scene with a capturing system, the input image including a plurality of input colors, the input image being captured while at an apparatus setting;

comparing at least one of the input colors to an illuminant database that includes an illuminant gamut of observable colors for a plurality of possible illuminants and evaluating the apparatus setting to select one of the possible illuminants to be the estimated final illuminant with a control system.

19. The method of claim 18 wherein the step of comparing includes the step of determining a separation distance between the at least one input color and a closest observable color for each of the possible illuminants in the illuminant database to obtain a consistency matching error for each of the plurality of possible illuminants, and selecting the possible illuminant with the best consistency matching error as an estimated initial illuminant.

20. The method of claim 19 wherein the plurality of possible illuminants includes a plurality of possible indoor illuminants and a plurality of possible outdoor illuminants, and wherein the step of evaluating the apparatus setting includes determining if the apparatus setting indicates an outdoor illuminant or an indoor illuminant.

21. A method for providing an estimated final illuminant of a scene, the method comprising the steps of:

capturing an input image of the scene with a capturing system, the input image including a plurality of input colors; and

comparing at least one of the input colors to an illuminant database that includes an illuminant gamut of observable colors for a plurality of possible illuminants, and evaluating if the scene has intrinsic color casting with a control system.

22. The method of claim 21 wherein the step of comparing includes the step of determining a separation distance between the at least one input color and a closest observable color for each of the possible illuminants in the illuminant database to obtain a consistency matching error for each of the plurality of possible illuminants, and evaluating the consistency matching error for each of the possible illuminants to determine if the scene has intrinsic color casting.

23. The method of claim 22 wherein the step of comparing includes the step of selecting the possible illuminant with the best consistency matching error as an estimated initial illuminant and if the control system determines that the scene does not have intrinsic color casting, the control system selects the estimated initial illuminant as the estimated final illuminant.

24. The method of claim 22 wherein the step of comparing includes the step of selecting the possible illuminant with the best consistency matching error as an estimated initial illuminant and if the control system determines that the scene has intrinsic color casting, the control system selects one of the possible illuminants near the estimated initial illuminant as the estimated final illuminant.