System and method for simulating fill flash in photography

• US 20030052991A1
• Filed: 09/17/2001
• Published: 03/20/2003
• Est. Priority Date: 09/17/2001
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Hubel, Paul M., Stavely, Donald J., Campbell, David K., Gennetten, K. Douglas
• Granted Patent: US 7,262,798 B2
• Time in Patent Office: Days
• US Class Current: 348/370
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 23/76 by influencing the image signals
• CPC Class Codes: H04N 5/262 Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
• CPC Class Codes: H04N 5/2621 Cameras specially adapted for the electronic generation of special effects during image pickup, e.g. digital cameras, camcorders, video cameras having integrated special effects capability

Abstract

A digital camera simulates the use of fill flash. The camera takes a series of photographs of a scene at various focus distances. The photographs are stored, along with their corresponding focus distances. The photographs are analyzed to determine the distance to objects at various locations of the scene. Regions of a final photograph are selectively adjusted in brightness based on the distance information to simulate the effect that would have resulted had fill flash been used.

Claims

1. A method of simulating fill flash in a camera system comprising the steps of:

a) determining distances from the camera to objects in a scene; and

b) taking a photograph of the scene; and

c) selectively adjusting the brightness of regions of the photograph based on the distance information.

2. The method of claim 1 wherein determining the distances from the camera to objects in the scene comprises:

a) taking a series of photographs with the camera configured to focus on objects at various distances from the camera; and

b) storing said photographs along with a focus distance for each photograph; and

c) analyzing the series of photographs and corresponding focus distances.

3. The method of claim 2 wherein the analysis of the series of photographs comprises computing a spatial contrast metric.

4. The method of claim 3 wherein determining the distances to objects at locations in the scene further comprises:

a) locating the particular photograph in the series of photographs with the spatial contrast metric indicating that objects at that location in the scene in more nearly in focus in that particular photograph than in any other in the series of photographs; and

b) identifying the distance from the camera to objects at that location in the scene as the focus distance stored in connection with that particular photograph.

5. The method of claim 1 wherein regions containing objects closer to the camera are lightened in the resulting photograph in relation to regions containing objects farther from the camera.

6. The method of claim 5 wherein regions are modified in the resulting photograph in accordance with the inverse square law.

7. A camera system which simulates fill flash by:

a) determining distances from the camera to objects in a scene; and

b) taking a photograph of the scene; and

c) selectively adjusting the brightness of regions of the photograph based on the distances.

8. The camera system of claim 7 wherein the determining the distances from the camera to objects in the scene comprises:

a) taking a series of photographs with the camera configured to focus on objects at various distances from the camera; and

b) storing said photographs along with a focus distance for each photograph; and

c) analyzing the series of photographs and corresponding focus distances to determine the object distances.

9. The camera system of claim 8 which comprises a computer separate from the camera, and wherein the series of trial photographs and their focus distances are transmitted to the separate computer for analysis and the simulation of fill flash.

10. The camera system of claim 8 wherein the analysis of the series of photographs comprises computing a spatial contrast metric.

11. The camera system of claim 8 wherein determining the distances to objects at locations in the scene further comprises:

a) locating the particular photograph in the series of photographs with the spatial contrast metric indicating that objects at that location in the scene in more nearly in focus in that particular photograph than in any other in the series of photographs; and

b) identifying the distance from the camera to objects at that location in the scene as the camera focus distance stored in connection with that particular photograph.

12. The camera system of claim 7 wherein the system lightens regions containing objects closer to the camera in the resulting photograph in relation to regions containing objects farther from the camera.

13. The camera system of claim 12 wherein the system modifies the brightness of regions in the resulting photograph in accordance with the inverse square law.

14. A camera comprising

a) means for determining distances from the camera to objects in a scene;

and

b) means for taking a photograph; and

c) means for selectively modifying the brightness of regions in the resulting photograph based on the distances.