Adjusting digital image exposure and tone scale

• US 7,821,570 B2
• Filed: 11/30/2005
• Issued: 10/26/2010
• Est. Priority Date: 11/30/2005
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Eastman Kodak Company
• Inventors: Gallagher, Andrew C., Ray, Lawrence A., Fielding, Gabriel, Cahill, Nathan D., Gindele, Edward B.
• Primary Examiner(s): Ometz; David L
• Assistant Examiner(s): Berhan; Ahmed A
• Application Number:
  US11/290,049
• Publication Number:
  US 20070126921A1
• Time in Patent Office: 1,791 Days
• Field of Search: 348/362, 348/371, 348/364, 348/207.99, 348/366, 348/365, 348/348, 348/208.14, 348/363, 348/370
• US Class Current: 348/364
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/30201 Face
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors

Abstract

A method of adjusting exposure of a digital camera based on range information, including a digital camera capturing a first digital image at a selected exposure of a scene having objects; providing range information having two or more range values indicating the distance from the digital camera to objects in the scene; using the range information and pixel values of the captured digital image to determine an exposure adjustment amount for the selected exposure; and applying the exposure adjustment amount to the digital image to produce a second digital image with adjusted exposure.

Claims

1. A method of adjusting exposure of a digital camera based on range information, comprising:

(a) a digital camera capturing a first digital image at a selected exposure of a scene having objects;

(b) providing range information having two or more range values indicating the distance from the digital camera to objects in the scene;

(c) applying a spatial filter to the range information to detect range edges, and using the range edges and pixel values of the captured digital image to determine an exposure adjustment amount for the selected exposure; and

(d) applying the exposure adjustment amount to the digital image to produce a second digital image with adjusted exposure.

2. The method of claim 1, wherein step b further includes:

(i) using the range edges to determine a set of weighting coefficients; and

(ii) using the weighting coefficients and the digital image to determine an exposure adjustment amount.

3. The method claim 2, wherein the weighting coefficients indicate the relative importance within the digital image based on the range edges.

4. The method of claim 2, further including:

(e) adjusting the tone scale of the second digital image based on range edges.

5. A method of adjusting exposure of a captured digital image of a scene having objects, comprising:

(a) providing range information having two or more range values indicating the distance of objects in the scene;

(b) applying a spatial filter to the range information to detect range edges, and using the range edges and pixel values of the captured digital image to determine an exposure adjustment amount for the selected exposure; and

(c) applying the exposure adjustment amount to the captured digital image to produce a second digital image with adjusted exposure.

6. The method of claim 5, wherein step b) further includes:

(i) using the range edges-to determine a set of weighting coefficients; and

(ii) using the weighting coefficients and the digital image to determine a exposure adjustment amount.

7. The method claim 6, wherein the weighting coefficients indicate the relative importance within the digital image based on the range edges.

8. The method of claim 5, further including:

d) adjusting the tone scale of the second digital image based on range edges.

9. The method of claim 8, wherein step d) includes:

i) dividing the captured digital image into a pedestal signal and a texture signal;

(ii) applying a tone scale function to the pedestal signal to produce a modified pedestal signal, wherein range information is used in step i; and

(iii) adding the texture signal to the modified pedestal signal to produce the second digital image with adjusted tone scale.

10. A method of adjusting tone scale of a captured digital image of a scene having objects, comprising:

(a) providing range information having two or more range values indicating the distance of objects in the scene;

(b) applying a spatial filter to the range information to detect range edges, and using the range edges and pixel values of the captured digital image to determine a tone scale adjustment; and

(c) applying the tone scale adjustment to the captured digital image to produce a second digital image with adjusted tone scale.

11. The method of claim 10, wherein step b includes:

(i) dividing the captured digital image into a pedestal signal and a texture signal;

(ii) applying a tone scale function to the pedestal signal to produce a modified pedestal signal, wherein range information is used in step(i) or in step(ii) or both; and

(iii) adding the texture signal to the modified pedestal signal to produce the second digital image with adjusted tone scale.

12. The method of claim 11, wherein step b) i) includes filtering a pixel of the captured digital image using weights derived from an analysis of range values from the range image.