Techniques for radial fall-off correction

• US 20070236594A1
• Filed: 03/31/2006
• Published: 10/11/2007
• Est. Priority Date: 03/31/2006
• Status: Abandoned Application

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Khan, Moinul, Nguyen, Tung, Hasan, Zafar
• Application Number:
  US11/394,405
• Publication Number:
  US 20070236594A1
• Time in Patent Office: Days
• US Class Current: 348/335
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 25/61 the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4"

Abstract

A system, apparatus, method and article to perform radial fall-off correction are described. The apparatus may include a coefficient determination module and a fall-off correction module. The coefficient determination module determines a fall-off correction coefficient for a pixel of an image sensor, and the fall-off correction module corrects the pixel based on an intensity value of the pixel and the fall-off correction coefficient. The fall-off correction coefficient may be based on one or more stored coefficient values, where the one or more coefficient values correspond to a squared distance between the pixel and a center position of the image sensor. In this manner, improvements in computational efficiency and reductions in implementation complexity are attained. Other embodiments may be described and claimed.

Claims

1. An apparatus, comprising:

a coefficient determination module to determine a fall-off correction coefficient for a pixel of an image sensor, the fall-off correction coefficient based on one or more of a plurality of stored coefficient values, wherein the one or more stored coefficient values correspond to a squared distance between the pixel and a center position of the image sensor; and

a fall-off correction module to correct the pixel based on an intensity value of the pixel and the fall-off correction coefficient.

2. The apparatus of claim 1, wherein the coefficient determination module comprises a squared distance determination module to determine the squared distance between the pixel and the center position of the image sensor.

3. The apparatus of claim 1, further comprising:

a memory to store the plurality of stored coefficient values in a coefficient look-up table (LUT), the LUT having addresses for the plurality of coefficient values, wherein the addresses are based on corresponding squared distances from the center position of the image sensor.

4. The apparatus of claim 3, wherein the squared distances corresponding to the addresses are separated at substantially equal intervals.

5. The apparatus of claim 3, wherein the memory further comprises an interpolation LUT to store interpolation factors between consecutive entries in the coefficient LUT.

6. The apparatus of claim 1, wherein the coefficient determination module comprises a scaling module to adjust the fall-off correction coefficient based on an optical focal length associated with the image sensor.

7. The apparatus of claim 1, further comprising the image sensor.

8. The apparatus of claim 1, further comprising a display to display images corresponding to pixel values provided by the image sensor.

9. The apparatus of claim 1, further comprising a communications interface to send image signals to a remote device, the image signals corresponding to pixel values provided by image sensor.

10. The apparatus of claim 1, further comprising a memory to store the plurality of stored coefficient values.

11. An apparatus, comprising:

a coefficient determination module to determine a fall-off correction coefficient for a pixel of an image sensor, the fall-off correction coefficient based on one or more of a plurality of stored coefficient values, wherein the one or more stored coefficient values correspond to a squared distance between the pixel and a center position of the image sensor; and

a fall-off correction module to correct the pixel based on an intensity value of the pixel and the fall-off correction coefficient; and

a scaling module to adjust the fall-off correction coefficient based on an optical focal length associated with the image sensor;

wherein the plurality of stored coefficient values corresponds to a plurality of squared distances separated at substantially equal intervals.

12. A method, comprising:

storing a plurality of fall-off correction coefficient values, each coefficient value corresponding to one of a plurality of squared distances from a center position of an image sensor;

determining a squared distance between a pixel of the image sensor and the center position of the image sensor;

accessing one or more of the stored coefficient values based on the determined squared distance; and

determining a fall-off correction coefficient for the pixel based on the one or more accessed fall-off correction coefficient values.

13. The method of claim 12, further comprising:

receiving an intensity value corresponding to the pixel; and

multiplying the intensity value with the determined fall-off correction coefficient.

14. The method of claim 12, wherein the plurality of squared distances are separated at substantially equal intervals.

15. The method of claim 12:

wherein accessing the one or more correction coefficient values comprises accessing first and second stored coefficient values; and

wherein determining the fall-off correction coefficient comprises interpolating between the first and second stored coefficient values.

16. The method of claim 12, further comprising:

adjusting the determined fall-off correction coefficient based on an optical focal length associated with the image sensor.

17. An article comprising a machine-readable storage medium containing instructions that if executed enable a system to:

store a plurality of fall-off correction coefficient values, each coefficient value corresponding to one of a plurality of squared distances from a center position of an image sensor;

determine a squared distance between a pixel of the image sensor and the center position of the image sensor;

access one or more of the stored coefficient values based on the determined squared distance; and

determine a fall-off correction coefficient for the pixel based on the one or more accessed fall-off correction coefficient values.

18. The article of claim 17, further comprising instructions that if executed enable the system to store the plurality of coefficient values in a coefficient look-up table (LUT), the LUT having addresses for the plurality of coefficients, wherein the addresses are based on corresponding squared distances from the center position of the image sensor that are separated at substantially equal intervals.

19. The article of claim 17, further comprising instructions that if executed enable the system to adjust the determined fall-off correction coefficient based on an optical focal length associated with the image sensor.

20. The article of claim 17, further comprising instructions that if executed enable the system to determine the fall-off correction coefficient for the pixel based on an interpolation between first and second stored coefficient values.