Flicker band automated detection system and method

• US 8,737,832 B1
• Filed: 02/09/2007
• Issued: 05/27/2014
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Lin, Shang-Hung, He, Hu, Tjandrasuwita, Ignatius B.
• Primary Examiner(s): Perkey, W B
• Application Number:
  US11/704,507
• Time in Patent Office: 2,664 Days
• Field of Search: 396/246, 396/213, 396/234, 348/226.1
• US Class Current: 396/234
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination

Abstract

A flicker band automated detection system and method are presented. In one embodiment an incidental motion mitigation exposure setting method includes receiving image input information; performing a motion mitigating flicker band automatic detection process; and implementing exposure settings based upon results of the motion mitigating flicker band automatic detection process. The auto flicker band detection process includes performing a motion mitigating process on an illumination intensity indication. Content impacts on an the motion mitigated illumination intensity indication are minimized. The motion mitigated illumination intensity indication is binarized. A correlation of the motion mitigated illumination intensity and a reference illumination intensity frequency is established.

Claims

1. An incidental motion mitigation exposure setting method comprising:

receiving image input information;

performing a motion mitigating flicker band automatic detection process, wherein said motion mitigating flicker band automatic detection process includes;

performing a motion mitigating process on an illumination intensity indication, wherein said motion mitigating process includes image down sampling and averaging pixel intensity readings over a plurality of pixel rows;

minimizing content impacts on said illumination intensity indication results of said motion mitigating process;

binarizing said motion mitigated illumination intensity indication; and

finding a correlation of said motion mitigated illumination intensity and a reference illumination intensity frequency; and

implementing exposure settings based upon results of said motion mitigating flicker band automatic detection process.

2. The incidental motion mitigation exposure setting method of claim 1 wherein said motion mitigating flicker band automatic detection process automatically identifies an illumination frequency.

3. The incidental motion mitigation exposure setting method of claim 2 wherein said exposure settings are implemented based upon said identified illumination frequency.

4. The incidental motion mitigation exposure setting method of claim 1 wherein said image input information is received from a CMOS imaging apparatus.

5. The incidental motion mitigation exposure setting method of claim 1 further comprising setting up a sensor timing frame that is not a multiple of an illumination intensity reference frequency.

6. The incidental motion mitigation exposure setting method of claim 1 wherein a correlation score is utilized to establish said correlation and said correlation score is assigned based upon the following manipulation:

7. A flicker band automatic detection imaging system comprising:

a lens for focusing light reflected from an object;

a light sensor for sensing light from said lens and converting said light into electrical digital image information;

a shutter for controlling a length of time said light is permitted to pass from said lens to said light sensor;

a processor for processing said digital image information forwarded from said light sensor and directing motion mitigated flicker band automatic detection and mitigation, wherein said motion mitigating flicker band automatic detection and mitigation includes;

performing a motion mitigating process on an illumination intensity indication, wherein said motion mitigating process includes image down sampling and averaging pixel intensity readings over a plurality of pixel rows;

minimizing content impacts on said illumination intensity indication results of said motion mitigating process;

binarizing said motion mitigated illumination intensity indication; and

finding a correlation of said motion mitigated illumination intensity and a reference illumination intensity frequency; and

a memory for storing digital image information and instructions for directing said processor, including motion mitigated flicker band automatic detection instructions for performing flicker band automatic detection and mitigation.

8. A flicker band automatic detection imaging system of claim 7 wherein said motion mitigating auto flicker band detection process automatically identifies an illumination intensity frequency and establishes a corresponding exposure setting.

9. A flicker band automatic detection imaging system of claim 7 wherein said processor controls said length of time said shutter permits light to pass from said lens to said light sensor based upon said established exposure setting.

10. A flicker band automatic detection imaging system of claim 7 wherein content neutralized illumination intensity values are utilized by said processor.

11. A flicker band automatic detection imaging system of claim 7 wherein said directing motion mitigated flicker band automatic detection identifies an illumination intensity frequency based upon a known reference illumination intensity frequency.

12. A motion mitigating flicker band automatic detection process comprising

performing a motion mitigating process on an illumination intensity indication;

minimizing content impacts on an said motion mitigated illumination intensity indication;

binarizing said motion mitigated illumination intensity indication; and

finding a correlation of said motion mitigated illumination intensity and a reference illumination intensity freqeuncy.

13. A motion mitigating flicker band automatic detection process of claim 12 wherein said motion mitigation process includes:

performing image sub-sampling; and

averaging illumination intensity values from a plurality of pixel rows of said resulting sub-sampled image.

14. A motion mitigating flicker band automatic detection process of claim 12 wherein a number of downsampled pixel rows is maintained above a minimum that is greater than a video frame rate.

15. A motion mitigating flicker band automatic detection process of claim 12 wherein minimizing content impacts on said illumination intensity indication includes subtracting illumination intensity values of a first frame from illumination intensity values of a second frame.

16. A motion mitigating flicker band automatic detection process of claim 12 wherein said correlation score is assigned based upon the following manipulation:

18. A motion mitigating flicker band automatic detection process of claim 13 wherein said reliable down-sampled pixels include pixels associated with smooth well lit surface.

19. A motion mitigating flicker band automatic detection process of claim 12 wherein binarizing said illumination intensity indication includes comparing each entry value in a subtraction buffer with a moving average value and if a row in the subtraction buffer as a value larger than the mean the values change to one, otherwise the values change to negative one.

17. A motion mitigating flicker band automatic detection process of 13 further comprising selecting reliable down-sampled pixels for said averaging.

20. An incidental motion mitigation exposure setting method comprising:

receiving image input information;

performing a motion mitigating flicker band automatic detection process, wherein said motion mitigating flicker band automatic detection process includes;

performing a motion mitigating process on an illumination intensity indication;

minimizing content impacts on said illumination intensity indication results of said motion mitigating process;

binarizing said motion mitigated illumination intensity indication; and

finding a correlation of said motion mitigated illumination intensity and a reference illumination intensity frequency; and

implementing exposure settings based upon results of said motion mitigating flicker band automatic detection process.

21. An incidental motion mitigation exposure setting method of claim 20 wherein said motion mitigation process includes:

performing image sub-sampling; and

averaging illumination intensity values from a plurality of pixel rows of said resulting sub-sampled image.

22. An incidental motion mitigation exposure setting method of claim 20 wherein a number of downsampled pixel rows is maintained above a minimum that is greater than a video frame rate.

23. An incidental motion mitigation exposure setting method of claim 20 wherein minimizing content impacts on said illumination intensity indication includes subtracting illumination intensity values of a first frame from illumination intensity values of a second frame.

24. An incidental motion mitigation exposure setting method of claim 20 wherein a correlation score is utilized to establish said correlation and said correlation score is assigned based upon the following manipulation:

25. An incidental motion mitigation exposure setting method of claim 20 further comprising selecting reliable down-sampled pixels for said averaging.

26. An incidental motion mitigation exposure setting method of claim 20 wherein said reliable down-sampled pixels include pixels associated with smooth well lit surface.

27. A incidental motion mitigation exposure setting method of claim 20 wherein subtraction values are equal to subtracting illumination intensity values of a first frame from illumination intensity values of a second frame and binarizing said illumination intensity indication includes comparing said subtraction values with a moving average value and if a row of said subtraction values is larger than the mean the subtraction values change to one, otherwise the subtraction values change to negative one.