Methods, systems and apparatuses for motion detection using auto-focus statistics

• US 20080291333A1
• Filed: 05/24/2007
• Published: 11/27/2008
• Est. Priority Date: 05/24/2007
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Micron Technology, Inc.
• Inventors: Subbotin, Igor, Mokhnatyuk, Alexander
• Granted Patent: US 8,233,094 B2
• Time in Patent Office: Days
• US Class Current: 348/700
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6811 based on the image signal

Abstract

Methods, systems and apparatuses for the detection of motion using statistics data already available within an imager, such as sharpness scores or brightness values. The method includes obtaining at least two sets of statistics data for respective image frames which include corresponding windows; initializing a motion counter; determining, for each window, a relative difference value for the particular window; comparing the relative difference value to a first threshold. If the relative difference value is greater than the first threshold, the method increments the motion counter; and determines if there is motion by comparing the value of the motion counter to a second threshold. The motion detection may further take into account the relative importance of certain areas of the image frame.

Claims

1. A method for detecting motion using an imager comprising:

obtaining motion sensitive statistics data for a plurality of image frames, wherein each image frame comprises a plurality of corresponding windows;

for each window, determining a relative difference value for a particular window using motion sensitive statistics data from first and second image frames;

determining a number of times the relative difference value is greater than a first threshold; and

determining if there is motion by comparing the number of times the relative difference value is greater than the first threshold to a second threshold.

2. The method of claim 1, wherein the motion sensitive statistics data includes at least two sets of motion sensitive statistics data, one set for each of respective image frames.

3. The method of claim 1, wherein the motion sensitive statistics data comprises one of sharpness scores, brightness values or a combination sharpness scores and brightness values.

6. The method of claim 1, wherein the first threshold represents an amount of change for a single window between image frames, wherein the second threshold represents a maximum number of windows for which the relative difference value is greater than the first threshold, above which there is motion, and wherein the relative difference value is computed as an absolute value of the difference between the motion sensitive statistics data of the first and second image frames for a particular window divided by a maximum of the motion sensitive statistics data of the first and second image frames for the particular window.

4-5. -5. (canceled)

7-8. -8. (canceled)

9. A method for detecting motion using an imager comprising:

obtaining motion sensitive statistics data for a plurality of image frames, wherein each image frame comprises a plurality of corresponding windows;

for each window, determining a relative difference value for a particular window using motion sensitive statistics data from first and second image frames;

determining a motion score, wherein the motion score is a summation, for each window for which the relative difference value is greater than a first threshold, of a motion variable multiplied by a weight factor corresponding to each window; and

determining if there is motion by comparing the value of the motion score to a second threshold.

11. The method of claim 9, wherein the weight factors are based on the relative importance of the particular window to which it corresponds.

12. The method of claim 9, wherein the weight factor for a window near the center of the image frame is higher than the weight factor for a window near a periphery of the image frame.

13. The method of claim 9, wherein the motion sensitive statistics data comprises one of sharpness scores, brightness values or a combination sharpness scores and brightness values.

16. The method of claim 9, wherein the first threshold represents an amount of change for a single window between image frames.

17. The method of claim 9, wherein the second threshold represents a maximum value of the motion score, above which there is motion.

18. The method of claim 9, wherein the relative difference value is computed as an absolute value of the difference between the motion sensitive statistics data of the first and second image frames for a particular window divided by a maximum of the motion sensitive statistics data of the first and second image frames for the particular window.

10. (canceled)

14-15. -15. (canceled)

19. An imaging device comprising:

a pixel array, the pixel array outputting a plurality of pixel values; and

an image processing unit coupled to the pixel array, the imaging processing unit being operable to detect motion in a scene represented by the plurality of pixel values, wherein motion is detected using changes in at least one of a sharpness score and a brightness value in different image frames.

20. The imaging device of claim 19, wherein the image processing unit further comprises a statistics engine and the at least one of sharpness score and brightness value is computed by the statistics engine.

21. The imaging device of claim 19, wherein motion is detected using a combination of the sharpness score and brightness value.

22. The imaging device of claim 19, wherein each image frame comprises a plurality of windows, and wherein the at least one of sharpness score and brightness value is determined for each window of each image frame.

23. The imaging device of claim 22, wherein the image processing unit is further operable to:

for each window, determine a relative difference value for a particular window using the at least one of sharpness score and brightness value from first and second image frames;

determine a number of times the relative difference value is greater than a first threshold; and

determine if there is motion by comparing the number of times the relative difference value is greater than the first threshold to a second threshold.

24. The imaging device of claim 22, wherein the image processing unit is further operable to:

for each window, determine a relative difference value for a particular window using the at least one of sharpness score and brightness value from first and second image frames;

determine a motion score, wherein the motion score is a summation, for each window for which the relative difference value is greater than a first threshold, of a motion variable multiplied by a weight factor corresponding to each window; and

determine if there is motion by comparing the value of the motion score to a second threshold.

25. The imaging device of claim 24, wherein the weight factor for a window near the center of the image frame is higher than the weight factor for a window near a periphery of the image frame.

26. An imaging system comprising:

a lens;

a pixel array for capturing image frames received through the lens; and

an image processing circuit which is operable to detect motion in the captured image frames, wherein the motion detection comprises;

obtaining motion sensitive statistics data for a plurality of image frames, wherein each image frame comprises a plurality of corresponding windows;

for each window, determining a relative difference value for a particular window using motion sensitive statistics data from first and second image frames;

determining a number of times the relative difference value is greater than a first threshold; and

determining if there is motion by comparing the number of times the relative difference value is greater than the first threshold to a second threshold.

30. The imaging system of claim 26, wherein the relative difference value is computed as an absolute value of the difference between the motion sensitive statistics data of the first and second image frames for a particular window divided by a maximum of the motion sensitive statistics data of the first and second image frames for the particular window.

31. The imaging system of claim 26, wherein the motion sensitive statistics data comprises one of information from a statistics engine located in the image processing unit and information obtained for an auto-focus operation of the imaging system.

27-29. -29. (canceled)

32. (canceled)

33. An imaging system comprising:

a lens;

a pixel array for capturing image frames received through the lens; and

an image processing circuit which is operable to detect motion in the captured image frames, wherein the motion detection comprises;

obtaining motion sensitive statistics data for a plurality of image frames, wherein each image frame comprises a plurality of corresponding windows;

for each window, determining a relative difference value for a particular window using motion sensitive statistics data from first and second image frames;

determining a motion score, wherein the motion score is a summation, for each window for which the relative difference value is greater than a first threshold, of a motion variable multiplied by a weight factor corresponding to each window; and

determining if there is motion by comparing the value of the motion score to a second threshold.

37. The imaging system of claim 33, wherein the weight factor for a window near the center of the image frame is higher than the weight factor for a window near a periphery of the image frame.

38. The imaging system of claim 33, wherein the relative difference value is computed as an absolute value of the difference between the motion sensitive statistics data of the first and second image frames for a particular window divided by a maximum of the motion sensitive statistics data of the first and second image frames for the particular window.

39. The imaging system of claim 33, wherein the motion sensitive statistics data comprises one of information from a statistics engine located in the image processing unit and information obtained for an auto-focus operation of the imaging system.

34-36. -36. (canceled)

40. (canceled)