Hysteresis in image processing algorithms

• US 6,943,832 B2
• Filed: 03/22/2001
• Issued: 09/13/2005
• Est. Priority Date: 03/22/2001
• Status: Expired due to Term

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Poplin, Dwight
• Primary Examiner(s): Moe, Aung
• Application Number:
  US09/815,019
• Publication Number:
  US 20040201718A1
• Time in Patent Office: 1,636 Days
• Field of Search: 348/222.1, 348/254, 348/674, 348/241, 348/362, 348/296, 348/223.1, 348/222
• US Class Current: 348/222.1
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control

Abstract

A method and system that utilizes hysteresis in image processing algorithms to minimize interframe noise in video frames is provided. The method includes receiving a video frame and determining a measurement in the video frame, wherein the measurement is associated with an image control feature. The method also includes providing a target value and a tolerance, and calculating an error value using the measurement and the target value. The method further includes comparing the error value to the tolerance, and in response to the error value being greater than the tolerance, adjusting the image control feature. The system includes a video frame stored in a storage medium and a module coupled to the storage medium. The module is operable to determine a measurement in the video frame, wherein the measurement is associated with an image control feature. The module is also operable to calculate an error value using the measurement and a target value, and compare the error value to a tolerance. In response to the error value being greater than the tolerance, the module is further operable to adjust the image control feature.

Claims

1. A method for minimizing interframe noise in an image processing system, the method comprising:

providing a target setting for an image control feature in the image processing system;

providing a storage unit configured to store a state information associated with the image control feature, the state information being either a first state or a second state;

providing a tolerance for the image control feature, the tolerance being a first value in the first state, the tolerance being a second value in the second state, the first value being a narrow tolerance and the second value being a wide tolerance;

receiving a frame of data corresponding to a video frame;

determining an image control feature measurement from the frame of data, the image control measurement being associated with the image control feature;

calculating an error value using the image control feature measurement and the target setting;

determining if the error value exceeds the tolerance;

in response to determining that the error value exceeds the tolerance, setting the state information to the first state and converging the image control feature measurement toward the target setting; and

in response to determining that the error value does not exceed the tolerance, setting the state information to the second state and maintaining the image control feature.

2. The method of claim 1, wherein the first state in a not converged state.

3. The method of claim 1, wherein the second state is a converged state.

4. The method of claim 1, wherein the image control feature comprising an automatic exposure function.

5. The method of claim 1, wherein the image control feature comprising an automatic white balance function.

6. The method of claim 5, wherein the image control feature is selected from the group consisting of a red channel of the automatic white balance function and blue channel of the automatic white balance function.

7. The method of claim 1, wherein the image control feature comprising a tonemapping function.

8. The method of claim 1, wherein the target setting being a target luminance.

9. The method of claim 1, wherein the target setting being a maximum green value measured in the frame of data.

10. The method of claim 1, wherein the image control feature measurement being an average luminance measured in the frame of data.

11. The method of claim 1, wherein the image control feature measurement is selected from the group consisting of a maximum red value measured in the frame of data and a maximum blue value measured in the frame of data.

12. The method of claim 1, wherein converging the image control feature measurement toward the target setting comprises adjusting an exposure time.

13. The method of claim 1, wherein converging the image control feature measurement toward the target setting is selected from the group consisting of adjusting a red multiplier and adjusting a blue multiplier.

14. The method of claim 1, wherein the error value being a percentage variance of the image control feature measurement from the target setting.

15. The method of claim 1, wherein the frame of data being received from a video capture system.

16. The method of claim 1, wherein the frame of data being received from a storage device coupled to the image processing system.

17. The method of claim 1 further comprising capturing the video frame.

18. An image processing system comprising:

a first storage unit configured to store one or more target settings for one or more image control features, the first storage unit storing a target setting for an image control feature;

a second storage unit configured to store a state information associated with the image control feature, the state information being either a first state or a second state;

a third storage unit configured to store a tolerance for the image control feature, the tolerance being a first value in the first state, the tolerance being a second value in the second state, the first value being a narrow tolerance and the second value being a wide tolerance; and

a module coupled to the first, second, and third storage units, the module operable to receive a frame of data corresponding to a video frame, the module operable to determine an image control feature measurement from the frame of data, the image control feature measurement being associated with the image control feature, the module operable to calculate an error value using the image control feature measurement and the target setting, the module also operable to determine if the error value exceeds the tolerance, wherein;

in response to determining that the error value exceeds the tolerance, the module operable to set the state information to the first state and converge the image control feature measurement toward the target setting;

in response to determining that the error value does not exceed the tolerance, the module operable to set the state information to the second state and maintain the image control feature.

19. The system of claim 18 further comprising a second module coupled to the module, the second module operable to determine a statistic from the frame of data, the statistic being used to determine the image control feature measurement.

20. The system of claim 18, wherein the module and the first, second, and third storage units are implemented in one or more image processing chips.

21. The system of claim 18, wherein the error value being a percentage variance of the image control feature measurement from the target setting.

22. The system of claim 18 comprising a sensor component coupled to the module, the sensor component operable to capture the frame of data.

23. The system of claim 18, wherein the module and the first, second, and third storage units are implemented in a computer.

24. The system of claim 18, wherein the module and the first second, and third storage units are implemented in a video player.

25. The system of claim 18, wherein the module is operable to, in response to the error value not being greater than the tolerance, maintain the image control feature.

26. The system of claim 18, wherein the image control feature comprising an automatic exposure function.

27. The system of claim 18, wherein the image control feature comprising an automatic white balance function.

28. The system of claim 18, wherein the target value being a target luminance.

29. The system of claim 18, wherein the target value being a maximum green value measured in the video frame.

30. The system of claim 18, wherein the measurement being an average luminance measured in the video frame.

31. The system of claim 18, wherein the measurement is selected from the group consisting of a maximum red value measured in the video frame and a maximum blue value measured in the video frame.

32. The system of claim 18, wherein adjust the image control feature comprises an adjustment to an exposure time.

33. The system of claim 18, wherein adjust the image control feature is selected from the group consisting of an adjustment to a red multiplier and an adjustment to a blue multiplier.

34. The system of claim 18, wherein the error value being a percentage variance of the measurement from the target value.