Efficient detection of constant regions of an image

• US 7,881,538 B2
• Filed: 09/22/2008
• Issued: 02/01/2011
• Est. Priority Date: 03/06/2006
• Status: Expired due to Fees

• Current Assignee: Marvell International Technology, Ltd. (Marvell Technology Group Limited)
• Original Assignee: Marvell International Technology, Ltd. (Marvell Technology Group Limited)
• Inventors: Shoen, Jay R.
• Primary Examiner(s): Bhatnagar; Anand
• Application Number:
  US12/284,407
• Publication Number:
  US 20090022404A1
• Time in Patent Office: 862 Days
• Field of Search: 382/100, 382/181, 382/190, 382/192, 382/193, 382/194, 382/195, 382/199, 382/201, 382/205, 382/206, 382/209, 382/216, 382/217, 382/221, 382/225, 382260-266, 382/271, 35842601-42616, 358/448, 358/453, 358/462, 358/463, 358/464, 358/465
• US Class Current: 382/195
• CPC Class Codes: G06T 7/11 Region-based segmentation

Abstract

A technique that improves image analysis efficiency by reducing the number of computations needed to detect constant regions. Constant region detection according to the present techniques includes determining whether an image analysis window at a current position contains a constant region by analyzing a new line of pixels in the image analysis window if a pixel at a predetermined location in the image analysis window in the current position has a value equal to a pixel at the predetermined location from a previous position of the image analysis window. Analyzing only the new line of pixels saves the computational time that would otherwise go into analyzing all of the pixels in the image analysis window.

Claims

1. A method for detecting a constant region of an image frame, comprising:

at a previous position of an image analysis window, determining, with a processor, whether the image analysis window contains a constant region;

should the determining whether the image analysis window contains a constant region result in a determination that the image analysis window contains a constant region, then the following process is performed;

shifting, with a processor, the image analysis window to a current position so that the image analysis window includes a new line of pixels from the image frame in comparison to the previous position of the image analysis window, wherein an entire area of the image analysis window at the previous position is a first constant region of pixels and wherein a constant region is defined as a region wherein all pixels contained therein are substantially similar in value;

determining, with a processor, whether the entire area of the image analysis window at the current position is a second constant region by analyzing a first pixel at a predetermined location in the image analysis window at the current position, the predetermined location being defined relative to a boundary of the image analysis window, wherein the analyzing comprises;

determining, with a processor, if the first pixel has a value equal to a value of a second pixel at the predetermined location relative to the boundary of the image analysis window when the image analysis window was at the previous position,

if the value of the first pixel has a value equal to the value of the second pixel, then analyzing, with a processor, only the new line of pixels to determine if the second constant region is present.

2. The method of claim 1, wherein the predetermined location is a center of the image analysis window relative to the boundary of the image analysis window.

3. The method of claim 1, further comprising detecting the first constant region at the previous position of the image analysis window.

4. The method of claim 1, wherein analyzing the new line of pixels comprises comparing a set of values of the new line of pixels to a value of the second pixel at the predetermined location when the image analysis window was at the previous position.

5. The method of claim 1, wherein shifting the image analysis window comprises shifting the image analysis window by one pixel.

6. The method of claim 1, further comprising analyzing all of the pixels in the image analysis window when the value of the first pixel at the predetermined location does not equal the value of the second pixel at the predetermined location.

7. An image processing system comprising:

means for holding an image frame; and

means for

     1) determining that an entire area of an image analysis window that included a plurality of pixels of the image frame at a previous position is a first constant region of pixels and wherein a constant region is defined as a region wherein all pixels contained therein are substantially similar in value and

     2) detecting whether an entire area of the image analysis window at a current position is a second constant region of the image frame by analyzing a first pixel at a predetermined location in the image analysis window at the current position, predetermined location being defined relative to a boundary of the image analysis window, wherein the analyzing comprises;

determining whether the first pixel has a value equal to a value of a second pixel at the predetermined location in the image analysis window relative to the boundary of the image analysis window when the image analysis window was at the previous position;

if the value of the first pixel has a value equal to the value of the second pixel, then analyzing only a new line of pixels present in the image analysis window at the current position when compared with the image analysis window at the previous position to determine if the second constant region is present; and

if the value of the first pixel does not have a value equal to the value of the second pixel, then analyzing all pixels present in the image analysis window at the current position to determine if the second constant region is present.

8. The image processing system of claim 7, wherein the predetermined location is a center of the image analysis window relative to the boundary of the image analysis window.

9. The image processing system of claim 7, wherein the means for detecting determines the second constant region to be present whenever the value of the first pixel at the predetermined location equals the value of the second pixel at the predetermined location.

10. The image processing system of claim 7, wherein the means for detecting determines the constant region to be present whenever the value of the first pixel at the predetermined location equals the value of the second pixel at the predetermined location.

11. A device, comprising:

an image buffer that holds an image frame; and

an image processor that detects a current constant region of the image frame by shifting an image analysis window to a current position so that the image analysis window includes a new line of pixels from the image frame in comparison to a previous position of the image analysis window, wherein an entire area of the image analysis window at the previous position is a previous constant region of pixels and wherein a constant region is defined as a region wherein all pixels contained therein are substantially similar in value; and

the image processor determines whether an entire area of the image analysis window at the current position is the current constant region by analyzing a first pixel at a predetermined location in the image analysis window, wherein the analyzing comprises;

at a previous position of an image analysis window, determining whether the image analysis window contains a constant region;

should the determining result in a determination that the image analysis window contains a constant region, then the following process is performed;

determining if the first pixel has a value equal to a value of a second pixel at the predetermined location defined relative to the boundary of the image analysis window when the image analysis window was at the previous position,

if the value of the first pixel has a value equal to the value of the second pixel, then analyzing only the new line of pixels to determine if the current constant region is present.

12. The device of claim 11, wherein the predetermined location is a center of the image analysis window relative to the boundary of the image analysis window.

13. The device of claim 11, wherein the image processor detects the previous constant region at the previous position of the image analysis window.

14. The device of claim 11, wherein the image processor analyzes the new line of pixels by comparing a set of values of the new line of pixels to a value of the second pixel at the predetermined location when the image analysis window was at the previous position.

15. The device of claim 11, wherein the image processor shifts the image analysis window by shifting the image analysis window by one pixel.

16. A method for detecting a constant region of an image frame, comprising:

moving, with a processor, an image analysis window from a first position to a second position;

determining, with a processor, whether an entire area of the image analysis window containing a plurality of pixels at the second position is a constant region by analyzing, with a processor, less than all of the plurality of pixels in the image analysis window at the second position, wherein a constant region is defined as a region wherein all pixels contained therein are substantially similar in value.

17. The method of claim 16, wherein the determining comprises comparing the less than all of the plurality of pixels with a set of pixels that are similarly positioned in the image analysis window at the first position.

18. The method of claim 16, wherein the less than all of the plurality of pixels were not present within the image analysis window at the first position.

19. The method of claim 16, wherein the analyzing is performed only if a first predetermined pixel within the image analysis window at the first position has a value equal to a value of an identically positioned second predetermined pixel within the image analysis window at the second position.

20. A device, comprising:

an image buffer that holds an image frame; and

an image processor that detects a current constant region of the image frame by moving an image analysis window from a first position to a second position and determining whether an entire area of the image analysis window containing a plurality of pixels at the second position is a constant region by analyzing less than all of the plurality of pixels in the image analysis window at the second position, wherein a constant region is defined as a region wherein all pixels contained therein are substantially similar in value.

21. The device of claim 20, wherein the image processor compares the less than all of the plurality of pixels with a set of pixels that are similarly positioned in the image analysis window at the first position.

22. The device of claim 20, wherein the less than all of the plurality of pixels were not present within the image analysis window at the first position.

23. The device of claim 20, wherein the image processor performs the analyzing only if a first predetermined pixel within the image analysis window at the first position has a value equal to a value of an identically positioned second predetermined pixel within the image analysis window at the second position.