Efficient detection of constant regions of an image

1. An image processor that is configured to:

determine that an entire area of an image analysis window at a previous position of an image frame is a constant region; and

in response to determining that the entire area of the image analysis window at the previous position is a constant region,

analyze, at a current position of the image frame, a number of pixels in the image analysis window that is less than a total number of pixels in the image analysis window; and

determine that an entire area of the image analysis window at the current position is a constant region based on the analysis of the number of pixels in the image analysis window that is less than the total number of pixels at the current position.

2. The image processor of claim 1 , wherein the image processor is further configured to shift the image analysis window from the previous position to the current position so that the image analysis window at the current position includes a new line of pixels from the image frame that is different from any line of pixels in the image analysis window at the previous position; and

wherein the analysis of the number of pixels in the image analysis window that is less than the total number of pixels at the current position comprises an analysis of a pixel in the new line of pixels.

3. The image processor of claim 2 , wherein the image processor is configured to analyze a number of pixels in the image analysis window that is less than the total number of pixels in the image analysis window at the current position by being configured to:

determine that a value of a first pixel in the image analysis window at the current position is equal to a value of a second pixel in the image analysis window at the previous position, wherein the first pixel and the second pixel are located at a predetermined location, the predetermined location being relative to a boundary of the image analysis window; and

analyze only the new line of pixels after determining that the value of the first pixel is equal to the value of the second pixel.

4. The image processor of claim 3 , wherein the predetermined location is a center of the image analysis window relative to the boundary of the image analysis window.

5. The image processor of claim 3 , wherein the image processor is configured to analyze only 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.

6. The image processor of claim 3 , wherein the image processor is configured to shift the image analysis window one pixel.

7. The image processor of claim 1 , wherein the image processor is further configured to detect a current constant region of an image frame by analyzing all of the pixels in the image analysis window;

wherein the image processor is configured to analyze all of the pixels in the image analysis window when a value of a first pixel in the area of the image analysis window in the current position is not equal to a value of a second pixel in the area of the image analysis window in the previous position;

wherein the first pixel and the second pixel are located at a predetermined location; and

wherein the predetermined location is relative to a boundary of the image analysis window.

8. The image processor of claim 1 , wherein the image processor is configured to determine that an entire area of the image analysis window at the current position is a constant region by determining that all of the pixels in the image analysis window are substantially similar in value.

9. An image processor that is configured to:

determine that a first region of pixels from an image frame in an image analysis window at a first position is a constant region of pixels;

shift the image analysis window from the first position to a second position, wherein a second region in the image analysis window at the second position comprises a new line of pixels from the image frame that is different from any line of pixels in the image analysis window at the first position; and

detect that the second region of the image analysis window at the second position is a constant region by analyzing a number of pixels in the second region that is less than a total number of pixels in the second region.

10. The image processor of claim 9 , wherein the analysis of the number of pixels in the second region that is less than the total number of pixels in the second region comprises:

a determination that a value of a first pixel in the second region is equal to a value of a second pixel in the first region, wherein the first pixel and the second pixel are located at a predetermined location, and wherein the predetermined location is relative to a boundary of the image analysis window; and

an analysis of only the new line of pixels after determining that the value of the first pixel is equal to the value of the second pixel.

11. The image processor of claim 10 , wherein the image processor is configured to analyze only 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 first position.

12. The image processor of claim 10 , wherein the predetermined location is a center of the image analysis window relative to the boundary of the image analysis window.

13. The image processor of claim 9 , wherein the image processor is configured to shift the image analysis window one pixel.

14. The image processor of claim 9 , wherein the image processor is further configured to detect a current constant region of an image frame by analyzing all of the pixels in the image analysis window;

wherein the image processor is configured to analyze all of the pixels in the image analysis window when a value of a first pixel in the area of the image analysis window in the current position is not equal to a value of a second pixel in the area of the image analysis window in the previous position;

wherein the first pixel and the second pixel are located at a predetermined location; and

wherein the predetermined location is relative to a boundary of the image analysis window.

15. The image processor of claim 9 , wherein the image processor is configured to determine that an entire area of the image analysis window at the current position is a constant region by determining that all of the pixels in the image analysis window are substantially similar in value.

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

determining that an entire area of an image analysis window at a previous position of an image frame is a constant region;

in response to determining that the entire area of the image analysis window at the previous position is a constant region:

analyzing, at a current position of the image frame, a number of pixels in the image analysis window that is less than a total number of pixels in the image analysis window; and

determining that an entire area of the image analysis window at the current position is a constant region based on the analysis of the number of pixels in the image analysis window that is less than the total number of pixels at the current position.

17. The method of claim 16 , further comprising shifting the image analysis window from the previous position to the current position so that the image analysis window at the current position includes a new line of pixels from the image frame that is different from any line of pixels in the image analysis window at the previous position; and

wherein analyzing the number of pixels in the image analysis window that is less than the total number of pixels at the current position comprises analyzing a pixel in the new line of pixels.

18. The method of claim 17 , wherein analyzing a number of pixels in the image analysis window that is less than the total number of pixels in the image analysis window at the current position comprises:

determining that a value of a first pixel in the image analysis window at the current position is equal to a value of a second pixel in the image analysis window at the previous position, wherein the first pixel and the second pixel are located at a predetermined location, the predetermined location being relative to a boundary of the image analysis window; and

analyzing only the new line of pixels after determining that the value of the first pixel is equal to the value of the second pixel.

19. The method of claim 16 , further comprising detecting a current constant region of an image frame by analyzing all of the pixels in the image analysis window;

wherein analyzing all of the pixels in the image analysis window is performed when a value of a first pixel in the area of the image analysis window in the current position is not equal to a value of a second pixel in the area of the image analysis window in the previous position;

wherein the first pixel and the second pixel are located at a predetermined location; and

wherein the predetermined location is relative to a boundary of the image analysis window.

20. The method of claim 16 , wherein determining that an entire area of the image analysis window at the current position is a constant region comprises determining that all of the pixels in the image analysis window are substantially similar in value.