Method and apparatus for detecting image movement

• US 20060139458A1
• Filed: 08/04/2005
• Published: 06/29/2006
• Est. Priority Date: 12/27/2004
• Status: Active Grant

• Current Assignee: Sunplus Technology Co., Ltd
• Original Assignee: Sunplus Technology Co., Ltd
• Inventors: Chou, Tse-An
• Granted Patent: US 7,796,120 B2
• Time in Patent Office: Days
• US Class Current: 348/208.100
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

A method of detecting image movement is provided. A reference frame is accessed, and a reference window is captured from the reference frame. A sampling frame is then accessed. When the reference window has not reached the margin of the reference frame, a new window is captured from the reference frame to replace the reference window. From the reference frame, a window matching the reference window is searched and a moving vector is calculated. When the sampling window reaches the margin of the sampling frame, the sampling frame replaces the reference frame. Another reference window is also captured from the reference frame, and the step of accessing the sampling frame is repeated.

Claims

1. A method of detecting image movement, comprising the following steps:

(A) accessing a reference frame, and capturing a reference window from the reference frame;

(B) accessing a sampling frame;

(C) capturing a new window to replace the reference window, if the reference window has not reached a margin of the reference frame;

(D) searching a sampling window matching the reference window, and calculating a moving vector based on the reference window in the sampling frame;

(E) replacing the reference frame with the sampling frame, and capturing the reference window in the reference frame, if the sampling window has reached a margin of the sampling frame; and

(F) repeating the step (B).

2. The method of detecting image movement of claim 1, wherein in step (C), the new window is captured in the reference frame according to the moving vector or a relative speed corresponding to the moving vector.

3. The method of detecting image movement of claim 1, wherein in step (C), the new window is captured in a direction reverse to a moving direction of the sampling window.

4. The method of detecting image movement of claim 1, wherein in step (D), the sampling window is searched by looking for a window having a size similar to the reference window and whose gray level is most similar to that of the reference window in the reference frame.

5. The method of detecting image movement of claim 1, further comprising a method of compensating the image movement between the steps (D) and (E), the method of compensating the image movement comprising the following steps:

(a) determining whether a pre-determined moving vector is exceeded according to an acceleration;

(b) outputting a predicted moving vector, if the pre-determined moving vector is exceeded; and

(c) if the pre-determined moving vector is not exceeded, determining whether the acceleration reaches a pre-determined count in an allowable range, and if the acceleration reaches the pre-determined count in the allowable range, predicting a next moving vector and outputting this displacement;

if not, only outputting the displacement.

6. The method of detecting image movement of claim 5, wherein the pre-determined count in the allowable range in the step (c) is a detected acceleration of less than 1 pixel/sec² for at least three consecutive times.

7. An apparatus for detecting image movement, comprising:

an optical-sensing unit to access a frame;

an auxiliary-calculating unit to calculate and search a matching frame;

a micro-processing unit coupled to the auxiliary-calculating unit, the micro-processing unit accessing a reference frame through the optical-sensing unit, and capturing a reference window in the reference window, the micro-processing unit also accessing a sampling frame, the micro-processing unit searching a sampling window matching the reference window, and calculating a moving vector based on the reference window in the sampling frame, and if the reference window has not reached a margin of the reference frame, a new window being captured to replace the reference window;

if the reference window has reached a margin of the reference frame, and the sampling window has reached a margin of the sampling frame, the reference frame being replaced with the sampling frame, and the reference window being captured in the reference frame.

8. The apparatus for detecting image movement of claim 7, wherein the apparatus comprises at least one analog/digital signal conversion unit and a signal filter unit, wherein the optical-sensing unit is coupled to the analog/digital signal conversion unit, and the analog/digital signal conversion unit is coupled to the signal filter unit.

9. The apparatus for detecting image movement of claim 7, wherein the new window is captured from the reference frame according to the moving vector or a relative speed corresponding to the moving vector.

10. The apparatus for detecting image movement of claim 7, wherein the new window is captured in a direction reverse to a moving direction of the sampling window.

11. The apparatus for detecting image movement of claim 7, wherein the sampling window is searched by looking for a window having a size similar to the reference window and whose gray level is most similar to that of the reference window in the reference frame.

12. The apparatus for detecting image movement of claim 7, further comprising compensating the image movement after the micro-processing unit calculates the moving vector, the step of compensating the image movement comprising the following steps:

(a) determining whether a pre-determined moving vector is exceeded according to an acceleration;

(b) outputting a predicted moving vector, if the pre-determined moving vector is exceeded; and

(c) if the pre-determined moving vector is not exceeded, determining whether the acceleration reaches a pre-determined count in an allowable range;

if the acceleration reaches the pre-determined count in the allowable range, predicting a next moving vector and outputting this displacement;

if not, only outputting the displacement.

13. The apparatus for detecting image movement of claim 7, wherein the apparatus for detecting image movement is an optical mouse.

14. The apparatus for detecting image movement of claim 13, wherein the pre-determined count in the allowable range is a detected acceleration of less than 1 pixel/sec² for at least three consecutive times.

15. A method of compensating image movement, comprising the following steps:

(A) accessing a reference frame, and capturing a reference window from the reference frame;

(B) accessing a sampling frame;

(C) searching a sampling window matching the reference window, and calculating a moving vector based on the reference window in the sampling frame;

(D) determining whether a pre-determined moving vector is exceeded according to an acceleration;

(E) outputting a predicted moving vector, if the predetermined moving vector is exceeded;

(F) if the pre-determined moving vector is not exceeded, determining whether the acceleration reaches a pre-determined count in an allowable range;

if the acceleration reaches the pre-determined count in the allowable range, predicting a next moving vector and outputting this displacement;

if not, only outputting the displacement; and

(G) repeating the step (B).

16. The method of compensating image movement of claim 15, wherein the pre-determined count in the allowable range in the step (F) is a detected acceleration of less than 1 pixel/sec² for at least three consecutive times.

17. The method of compensating image movement of claim 15, wherein in step (E), whether to reset a counting value of the acceleration in the allowable range is determined.

18. An apparatus for compensating image movement, comprising:

an optical-sensing unit to access a frame;

an auxiliary-calculating unit to calculate and search a matching frame;

a micro-processing unit coupled to the auxiliary-calculating unit, the micro-processing unit accessing a reference frame through the optical-sensing unit, and capturing a reference window in the reference window, the micro-processing unit also accessing a sampling frame, the micro-processing unit searching a sampling window matching the reference window, and calculating a moving vector based on the reference window in the sampling frame, the micro-processing unit determining whether a pre-determined moving vector is exceeded according to an acceleration;

if the pre-determined moving vector is exceeded, the micro-processing unit outputting a predicted moving vector;

if the pre-determined moving vector is not exceeded, the micro-processing unit determining whether the acceleration reaches a pre-determined count in an allowable range;

if the acceleration reaches the pre-determined count in the allowable range, predicting a next moving vector and outputting the displacement, and then the reference frame being replaced by the sampling frame and the reference window being captured from the reference frame.

19. The apparatus for compensating image movement of claim 18, wherein when the pre-determined moving vector is exceeded, the micro-processing unit further determines whether to reset a counting value of the acceleration in the allowable range.

20. The apparatus for compensating image movement of claim 19, wherein the micro-processing unit determines whether the acceleration is in the allowable range when the pre-determined count in the allowable range is a detected acceleration of less than 1 pixel/sec² for at least three consecutive times.