METHOD OF ANALYSING A VIDEO OF SPORTS MOTION

• US 20130178304A1
• Filed: 06/27/2012
• Published: 07/11/2013
• Est. Priority Date: 06/27/2011
• Status: Active Grant

• Current Assignee: Swing Profile Limited (Integrity Analysis Ltd.)
• Original Assignee: Swing Profile Limited (Integrity Analysis Ltd.)
• Inventors: Chan, Shun Heng
• Granted Patent: US 9,744,421 B2
• Time in Patent Office: Days
• US Class Current: 473/266
• CPC Class Codes: A63B 69/36 for golf
• CPC Class Codes: G06T 2207/30221 Sports video; Sports image
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06V 20/42 of sport video content
• CPC Class Codes: G06V 20/47 Detecting features for summarising video content
• CPC Class Codes: G06V 40/23 Recognition of whole body movements, e.g. for sport training

Abstract

The invention is directed to a method, apparatus, system and computer program product for analysing video images of a sports motion and, in particular, to identification of key motion positions within a video and automatic extraction of segments of a video containing a sports motion. Video data displaying a sports motion comprises data representative of a number of image frames. For a number of image frames, one or more frame difference measures are calculated between the image frame and another image frame. The frame difference measures are analysed to identify a plurality of image frames that each show a key position of the sports motion. The segment of the video containing the sports motion showing the sports motion is between two of the image frames showing the key positions. Frame difference measures may be calculated based on pixel difference measures or optical flow techniques.

Claims

1. A method of analysing a video, at least a portion of the video displaying a person performing a sports motion, the method comprising:

receiving data representative of a number T of image frames constituting the video;

calculating, for each of a number T_C of the image frames, one or more frame difference measures between the image frame and another image frame;

analysing the frame difference measures to identify a plurality of image frames that each show a key position of the person while performing the sports motion displayed in the video.

2. The method as claimed in claim 1, further comprising:

identifying the portion of the video displaying the person while performing the sports motion.

4. The method as claimed in claim 1 further comprising:

identifying one or more motion phases of the sports motion from the frame difference measures.

6. The method as claimed in claim 1, wherein the one or more frame difference measures comprise one or more of the following:

a measure of the amount of movement between image frames;

a measure of the position of movement between image frames; and

a measure of the velocity or a derivative thereof of movement between image frames.

9. The method as claimed in claim 1, wherein each image frame comprises a number P of pixels or groups of pixels and the method further comprises:

for each of the number T_C of the image frames, comparing each of a number P_C of pixels or groups of pixels with corresponding pixels or groups of pixels in the other image frame and calculating one or more pixel difference measures.

11. The method as claimed in claim 9, further comprising:

calculating the one or more frame difference measures based on the one or more pixel difference measures.

14. The method as claimed in claim 9, wherein the pixel difference measures comprise one or more of the following:

a measure of the amount of pixel movement between image frames;

a measure of the position of pixel movement between image frames; and

a measure of the velocity or a derivative thereof of pixel movement between image frames.

16. The method as claimed in claim 1, wherein the method comprises:

further comprising;

for each of the number T_C of the image frames, determining optical flow between the pixels or groups of pixels and the corresponding pixels or groups of pixels in the other image frame.

17. The method as claimed in claim 16, wherein the determining optical flow comprises determining local correlations between pixels or groups of pixels between each image frame and the other image frame.

18. The method as claimed in claim 1, wherein the analysing the frame difference measures to identify a plurality of image frames that each show a key position of the person while performing the sports motion comprises:

identifying a plurality of patterns in temporal variations in frame difference measures; and

associating each pattern with one of the motion phases of the sports motion.

19. The method as claimed in claim 18, wherein the identifying a plurality of patterns comprises identifying peaks and/or troughs in the temporal variations in frame difference measures.

20. The method as claimed in claim 18, wherein the identifying a plurality of patterns comprises identifying peaks and/or troughs in vertical pixel movements between image frames.

21. The method as claimed in claim 1, further comprising:

using a decision model to analyse the frame difference measures to identify a plurality of image frames that each show a key position of the person while performing the sports motion.

24. The method as claimed in claim 17, further comprising:

applying an image stabilisation algorithm comprising computing optical flow vectors and subsequently using the optical flow vectors to calculate the frame difference measures.

40. The method as claimed in claim 1 further comprising:

identifying an object displayed in one or more of the image frames.

43. The method as claimed in claim 40 further comprising:

constructing one or more lines and displaying the line(s) on one or more of the image frames.

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44. (canceled)

45. An apparatus for analysing a video, at least a portion of the video displaying a person performing a sports motion, the apparatus comprising:

a memory configured to store data representative of a number T of image frames;

a processor configured to calculate, for each of a number T_C of the image frames, one or more frame difference measures between the image frame and another image frame, the processor being further configured to;

analyse the frame difference measures to identify a plurality of image frames that each show a key position of the person while performing the sports motion displayed in the video.

46. The apparatus as claimed in claim 45, further comprising:

a video capture device for recording the video.

47. The apparatus as claimed in claim 45 further comprising:

a display screen for displaying the identified image frames that each show a key position.

48-49. -49. (canceled)

50. A computer program product which, when executed by a computer, causes the computer to perform a method comprising the steps of:

receiving data representative of a number T of image frames, the image frames comprising at least a portion of a video displaying a person performing a sports motion;

calculating, for each of a number T_C of the image frames, one or more frame difference measures between the image frame and another image frame;

analysing the frame difference measures to identify a plurality of image frames that each show a key position of the person while performing the sports motion displayed in the video.