PULSE DETECTION FROM HEAD MOTIONS IN VIDEO

• US 20150005646A1
• Filed: 06/25/2014
• Published: 01/01/2015
• Est. Priority Date: 06/26/2013
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Balakrishnan, Guha, Guttag, John V., Durand, Frederic
• Granted Patent: US 10,638,942 B2
• Time in Patent Office: Days
• US Class Current: 600/479
• CPC Class Codes: A61B 5/004 adapted for image acquisition of a particular organ or body part A61B5/0082 takes precedence; arrangements for optical scanning A61B5/0062
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0255 Recording instruments specially adapted therefor
• CPC Class Codes: A61B 5/1128 using image analysis A61B5/1127 takes precedence

Abstract

Heart rates and beat lengths can be extracted from videos by measuring subtle head motion caused by the Newtonian reaction to the influx of blood at each beat. In an embodiment of the present invention, a method tracks features on the head and performs principal component analysis (PCA) to decompose their trajectories into a set of component motions. The method then selects a component that best corresponds to heartbeats based on its temporal frequency spectrum. Finally, the motion projected to this component is analyzed and peaks of the trajectories are identified, which correspond to heartbeats.

Claims

1. A method comprising:

selecting a region of a video;

tracking features of the selected region of the video; and

analyzing the features of the selected region of the video to determine an oscillation rate of a subject shown in the video.

2. The method of claim 1, wherein the oscillation rate is a heart rate or pulse rate of the subject.

3. The method of claim 1, further comprising extracting a component of the tracked features of the subject video.

4. The method of claim 3, wherein the extracted component is a vertical component, horizontal component, or vertical and horizontal components.

5. The method of claim 1, wherein selecting the region of the video includes finding a region of interest including a head of a subject.

6. The method of claim 1, wherein tracking the features includes:

determining a maximum distance traveled by each point between consecutive frames of the video; and

discarding features corresponding to points having a distance in consecutive frames of the video exceeding a mode of distribution.

7. The method of claim 1, wherein analyzing the features includes:

filtering the extracted features temporally;

generating a plurality of components using principal component analysis on the temporally filtered extracted features;

selecting one of the components of the plurality of components generated by the principal component analysis;

detecting peaks of the selected component; and

determining the oscillation rate based on the detected peaks of the selected component.

8. The method of claim 7, wherein filtering the extracted features temporally removes frequencies that are outside a predetermined range of pulse rates.

9. The method of claim 7, wherein performing principal component analysis includes decomposing the filtered features into a set of independent source signals.

10. The method of claim 7, wherein selecting the component includes selecting the component having a clearest main frequency.

11. A system comprising:

a selection module configured to select a region of a video;

a tracking module configured to track features of the selected region of the video; and

an analysis module the features of the selected region of the video to determine an oscillation rate of a subject shown in the video.

12. The system of claim 11, wherein the oscillation rate is a heart rate or pulse rate of the subject.

13. The system of claim 11, further comprising an extraction module configured to extract a component of the tracked features of the subject video.

14. The system of claim 13, wherein the extracted component is a vertical component, horizontal component, or vertical and horizontal component.

15. The system of claim 11, wherein the selection module is further configured to find a region of interest including a head of a subject.

16. The system of claim 11, wherein the tracking module is further configured to

determine a maximum distance traveled by each point between consecutive frames of the video;

and

discard features corresponding to points having a distance in consecutive frames of the video exceeding a mode of distribution.

17. The system of claim 11, wherein the analysis module is further configured to filter the extracted features temporally;

generate a plurality of components using principal component analysis on the temporally filtered extracted features;

select one of the components of the plurality of components generated by the principal component analysis;

detect peaks of the selected component; and

determine the oscillation rate based on the detected peaks of the selected component.

18. The system of claim 17, wherein the analysis module is further configured to filter the extracted features temporally by removing frequencies that are outside a predetermined range of pulse rates.

19. The system of claim 17, the analysis module is further configured to perform principal component analysis by decomposing the filtered features into a set of independent source signals.

20. The system of claim 17, wherein the analysis module is further configured to select the component by selecting the component having a clearest main frequency.