Method and system for heart rate extraction from RGB images

1 . A method for determining one or more heart beat features, the method comprising:

capturing a series of images of a user in a car by a camera in the car, wherein each image comprises one or more colour signals;

for each of the images:

locating a face of the user in the image;

determining a boundary in the image, wherein the face is located within the boundary;

detecting one or more facial features within the boundary; and

based on the detected facial features, determining one or more regions in the image representing skin patches in the face;

analysing the colour signals in the regions representing the skin patches; and

determining one or more heart beat features based on the analysis;

wherein analysing the colour signals further comprises:

determining colour changes in the series of images of one or more skin patches;

creating a pulse wave for each skin patch based on the colour changes;

splitting the pulse waves from each skin patch into a plurality of overlapping time windows, wherein each of the plurality of overlapping time windows overlaps in time with an adjacent time window of the plurality of time windows;

transforming each of the windows into the frequency space to generate frequency spectra;

summing up said spectra into one accumulated spectrum;

comparing each frequency spectrum with a predetermined pulse wave pattern and determining a level of similarity;

discarding all pulse waves for which the level of similarity does not reach a first predetermined threshold; and

determining a weighted average of all pulse waves for which the level of similarity does reach the first predetermined threshold, wherein the level of similarity defines weights for the weighted average.

2 . The method of claim 1 , wherein capturing a series of images is performed using a visual light camera capturing RGB images.

3 . The method of claim 1 , further comprising determining blood flow intensities based on the colour changes.

4 . The method of claim 1 , further comprising detecting a noise level of each weight-averaged spectrum; and summing up all pulse waves for which the noise level does not exceed a predetermined threshold to an accumulated pulse wave.

5 . The method of claim 1 , further comprising processing the pulse wave to extract heart rate features, wherein the heart rate features comprise one or more of heart rate, inter-beat intervals and heart rate variability.

6 . A system for determining one or more heart beat features, the system comprising:

a camera; and

a computing device;

wherein the system is configured to execute the method of claim 1 .

7 . The system of claim 6 , wherein the camera is a visible light camera capturing RGB images.

8 . The method of claim 4 , further comprising discarding all pulse waves for which the noise level exceeds a second predetermined threshold.