How to filter this signal to get a heartbeat signal?

I am giving my first steps in data analysis, gathering/cleaning.

To learn, I am trying to create a simple code that can detect heartbeats from color variations from the image coming from the camera on the iPhone.

This is what I have done so far:

I have created a code that detects faces and cuts them from the image.

then I get the average color from that face image.

Because the values are grabbed at irregular time intervals, I interpolate the data. Now I have a series of values "taken" at regular intervals.

Plotting the data I have this:

enter image description here

I think I am seeing something that looks like heartbeats there.

To confirm that I am not seeing artifacts from the camera, I sample a rectangle from the background and I get the same color with very little random variation. The background color is stable and shows barely any variation.

Now, I apply a Direct Cosine Transform to the data and get this:

enter image description here

The DCT has negative vales.

The two first items of the DCT are peaks, at t=0 and t=0.10482311 seconds.

I read a paper where the researcher says heartbeats occur between 0.4 and 4Hz. I suppose this has a relation why the first two DCT items are peaks...

What do I do now?

I have tried to apply a threshold to zero every term from the DCT below 150 and do an inverse DCT to reconstruct the signal and got this

enter image description here

I have reduced the threshold to 85 and got this

enter image description here

I am not sure if I see a heartbeat there. I mean, the peaks where the beats start.

This is the data at regular time intervals I have (256 samples):

and these are the regular time intervals

edited 14 hours ago

asked 14 hours ago

SpaceDog

1112

New contributor

add a comment |

I am giving my first steps in data analysis, gathering/cleaning.

To learn, I am trying to create a simple code that can detect heartbeats from color variations from the image coming from the camera on the iPhone.

This is what I have done so far:

I have created a code that detects faces and cuts them from the image.

then I get the average color from that face image.

Because the values are grabbed at irregular time intervals, I interpolate the data. Now I have a series of values "taken" at regular intervals.

Plotting the data I have this:

enter image description here

I think I am seeing something that looks like heartbeats there.

Now, I apply a Direct Cosine Transform to the data and get this:

enter image description here

The DCT has negative vales.

The two first items of the DCT are peaks, at t=0 and t=0.10482311 seconds.

I read a paper where the researcher says heartbeats occur between 0.4 and 4Hz. I suppose this has a relation why the first two DCT items are peaks...

What do I do now?

I have tried to apply a threshold to zero every term from the DCT below 150 and do an inverse DCT to reconstruct the signal and got this

enter image description here

I have reduced the threshold to 85 and got this

enter image description here

I am not sure if I see a heartbeat there. I mean, the peaks where the beats start.

This is the data at regular time intervals I have (256 samples):

and these are the regular time intervals

edited 14 hours ago

asked 14 hours ago

SpaceDog

1112

New contributor

add a comment |

I am giving my first steps in data analysis, gathering/cleaning.

To learn, I am trying to create a simple code that can detect heartbeats from color variations from the image coming from the camera on the iPhone.

This is what I have done so far:

I have created a code that detects faces and cuts them from the image.

then I get the average color from that face image.

Because the values are grabbed at irregular time intervals, I interpolate the data. Now I have a series of values "taken" at regular intervals.

Plotting the data I have this:

enter image description here

I think I am seeing something that looks like heartbeats there.

Now, I apply a Direct Cosine Transform to the data and get this:

enter image description here

The DCT has negative vales.

The two first items of the DCT are peaks, at t=0 and t=0.10482311 seconds.

I read a paper where the researcher says heartbeats occur between 0.4 and 4Hz. I suppose this has a relation why the first two DCT items are peaks...

What do I do now?

I have tried to apply a threshold to zero every term from the DCT below 150 and do an inverse DCT to reconstruct the signal and got this

enter image description here

I have reduced the threshold to 85 and got this

enter image description here

I am not sure if I see a heartbeat there. I mean, the peaks where the beats start.

This is the data at regular time intervals I have (256 samples):

and these are the regular time intervals

edited 14 hours ago

asked 14 hours ago

SpaceDog

1112

New contributor

I am giving my first steps in data analysis, gathering/cleaning.

To learn, I am trying to create a simple code that can detect heartbeats from color variations from the image coming from the camera on the iPhone.

This is what I have done so far:

I have created a code that detects faces and cuts them from the image.

then I get the average color from that face image.

Because the values are grabbed at irregular time intervals, I interpolate the data. Now I have a series of values "taken" at regular intervals.

Plotting the data I have this:

enter image description here

I think I am seeing something that looks like heartbeats there.

Now, I apply a Direct Cosine Transform to the data and get this:

enter image description here

The DCT has negative vales.

The two first items of the DCT are peaks, at t=0 and t=0.10482311 seconds.

I read a paper where the researcher says heartbeats occur between 0.4 and 4Hz. I suppose this has a relation why the first two DCT items are peaks...

What do I do now?

I have tried to apply a threshold to zero every term from the DCT below 150 and do an inverse DCT to reconstruct the signal and got this

enter image description here

I have reduced the threshold to 85 and got this

enter image description here

I am not sure if I see a heartbeat there. I mean, the peaks where the beats start.

This is the data at regular time intervals I have (256 samples):

and these are the regular time intervals

data-mining dataset data-cleaning

edited 14 hours ago

asked 14 hours ago

SpaceDog

1112

New contributor

edited 14 hours ago

asked 14 hours ago

SpaceDog

1112

New contributor

edited 14 hours ago

asked 14 hours ago

SpaceDog

1112

New contributor

asked 14 hours ago

SpaceDog

1112

asked 14 hours ago

SpaceDog

1112

New contributor

SpaceDog is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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