DanioScope calculates heart rate by analyzing changes in the selected heart area of a video. Occasionally, this may result in an unrealistically low heart rate. This typically happens when:
Low contrast can hide the true heartbeat signal, allowing noise or irregular blood movement to dominate the analysis.
In the plot above, random peaks of high amplitude (due to noise or blood flow) mask the regular but lower true heartbeat signal. Zooming in can help identify which are the actual beats. DanioScope mistakenly selects the highest peak (around 15 BPM) from the power spectrum:
This leads DanioScope to incorrectly report a heart rate of 15 BPM.
Example of a well-defined heart area:
Now the correct peak (~180 BPM) is dominant in the power spectrum:
DanioScope now reports a heart rate of 183 BPM.
Zoom into the activity plot to verify that there are approximately 3 clear peaks per second, confirming the 180 BPM result: