Fig. 9

Heatmaps of how the various motion artifacts impact the handcrafted metrics extracted from the green PPG signal ((a) left ear; (b) right ear). The values reported in the heatmaps are the Mean Absolute Error (MAE) with respect to the still baseline. The heatmaps’ cells are annotated with a T whenever there is a statistically significant difference between the still baseline signal and the MA-corrupted one (p < 0.05).