2. Action Units

What are Action Units?

Facial Action Coding System (FACS) is an anatomically based classification system for facial muscle movements. It examines the shape and appearance changes produced by the muscles of the face. Each muscle movement becomes an Action Unit (AU).

What do Action Units look like?

Note that not all AUs shown above are predicted by PyAFAR. More details can be found on `Output-Format` wiki page.

How are Action Units quantified?

AUs are measured along two dimensions.

1. Symmetry (Right, Left, Top, Bottom, Asymmetric)
2. Intensity (A, B, C, D, E)

Interested in learning more about Facial Action Coding System (FACS) for Action Unit annotation? Visit this interactive application