Crop operation focusing only on one face
Finds the most prominent face in the image and crops it to specified dimensions provided with the width and height parameters. If you however provide only one dimension, the other dimension will be chosen automatically to keep the aspect ratio of the face.
func=face
Sets margins around the face. You can set equal margins with face_margin=X or separate horizontal and vertical margins (face_margin=W,H).
face_margin=X|W,H