What is the range in the size of the face in the still images?
What is important is not the absolute size of the face, but rather the ratio of the size of the image to the size of the face. For still images, the size of the face will be measured in the number of pixels between the centers of the eyes. For calculations to this answer, the size of the image will be measured by the smaller of the two dimensions. For controlled still images, the largest faces could have a size ratio of 2.0, and the smallest could have a size ratio of 10.0. For uncontrolled still images, the largest faces could have a size ratio of 4.0, and the smallest could have a size ratio of 20.0.
