The facial composite image procedure.

The idea of creating an averaged face dates back to the works of Galton (1878) who succeeded in photographically blending different faces by multiple exposures. The pupils of the eyes were used as stable points for the blending procedure. Employing a similar technique for averaging, Langlois and Roggman (1990) demonstrated the computer production of facial prototypes. In order to produce a face prototype all individual facial images depicting the same emotional expressions need to be averaged in terms of their corresponding pixels. Averaged faces emerge when using the eye pupils as approximate reference points for each facial image. However, the resulting facial expressions are rather blurred and at times confusing as to the manifest Actions Units. This is due to the different physiognomical characteristics of the subjects' faces. With the exception of the pupils that are uniformly defined as points in each face all other AUs lose the sharpness of their contours and consequently the poignancy of their appearance. With a few exceptions a reliable FACS coding is not possible. It is evident that the averaging procedure based on only two points of the image (the center of the pupils) results in blurred facial composite images where the facial expression is not adequately depicted.