Composite portrait

[1][2] Spencer had suggested using onion paper and line drawings, but Galton devised a technique for multiple exposures on the same photographic plate.

He also suggested in a Royal Society presentation in 1883 that the composites provided an interesting concrete representation of human ideal types and concepts.

In this sense, it represents one of the first implementations of convolution factor analysis and neural networks in the understanding of knowledge representation in the human mind.

Galton also suggested that the technique could be used for creating natural types of common objects.

During the late 19th century, English psychometrician Sir Francis Galton attempted to define physiognomic characteristics of health, disease, beauty, and criminality, via a method of composite photography.