Composite portraiture (also known as composite photographs) is a technique invented by Sir

Francis Galton Sir Francis Galton, FRS FRAI (; 16 February 1822 – 17 January 1911), was an English Victorian era polymath: a statistician, sociologist, psychologist, Anthropology, anthropologist, tropical Exploration, explorer, geographer, Inventio ...

in the 1880s after a suggestion by

Herbert Spencer Herbert Spencer (27 April 1820 – 8 December 1903) was an English philosopher, psychologist, biologist, anthropologist, and sociologist famous for his hypothesis of social Darwinism. Spencer originated the expression " survival of the f ...

for registering photographs of human faces on the two eyes to create an "average" photograph of all those in the photographed group. Spencer had suggested using onion paper and line drawings, but Galton devised a technique for multiple exposures on the same photographic plate. He noticed that these composite portraits were more attractive than any individual member, and this has generated a large body of research on human attractiveness and

averageness In physical attractiveness studies, averageness describes the physical beauty that results from averaging the facial features of people of the same gender and approximately the same age.Langlois, J.H., Musselman, L. (1995). The myths and mysteries ...

one hundred years later. He also suggested in a

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

presentation in 1883 that the composites provided an interesting concrete representation of human

ideal type Ideal type (german: Idealtypus), also known as pure type, is a typological term most closely associated with sociologist Max Weber (1864–1920). For Weber, the conduct of social science depends upon the construction of abstract, hypothetical con ...

s and

concept Concepts are defined as abstract ideas. They are understood to be the fundamental building blocks of the concept behind principles, thoughts and beliefs. They play an important role in all aspects of cognition. As such, concepts are studied by ...

s. He discussed using the technique to investigate characteristics of common types of humanity, such as criminals. In his mind, it was an extension of the statistical techniques of

average In ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of the numbers divided by how many numbers are in the list (the arithmetic mean). For example, the average of the numbers 2, 3, 4, 7 ...

s and

correlation In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistic ...

. In this sense, it represents one of the first implementations of

convolution In mathematics (in particular, functional analysis), convolution is a mathematical operation on two functions ( and ) that produces a third function (f*g) that expresses how the shape of one is modified by the other. The term ''convolution'' ...

factor analysis Factor analysis is a statistical method used to describe variability among observed, correlated variables in terms of a potentially lower number of unobserved variables called factors. For example, it is possible that variations in six observed ...

and

neural network A neural network is a network or circuit of biological neurons, or, in a modern sense, an artificial neural network, composed of artificial neurons or nodes. Thus, a neural network is either a biological neural network, made up of biological ...

s in the understanding of

knowledge representation Knowledge representation and reasoning (KRR, KR&R, KR²) is the field of artificial intelligence (AI) dedicated to representing information about the world in a form that a computer system can use to solve complex tasks such as diagnosing a medic ...

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 Sir Francis Galton, FRS FRAI (; 16 February 1822 – 17 January 1911), was an English Victorian era polymath: a statistician, sociologist, psychologist, anthropologist, tropical explorer, geographer, inventor, meteorologist, prot ...

attempted to define

physiognomic Physiognomy (from the Greek , , meaning "nature", and , meaning "judge" or "interpreter") is the practice of assessing a person's character or personality from their outer appearance—especially the face. The term can also refer to the general ...

characteristics of health, disease, beauty, and criminality, via a method of composite photography. Galton's process involved the photographic superimposition of two or more faces by multiple exposures. After averaging together photographs of violent criminals, he found that the composite appeared "more respectable" than any of the faces comprising it; this was likely due to the irregularities of the skin across the constituent images being averaged out in the final blend. Since the advancement of computer graphics technology in the early 1990s, Galton's composite technique has been adopted and greatly improved using computer graphics software.Yamaguchi, M. K., Hirukawa, T., & Kanazawa, S. (1995)
Judgment of gender through facial parts.
{{Webarchive, url=https://web.archive.org/web/20130512135158/http://www.perceptionweb.com/abstract.cgi?id=p240563 , date=2013-05-12 ''Perception, 24'', 563–575.

References

External links

Samples of Galton's composites
Portrait art Knowledge representation