Matrix Mirrors is a photographic project that uses portraits and mathematical analysis to study concepts of human identity and recognition. Facial images were collected and analyzed to extract underlying "components" that can be used to rapidly reconstruct portraits. Experiments showed these components can reconstruct faces across gender and ethnicity. Statistical analysis found averages of small mixed groups were nearly indistinguishable from totals, suggesting human faces share more similarities than differences. The results indicate the potential for a single image to represent humanity.

1. "The human face is indeed, like the face of God of some Oriental theogony, a whole cluster of
faces, crowded together but on different planes so that one does not see them all at once"
Marcel Proust. 1919
This document intends to be a very high level description of the concept behind Matrix Mirrors
photographic project, keeping in mind the objective of not to go beyond 2 pages. It describes the process
used and introduces some of the project’s most innovating and eventually most interesting conclusions,
without getting into mathematical details and not describing the methods and the tools used to achieve
the project’s results.
See images in http://www.renatoroque.com/EspelhosMatriciais/index.htm
Matrix Mirrors is a photographic project on human identity and about the way identity is associated with
the image of the human face, namely trough the use of photography. Natural and artificial mirrors were
the first artifacts capable of reproducing the human face. Photography - a mirror with memory, the way
the photography process was described by Daguerre when it was invented - allowed an easy and durable
representation of the human face. Matrix Mirrors has a close relationship with the history of Photography
and the way photography has been used, nearly from its beginning, more than 150 years ago, to identify a
person, using face portraits. In a way Matrix Mirrors makes use of special mirrors (matrix mirrors),
constructed as matrix of numbers, matrixes which reflect the essential information contained in the human
faces. How do we recognize a friend, how does he recognize us? What difference is there between my face
and my neighbors’ face? What difference exists between a man and a woman’s face? Between an
European and an African? What new information can I find in a new face of someone whom I have never
seen before? How can I make use of it? All these are questions which Matrix Mirrors tries to address, trying
to reach the essence of photography and using a set of mathematical and scientific tools to work the image
information.
Since the beginning of Humanity the human face has been the most recognizable mark to identify a person.
Humans believe that we all look very different and therefore we are all easy to recognize. Even in our days,
although other more reliable methods of identification have been developed, such as fingerprints or DNA,
the image of the face remains as the everyday’s way to identify friends or acquainted, and the face portrait
remains as an essential part of every ID. These facts are related with the very complex and sophisticated
mechanisms that humans developed, creating specialized areas in the brain (just for faces), to get a quick
and very efficient identification, based on a human face image. It is easy to understand the importance
that such sophisticated mechanisms must have had for the human specie survival: the efficiency of those
mechanisms might signify in many situations escaping from death.
Because of the importance the face image plays in human culture, it is not surprising that it has been a
main subject for art, in particular painting and sculpture. Painting and sculpture have for centuries played
the role of registering the human face, eventually with the illusion of achieving eternity for the portrayed.
But painting and sculpture were reserved for kings, for popes and nobles. Photography introduced a huge
change. Photography made it not only possible but very easy to register everyone’s face. The simplification
and popularity of the photographic process turned photography into the best and the accepted process to
produce the images of faces, and therefore produce images to be the basis of the identification process.
Therefore photography was quickly accepted as the way to obtain portraits used for identification.
Photography was easy, cheap and appeared to be much more reliable and objective. Documents such as
IDs or passports had a simple way of getting an image which could be used for a quick, simple and efficient
identification.
Because photography quickly replaced painting in human representation, it will be not a surprise that
human portrait is an important part of Photography’s history, since its beginning in the middle of the XIXth

2. century. But when we refer to Photography’s history we should not only address the well known portraits
from pioneer photographers like Nadar or Julia Margaret Cameron and portraits made by most of the best
known photographers ever, from all over the world, but as well a darker side of Photography’s history,
related with the authority of the state, police files and even essays to use photography as a support for
oppression and even racist theories.
In Matrix Mirrors project 439 portraits were made in Oporto University: students, teachers and staff from
the University, men and women, from 18 up 65 years old. These face portraits were used to construct a
face database with 400 faces – the other 39 were put apart for tests - and a set of mathematical and image
processing tools were used to obtain essential sets of information from all those portraits. These essential
information elements, which could be seen as information which is an important part of all portraits, are
called components. Curiously these components, calculated using those mathematical tools, represented
as photographs, look like abstract faces.
What is more relevant is that adding those components in the right percentage, all portraits can be very
rapidly constructed. Actually only about 20 to 30 components are necessary to get a portrait which is
recognizable by most people. Questionnaires were used and their results were analyzed using scientific
tools to prove it. In reality, the components calculated in Matrix Mirrors, using different techniques,
proved to be able to construct very rapidly not only portraits from inside the database, but as well portraits
from someone else. Curiously the experiments indicate clearly that women faces can be reconstructed
from men and the opposite is also true, and it was discovered that for example an African face can be
reconstructed adding up components which were calculated using a database of what we might call, by
simplification, "white people". All these results indicate that, against perhaps our intuition, all human faces
are in fact very similar, which allows an easy recuperation of essential components from a quite small
database and a rapid reconstruction of any face, man or woman, European, Asian or African. Will it be
possible to construct a virtual portrait Babel Archive1, containing all real and virtual human portraits?
Besides calculating and experimenting components, which were obtained using different image processing
techniques, a set of more trivial statistical calculations were also made, using the portrait database from
the project. Average, standard deviation, skew and kurtosis portraits were calculated and analyzed, and
very interesting results were achieved. It was discovered that statistical portraits, such as average or
standard deviation, for different groups, for example men and women, have different characteristics,
which could be identified as representing those group characteristics, which corresponds to what could be
expected. But at the same time it was observed that a mixed group of only about 50 persons, including
individuals from all groups, drives to an average and other statistical portraits which are nearly not
distinguishable from the total. Let's just concentrate on the average portrait because it the simplest and try
to reason what the results might signify. Apparently having 50, 100, 200, 400, or eventually one million
persons appears to give exactly the same average portrait. This allows us to believe that the statistical
portraits that we calculated, in particular the average portrait could be presented as the image of
Humanity. Although this belief could be better evidenced with an enlarged database, just containing more
Africans and Asians, the results which we obtained with statistical portraits, in pair with the described
results with reconstruction of human portraits using components, give us enough fundaments to state
that the average portrait calculated could be seen as the humanity average. The same arguments could be
applied for other statistical portraits.
Instead of an infinite number of faces could we come into a unique image as a representation of Mankind?
©Renato Roque, 2010
1
Babel Library is a very famous José Luís Borges’s story, where he addresses the infinite concept and describes an imaginary infinite library – Babel
Library - which would contain all books, all texts ever written, in the past, present or future, in all languages, by Humanity.