a
virus for art only : computer virus project 2.0 
Rather
than being the kind of virus that destroys computers, Joseph Nechvatal's viral
works infect images. Viruses have a nasty reputation due to negative associations
with human health and computer hard drive failure, but are also part of the robustness
of natural systems. Spreading viruses, which require the transmission and mutation
of system data, are an integral part of the survival of living species.
Nechvatal's
Computer Virus Project 2.0 follows the lines of previous work from 1992 - where
an unpredictable progressive virus operates on a degradation or transformation
of an image. Using a C++ framework, Joseph Nechvatal and his programmer/collaborator
Stephane Sikora have brought Nechvatal's earlier project into the realm of artificial
life (A-Life) i.e. into a synthetic system that exhibits behaviors characteristic
of natural living systems.
With
Computer Virus Project 2.0, elements of artificial life have been introduced in
that viruses are modeled to be autonomous agents living in/off the image. The
project simulates a population of active viruses functioning as an analogy of
a viral biological system. The hosts of the virus are digital files based on computer-robotic
assisted paintings. Among the different techniques used are models that result
from embodied artificial intelligence and the paradigm of genetic programming.
the model
The world is modeled as an image via a set of pixels. Every pixel's color
is defined by R,G,B real number vectors which represent the red, green and blue
components of every pixel's color. The image world has no edges. Every square
on the edge of the image is adjacent to another on the opposite edge. A virus
can move around the image and impact the image world as different colors actually
correspond to resources used for survival by the viruses.
virus
behavior
The behavior of a virus is modeled as a generated looping activity
that is typical of situated artificial intelligence work. A virus will pick up
information from its environment, decide on a course of action, and carry it out.
The loop is simplified here because of the abstract character of the simulacrum.
Viral instructions provide different possibilities for executing instructions
according to the environmental conditions in which the virus is living. A virus
will perceive the pixel it is on and the eight adjacent ones. It can get information
on its color and on the possible presence of other viruses. In order to decide
on a course of action, each virus is programmed with a set of randomized instructions
of different kinds; some relate to direction, others to a change in the color
of the current pixel (the one the virus is in). Others control the implementation
of the program and carry out tests.
Once
the program has been executed, following actions to be carried out randomly arise.
As the virus executes them, it moves to one of the adjacent squares and changes
the current pixel. It can even reproduce itself (reproduction here results from
the instruction 'divide'. A virus that carries out that instruction will produce
a replica of itself - although slightly altered. Its genome-program changes with
the mutation operator). In addition to these changes, every cycle produces a change
in the energy level of the virus. The virus will lose a set amount of energy with
every run, and when it runs out of energy, it dies (i.e. it disappears). In order
to survive, a virus needs to pick up energy, which it can only do by degrading
the image. The more it changes the color of a pixel, the more energy it acquires.
The difference between the color before and after is calculated. We can see from
a virus's behavior and direction whether it will be more or less adaptable - more
or less able to survive. There is a maximum number of viruses that can be present
simultaneously (usually 1000). When that number is reached, the 'divide' instruction
is ignored. If the virus has enough energy it will move around randomly, otherwise
it will follow its favorite color and absorb part of the red component of the
pixel it is on.
system
dynamics
A viral attack will generally develop as follows:
a) A
world is created from an image.
b) A population of viruses is generated randomly
and introduced into the image. Every virus takes on its very own behavior, as
the program defines them fortuitously.
c) Once the viruses have been placed
in an image, the attack can start. It will consist of a series of action cycles
that will only come to an end when there is no virus left alive (or after a given
time limit). Many different dynamics can be seen that depend on the parameterization
of the experiment.
dynamic
parameters
a) filtering
The viruses act as local filters on the image. The modification of a pixel's color
will influence the subsequent dynamics, and it can influence the virus's demeanor
and its trajectory. For example, a virus attracted by the intensity of the red
component in pixels reduces the intensity of the color if it executes 'eat red'
- and will tend to avoid the areas it has already visited. In order to have some
control over the global effect, Joseph Nechvatal can define a set of active instructions;
those which will be part of the genome program for the virus.
b)
reproduction, evolution, and adaptation.
The instruction 'divide' will reproduce
replicas of a virus (slightly different through mutation). The creation of these
replicas will immediately trigger a considerable loss of energy in the virus.
This means that a virus that is not capable of drawing energy from its environment
will not survive much longer after it has carried out the 'divide' mandate. And
so will its replicas.
On
the other hand, the fact that these replicas are not identical to the original
offers the possibility of examining new types of behavior. When an adapted individual
appears, it can remain in the image for quite some while. If it executes the 'divide'
instruction, its descendants will most probably be equally adapted. The number
of these agents will generally increase exponentially, and thereby create a large
population of very active viruses.
Joseph Nechvatal
http://www.nechvatal.net
Credits: C++ programming Stephane
Sikora
