The Computational Creativity Complex - Computational Creativity Research: Towards Creative Machines - page 67

interest points shared by the two images and can be translated into a measure of
image similarity.
Fitness-based tournament selection determines those genotypes that propagate
to the next generation and those genotypes that participate in crossover. One-point
crossover is used to allow for variable length offspring. Crossover is accomplished in
two stages: the first occurs at the filter level, so that the two genomes swap an integer
number of filters; the second occurs at the parameter level, so that filters on either
side of the cut point swap an integer number of parameters. By necessity, parameter
list length is preserved for each filter.
Mutation occurs at both the filter and parameter levels. Filter mutation is a whole-
sale change of a single filter (discrete values), while parameter mutation is a change
in one or more parameter values for a filter (continuous values).
Because there are potentially many ideal filter configurations for modeling any
given synset, sub-populations are used within each gene pool, allowing the evolu-
tionary mechanism to converge to multiple solutions. Limited migration between
sub-populations is allowed, with the exception that the most fit genotype per sub-
population is not allowed to migrate, and sub-population size balancing is enforced.
Figure 4.2 shows an example image produced by DARCI when given the concept
war as the stimulus.

Fig. 4.2 Image produced by DARCI to express the concept of war