abstract = "Procedurally generated images and textures have been
widely explored in evolutionary art. One active
research direction in the field is the discovery of
suitable heuristics for measuring perceived
characteristics of evolved images. This is important in
order to help influence the nature of evolved images
and thereby evolve more meaningful and pleasing art. In
this regard, particular challenges exist for
quantifying aspects of style and shape. In an attempt
to bridge the divide between computer vision and
cognitive perception, we propose the use of measures
related to image spatial frequencies. Based on existing
research that uses power spectral density of spatial
frequencies as an effective metric for image
classification and retrieval, we posit that Fourier
decomposition can be effective for guiding image
evolution. We refine fitness measures based on Fourier
analysis and spatial frequency and apply them within a
genetic programming environment for image synthesis. We
implement fitness strategies using 2D Fourier power
spectra and phase, with the goal of evolving images
that share spectral properties of supplied target
images. Adaptations and extensions of the fitness
strategies are considered for their utility in art
systems. Experiments were conducted using a variety of
greyscale and colour target images, spatial fitness
criteria, and procedural texture languages. Results
were promising, in that some target images were
trivially evolved, while others were more challenging
to characterize. We also observed that some evolved
images which we found discordant and uncomfortable show
a previously identified spectral phenomenon. Future
research should further investigate this result, as it
could extend the use of 2D power spectra in fitness
evaluations to promote new aesthetic properties.",