Preprint available on ICA of time-varying natural images

[Dan Ruderman]

The following preprint is available via the web:

Independent component analysis of image sequences yields
spatiotemporal filters similar to simple cells in primary
visual cortex

J.H. van Hateren and D.L. Ruderman

Proc. R. Soc. Lond. B, in press


Abstract

Simple cells in primary visual cortex process incoming visual
information with receptive fields localized in space and time,
bandpass in spatial and temporal frequency, tuned in orientation,
and commonly selective for the direction of movement. It is shown
that performing independent component analysis on video sequences
of natural scenes produces results with qualitatively similar
spatiotemporal properties. Whereas the independent components of
video resemble moving edges or bars, the independent component
filters, i.e. the analogues of receptive fields, resemble moving
sinusoids windowed by steady gaussian envelopes. Contrary to earlier
ICA results on static images, which gave only filters at the finest
possible spatial scale, the spatiotemporal analysis yields filters
at a range of spatial and temporal scales. Filters centered at low
spatial frequencies are generally tuned to faster movement than those
at high spatial frequencies.


http://hlab.phys.rug.nl/papers/pvideow.html