This study is an attempt to understand the major functions of early vision by considering how
various components cooperate in preparing visual information to organize our perceptions of the
world around us. To this end, and with the cooperation of SRI's Machine Vision Group, we have
assembled some of these functions in a computational working model, which can graphically
display the spatial structure of the information at a given stage of the visual process, in the form of a
two-dimensional intensity array (or "image"). The development of such a capability should facilitate
the study and comparison of retinal and cortical inputs and outputs of spatial information.
The individual components of the model are well known, and the relations among them are based
on available data from the literature. However, two aspects of this study seem novel. One is the
exploitation of powerful, state-of-the-art tools of computational vision, such as Symbolics
3600-series LISP machines, to create and display our results. These tools were developed primarily
for artificial intelligence purposes; they have rarely been used for basic studies in human vision.
Another important novelty is the combination, into a single, integrated emulation, of the following
properties of the visual process:
. Inhomogeneous filtering by retinal receptive fields. . Re-mapping of visual space by the retinocortical projection. . Image analysis by receptive fields of the striate cortex. . Multiple fixations of a single scene.
Each of these mechanisms has been studied in detail previously, but they have scarcely been
interrelated. Taking a different approach, we use a relatively broad-brush description of each to
study how they could all behave in concert.