ahmad@icsib18 (Subutai Ahmad) (07/18/90)
The following technical report is available:
A Network for Extracting the Locations of Point Clusters
Using Selective Attention
by
Subutai Ahmad & Stephen Omohundro
International Computer Science Institute
ICSI Technical Report #90-011
Abstract
This report explores the problem of dynamically computing visual
relations in connectionist systems. It concentrates on the task of
learning whether three clumps of points in a 256x256 image form an
equilateral triangle. We argue that feed-forward networks for solving
this task would not scale well to images of this size. One reason for
this is that local information does not contribute to the solution: it
is necessary to compute relational information such as the distances
between points. Our solution implements a mechanism for dynamically
extracting the locations of the point clusters. It consists of an
efficient focus of attention mechanism and a cluster detection scheme.
The focus of attention mechanism allows the system to select any
circular portion of the image in constant time. The cluster detector
directs the focus of attention to clusters in the image. These two
mechanisms are used to sequentially extract the relevant coordinates.
With this new representation (locations of the points) very few
training examples are required to learn the correct function. The
resulting network is also very compact: the number of required weights
is proportional to the number of input pixels.
Copies can be obtained in one of two ways:
1) ftp a postscript copy from a.cs.uiuc.edu. The file is
ahmad.tr90-11.ps.Z in the tmp directory. Here are directions in case
you are unfamiliar with ftp:
unix:2> ftp a.cs.uiuc.edu
Connected to a.cs.uiuc.edu.
Name (a.cs.uiuc.edu:): anonymous
331 Guest login ok, send ident as password.
Password: ident
230 Guest login ok, access restrictions apply.
ftp> cd tmp
ftp> binary
ftp> get ahmad.tr90-11.ps.Z
ftp> quit
unix:4> uncompress ahmad.tr90-11.ps.Z
unix:5> lpr ahmad.tr90-11.ps
2) Order a hard copy from ICSI:
The cost is $1.75 per copy for postage and handling. Please enclose
your check with the order. Charges will be waived for ICSI sponsors
and for institutions that have exchange agreements with the Institute.
Make checks payable (in U.S. Dollars only) to "ICSI" and send to:
International Computer Science Institute
1947 Center Street, Suite 600
Berkeley, CA 94704
Be sure to mention TR 90-011 and include your physical address.
--Subutai Ahmad
ahmad@icsi.berkeley.edu