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VISION-LIST Digest 1988 05 04
Vision-List Digest Wed May 4 11:12:06 PDT 1988
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Today's Topics:
INNS 89 Conference
Hexagonal vs. square tesselation
Contrast/Size Illusion
Re: Recording Visual Images
Recording Visual Images Revisited
Questions on visual areas of the cortex
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Date: Tue, 26 Apr 88 18:50:55 EDT
From: mike%bucasb.bu.edu@bu-it.bu.edu (Michael Cohen)
Subject: INNS 89 Conference
GOOD NEWS FOR THE NEURAL NETWORK COMMUNITY!
There are now over 2000 members of the International Neural Network Society
from 34 countries and 47 states of the U.S.A.
The INNS is thus beginning to fulfill its purpose of offering our
community an intellectual home of its own.
In particular, over 500 abstracts were submitted to the 1988 First
Annual INNS meeting in Boston, to be held on September 6--10, 1988, at
the Park Plaza Hotel. The abstracts cover the full spectrum of topics
in the neural network field.
While many are working hard on the final program and plans for the
1988 meeting, we also needed to plan further ahead. Accordingly, the
INNS Governing Board approved holding the Second Annual INNS Meeting
in Washington, DC, on September 5--9, 1989, and we have negotiated a
contract with the Omni Shoreham Hotel.
See you in Boston in '88 and Washington in '89!
Steve Grossberg, President, INNS
Demetri Psaltis, Vice President, INNS
Harold Szu, Secretary-Treasurer, INNS
Michael Cohen ---- Center for Adaptive Systems
Boston University (617-353-7857)
Email: mike@bucasb.bu.edu
Smail: Michael Cohen
Center for Adaptive System
Department of Mathematics, Boston University
111 Cummington Street
Boston, Mass 02215
------------------------------
Posted-From: The MITRE Corp., Bedford, MA
Subject: Hexagonal vs. square tesselation
Date: Wed, 27 Apr 88 12:36:02 EDT
From: jhs@mitre-bedford.arpa
I don't know if this constitutes a profound thought (ref: description of
content, this news group) or a dumb question, but here goes...
Has anybody looked at hexagonal close-pack pixel organization of images?
It seems to me that the stodgy old rectangular arrayof pixels is
unnatural, and we would get better pictures if we laid out pixels in a
hexagonal array the way God intended them to be. (sure to get a
reaction...)
I.e.
o o o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o instead of o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o o o
You can already see a difference -- the one on the left has the same
pixel density, but looks somehow smoother and more continuous than the
one on the right. I find it more "relaxing" to look at. My hunch is
that a picture built that way would look better for the same
information bandwidth than a rectangular one, especially on
unstructured images which did not emphasize rectangular shapes. I
would prefer to test the hypothesis with a true regular hexagon
layout, i.e. 60-degree angles and the whole "bit" (so to speak).
However, one could experiment with a hi-res display just by skipping
pixels to see if the diagonal skip pattern does in fact look better.
Not only does this obviate the development of a custom display for the
experiment, but it also has the advantage that the bandwidth is
obviously the same, whereas the true 60-degree version would have less
vertical height so would take a little more bandwidth to cover the
same area on a screen. (Height less by ratio of sqrt(3)/2 for same
number of pixels.)
If anybody tries this, I'd be interested in hearing how the results
come out. Please reply directly, as I don't read the mail from this
distribution list. (Also I have never worked with image processing
other than an occasional gedankenexperiment, so pardon me if the idea
is old hat.)
-John Sangster / jhs@mitre-bedford.arpa
[ Perhaps Golay has addressed this? As a side note, practically
all biological retinas have a hexagonal tesselation. This is likely
because hexagonal arrays result from the minimum energy packing of
bubbles (cells) on a plane. -pk- ]
------------------------------
Date: Wed 27 Apr 88 15:13:05-PDT
From: Ken Laws <LAWS@iu.ai.sri.com>
Subject: Contrast/Size Illusion
I'm not familiar with literature on the contrast/size illusion, but it
would seem amenable to the kind of explanation that Ginsburg proposes
for many illusions. Suppose that we bandpass filter the image, then
measure the distance between zero crossings or other edge measures.
It seems likely to me that changing the contrast might cause these
zero crossings to move in or out (assuming suitable nonlinearities in
the blurring or threshold functions). Witkin's scale-space tracking
was designed to get around such effects when measuring edge
postitions, although I grant that he was interested in more cluttered
imagery.
Michael Seibert of Boston U. recently presented a talk at Stanford on
a perceptual grouping method that reminds me of Ginsburg's
Fourier-based approach. Seibert's work made use of inflection points
rather than zero crossings, but the effect must be similar.
-- Ken
------------------------------
Subject: Re: Recording Visual Images
Date: Wed, 27 Apr 88 15:18:06 -0700
From: malcolm@spar-20.spar.slb.com
>> From: Wahner Brooks <wbrooks@yuma.arpa>
>> Subject: Recording Visual Images
>>
>> Can anyone provide me recommendations for film/lens/filters and
>> exposure durations that would record an image as the "average" human
>> eye would see it under both photopic and scotopic conditions?
Many years ago I remember a review of portrait lens for 35mm cameras claimed
that a lens that was equivalent to humans had a focal length of 75-90mm. I
don't remember how they arrived at this number but from my own experience
(with forshortening and such) this seems reasonable.
Cheers.
Malcolm
------------------------------
Date: Fri, 29 Apr 88 10:40:10 MDT
From: Wahner Brooks <wbrooks@yuma.arpa>
Subject: Recording Visual Images Revisited
Greetings Gentlepeople:
My appreciation to Shelly Glaser for his helpful reply to my
query (<vision@ads.cum>; dated 20 Apr 88). On reflection, my request
for help was too general to define the problem: specification of
photographic or (preferably) video equipment and recording media to
match the response of the "average" eye under light and dark
conditions. I'll have to forego brevity to restate the problem.
Yuma Proving Ground is a U.S. Army Test and Evaluation Command
installation charged with testing a large variety of defense material.
One of the many commodities we test in the Ordnance area is
pyrotechnic flares fired from guns or dropped from aircraft.
In the late '60's, I had a project to improve the method of
evaluating flare systems. The traditional method had been to measure
the intensity of a flare candle in a tunnel. Flares were then fired
in the field and tracked by cinetheodolites to obtain trajectory.
Using the inverse square law, illumination on the target was then
calculated. Acceptance was based on such criteria as "providing
2-moonlights equivalant!"
proved the extrapolation of tunnel data had little correlation with
the real world. Using a staticly suspended flare over a array of
aimed photocells, flame characteristics, paracute canopy reflections,
and smoke obscuration proved to have a major effect on illumination
actually reaching the ground. Based on their effort, YPG designed
and, with assistance from the Army's Feltman Lab at Picatinny Arsnal,
NJ, built a test range consisting of a large array (8,100 ft. square)
of photocells electronically connected in a ring matrix (cf. Pat. No.
3,936,839).
This range provided valuable information which led to new
designs of limited to preset threshold levels on the sensors).
Unfortunately, however, only part of the problem was addressed.
Developers and Users (the field army) still wanted to know what was
required to put "effective" illumination on the target.
The determination of illumination effectiveness was, and still
is, the use of "jury trials." A representative group of test subjects
would be stationed at different ranges and asked to identify targets,
or, given a number a number of poorly understood human factors
(including non-visual skills) into an already complicated problem.
We tried a number of schemes, including sensors on the target
aligned along several axies, a variety of telephotometers, and various
photographic and video cameras - such as was available in the
mid-'70's. We were unable to get even rough correlations with the
range data (vertical illumination component and flare/target angles).
Following the leads of a system error analysis, we found so many
variations in individual components that we just gave up. (Not being
a lab, and having a whole range of priorities, I can admit to that.)
I am relooking at the problem, in hopes technology and
research has offered advances in the last decade that might help. I
am particularly interested in video, since electronically recorded
imagery is so much easier to manipulate. The path we are following is
based on the belief that replacement of the jury with calibrateable
instruments would remove many messy human elements from the
equation.
This is not an application limited problem, of course. At
YPG, we are also concerned with the effectiveness of vehicle
headlights, aircraft landing lights, and other illuminators. I am
sure you can come up with a host of others.
Again, any help or assistance would be appreciated.
Wahner Brooks
------------------------------
From: mcvax!prlb2!ronse@uunet.UU.NET (Christian Ronse)
Subject: Questions on visual areas of the cortex
Keywords: Brodman 17..19, V1..5
Date: 29 Apr 88 07:43:49 GMT
Organization: Philips Research Laboratory, Brussels
When I read papers on the visual cortex, authors refer either to the striate
and prestriate areas, or to Brodman's areas 17, 18, and 19, or to visual
areas V1, ..., V5.
I know that striate = Brodman 17 = V1.
I suppose that prestriate = Brodman 18+19. Am I right?
Now, how do V2, ..., V5 relate to Brodman 18 & 19?
Christian Ronse maldoror@prlb2.UUCP
{uunet|philabs|mcvax|cernvax|...}!prlb2!{maldoror|ronse}
``Let us learn to dream gentlemen, and then we may perhaps find the truth.''
F.A. Kekule
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End of VISION-LIST
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