Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!think.com!yale!bunker!wtm
From: reinoud@duteca.uucp (Reinoud Lamberts)
Newsgroups: misc.handicap
Subject: Re: Tactile Diagrams from Print?
Message-ID: <15218@handicap.news>
Date: 25 Apr 91 17:03:43 GMT
Sender: wtm@bunker.isc-br.com
Reply-To: reinoud@duteca.uucp (Reinoud Lamberts)
Organization: Delft University of Technology, Dept. of Electrical Engineering
Lines: 27
Approved: wtm@hnews.fidonet.org
Fidonet: Blink Talk Conference

Index Number: 15218

Some time ago I discovered that some copiers and laser printers
produce output with distinctly perceptible edges on the
boundaries between black and white parts. A blind girl, with a
much keener sense of touch than I have, confirmed that she could
interpret some ordinary laser-printed images.

The most interesting results were obtained with images processed
by computer. A portrait processed with a high quality edge
detection filter she readily recognized as such, and she could
even detect that the portrait was of a woman.

On the techical part: to get perceptible edges a rather thick
layer of toner is required. Therefore best results can be
expected with cheap copiers and laser printers. Maybe it is
possible to adjust the toner thickness on a device dedicated to
tactile output.

Reception of the misc.handicap group is very erratic on this
site, so please send a copy of a posted reaction to me by email.

Regards,

- Reinoud

email: reinoud@duteca.et.tudelft.nl