October 18, 1993
Chairman, Joint Experts Group on Interoperability
Eastman Kodak Co.
Bldg. 5, 4th Floor
1447 St. Paul St.
Rochester, NY 14653-7102
Dear Mr. Sanderson:
As you know, I represented ACM SIGGRAPH at last week's ACATS Interoperability
Review in Washington D.C. I found the meeting to be extremely informative.
The ACM SIGGRAPH committee on ATV is adamantly opposed to any form of interlace
digital HDTV output on consumer-level devices. We believe that progressive scan devices
are the only feasible displays for information coming from the National Information
Infrastructure (NII) and other computer-based services. We do not believe that interlace
sets can be used in this context because one would either have to view a display with
horrible interlace flicker (which is enough to make one turn one's head away) or halve the
vertical resolution, yielding an impractical 32x9 aspect ratio for text and
computer-generated image use. Furthermore, we believe that an interim standard allowing
interlace would greatly impair the access to the NII by the segment of Americans who
cannot afford both a computer display and a digital HDTV set. Thus, we are firmly against
any interlace standard for even an interim period.
The Grand Alliance does not directly address the NII compatibility issue other than to
point to the optional other progressive standards it is embracing. Allowing any interlace
option is tantamount to eliminating the other options for our lifetimes, since a cheaper,
non-compatible standard is embraced and produced first. The computer community I
represent has spent the past 20 years suffering with the incompatibility of interlace
television and computers. Now is the time to fuse computing and television by adopting
progressive scan as the one acceptable method of display.
Requiring progressive scan on a consumer set does not, however, necessitate progressive
scan cameras or broadcast. The consumer set will have enough memory inside it to scan
out video in any way from signals received in any order. The consumer set simply has to
display in progressive format so that it doesn't flicker unacceptable with NII-type
information. Virtually all computers put out progressive scan and, eventually, cameras
and broadcast equipment will follow. Consumer video cassette recorders (VCRs) could
similarly feed a variety of compression techniques (including interlace) into progressive
scan consumer sets, although interlace would destroy or cause any NII-type information
We believe that achieving consensus on progressive scan and NII compatibility is so
critical that any additional time spent debating the issue is well worth it.. We urge you to
continue the debate in good faith and examine all the issues, including the new ones
brought up last week. This is not a time for haste.
Thomas A. DeFanti
Chair, ACM SIGGRAPH Committee on ATV
Professor and Director
The Electronic Visualization Laboratory
Electrical Engineering and Computer Science Department
University of Illinois at Chicago
851 S. Morgan St., Room 1120
Chicago, IL 60607-7053
cc: Richard Wiley
Wiley, Rein & Fielding
1776 K Street NW
Congressman Edward J. Markey
2133 Rayburn House Office Bldg.
Washington, DC 20515
Chair, ACM SIGGRAPH