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RE: Keykode with PRINT




Hello,

The Technical Research and Development Division of the National Film Board 
of Canada, were responsible for the development, in collaboration with 
Research in Motion of Waterloo, Ont. of the DigiSync Edgecode Reader and 
Decoder technology some years ago. (see SMPTE Journal, May 1991, pp. 
342-346; Eastman Key Notes, December 1994; Post, October 1991, pp. 
34-36,45).

At a number of seminars, sponsored by Eastman Kodak in various parts of 
North America, we have very early pointed out the importance of Laboratories 
printing the full edge on 16 and 35mm motion picture film.  At the time, the 
edgecodes were not always printed in the middle between the perfs, but 
sometimes also close to the perf. in 16mm. This resulted in light spilling 
and interfering with reproduction of the barcode. Also, the level of 
exposure must be controlled on the printer used.

Motion picture printers were not equipped to print along the edges used 
today for barcodes, and require a retrofit unit to provide adjustable light 
output and a wide enough slit to cover all barcode locations.

We built several units ourselves, (see photograph in Post, October 1991, 
p45)  which have since been used on our Bell&Howell Model C printers.  We 
have offered to share the design for a nominal amount or to have them built 
here in Montreal, for any laboratory which needs such units, at a cost of a 
couple of hundred dollars. The lightsource and fiber optic cable to the unit 
are also readily available.

In fact, when you receive dailies that are faint, unevenly exposed from 
splice to splice, or which display a black track area of varying width, you 
will want to point out that to the Laboratory that printed the dailies, that 
their work does not meet the quality requirements for readabilty.

The other suspect is edge fog.  In the negative, this looks like waves of 
random or recurring patterns of black exposure which fan out from the edges 
of the film, and appear particularly at the starts and ends of camera reels. 
 In dailies prints, they look the opposite, waves of white which fan out 
from the edge.  Edge fog can be prevented by loading camera cassettes in 
darkness. Or use care in the laboratory darkroom, using no or only safe 
light sources and no flash lights and using caution in not allowing 
prolonged exposure while the film sits on rewinds or on the machine, waiting 
to be stapled onto the previous reel going into the processor.

Negative cutters are usually on the lookout for image area problems, a 
little awareness on their part, in asuring that edgecodes are readable will 
also help assure that readable addresses for shots are always available 
where needed.


We welcome any questions or requests for help:

Ed H. Zwaneveld
Technical Research and Development
National Film Board of Canada
125 rue Houde, T-3
Saint Laurent, PQ. H4N 2J3
Canada
tel 1-514-283-9143
fax: 1-514-283-0278
email: e.ha.zwaneveld at nfb-onf.ca
 ----------
From: Dave Corbitt
To: telecine group
Cc: Bill Topazio; Steve Coffey; Joanne Gross; Jerry Haggart
Subject: Keykode with PRINT
Date: Thursday, July 25, 1996 10:25AM

                      Subject:                              Time:  9:33 AM
  OFFICE MEMO         Keykode with PRINT                    Date:  7/25/96

To all,
We have been working on a feature job recently but the elements we get for
transfer are 35mm print copies of the OCN reels.  We are required to read 
the
keykode from these print dailies and it seems like each reel has different
problems.  Some of the print reels are spliced together so we need to read 
the
keykode numbers at or close to the cuts.  These are not finished edit 
material
so the cuts are usually a few feet before needed picture so if the keykode 
is
reading at least 50% of the bar codes it should be accurate enough to dump
into AVID for off line cutting. The edge density varies from roll to roll 
and
even within the same roll changes enough to cause the keykode head to need
constant adjustment to get a reasonable amount of the bar codes to read. 
 Some
of the film exhibits washed out keykode and others have what looks like a
flare drifting in and out of the keykode area.  Since this is a print of the
OCN I can only assume that the OCN has symptoms of light leakage along the
edges of the film or the Keykode of the OCN isn't being properly printed
through to the print.  We are using Keylink for keykode reading and 
generation
of Flex Files and putting burned in windows on the 3/4 copies.  Most of our
experience in the past has been with OCN which is usually flawless with
Keylink.  What have been the experiences of the TIG members  under these 
kinds
of conditions?
Dave Corbitt / Manhattan Transfer

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