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The color wheel camera
and the system that it was developed for can only be appreciated if one
considers the state of the technology at the time (circa 1985).
Consider that video
cameras at that time were mostly BW and used vidicon tubes: CCDs were just
reaching the industrial level, were expensive, and of not very high quality.
The available color
cameras (NTSC, single tube = << 160 TVL) were expensive, and of low
Flat bed scanners were
prohibitively expensive (>> $1K) and were mostly BW; there were a few hand
scanners, but of limited utility & quality).
To capture high quality
color images into a computer would have required 3 tube studio/industrial
cameras costing many thousands of dollars; even then, with few exceptions
that camera would have had the limitation of being NTSC resolution (330
TVL = 440 pixels).
Our color wheel camera
consisted of an inexpensive vidicon BW camera with a resolution of ~ 550
TVL (TV Lines); adding a rotating color filter controlled by a special
frame grabber card in the PC we could capture a 730 pixel (H) x 485 pixel
(V) 64-K colors (16 million if we had used a 24 bit capture card).
Compared to the single
tube color camera which required 3 pixels (R,G,B ) to equal 1 color
pixel, the color wheel system was perceptually 5 to 6 times greater.
Also consider: because
the color wheel system used only one tube, there was no color registration
required as was the case with all 3-tube cameras (a time consuming ritual
done several times a day).
To put this camera
into today's (1997) prospective: given the COSTS, there are still no cameras
of equal or better performance available; however, that gap is closing
as I write this! --gaw 1997
 Color pixel
ran across an article in the Summer 1997 issue of Invention
& Technology (p-52) entitled: "The Color War goes to the Moon."
It related how CBS's 1953 sequential color TV technology had been used
on the Apollo moon landings. And, though Westinghouse
had developed the early cameras, RCA delivered
the final version to NASA. The irony was that
in 1953, the FCC chose RCA's NTSC color TV
system to be the U.S. television standard over CBS's sequential color system.
The color wheel in the article looked very
familiar; it looked a lot like the camera I designed and built for Sarkis
Zartarian's "Com Club" project while at IBM
|Since I had designed our frame buffer (using
NEC's new serial video ram, 224-kbytes) I was able to incorporate the sequential
buffering as well as READ/MODIFY WRITE to use other filter (complementary)
colors. The clear, yellow, cyan would have been a GAS!
To implement the color wheel and avoid "reinventing
the wheel," we went to NASA for assistance, who obligingly sent us a copy
of the Space Shuttle manual (odd numbered pages only) which gave a cursory
discussion of the camera. We then tried to contact the, then, camera's
prime contractor--RCA, with them stone-walling
us. Finally, NASA arranged a conference call with two of the
engineers responsible for the design: getting any information was like
pulling teeth--mine. It was as hard as getting the people at IBM-Boca
to talk to us about PCs.
I finally had to
buy a book written by one of the original designers of the PC to get any
information. "Interfacing to the IBM Personal Computer," 1st
Ed., 1984, Eggebrecht, Howard W. Sams ISBN: 0-672-22027-X
We were using vidicons--as did RCA,
et al. --with their undesirable lag and "wipe-down" readout properties.
CCD cameras were starting to be practical but not in the price range IBM
would consider for this type of product. However, the next
generation version or the one after that--we planed to use CCDs.
|So we Improvised!
|The color wheel shape
we choose was very much like the 6 phase pattern that I once used in an
electrostatic resolver used for non-contact reading of needle position
on a remote power meter.
|Our competition (Charlie K____) within--IBM--was
doing his stuff in NTSC and needed 8 full-sized
cards in an expansion unit to do what we were doing with our single card;
and we were working in RGB space to do overlay.
He had written a paper on inserting overlay
directly into NTSC, using an algorithm that
determined the proper subcarrier phase for the overlaid video--mumble,
mumble (hardware of course--at that time--we were all working on XT platforms,
Ugh!). It needed a highly accurate xtal timebase--I have no idea
why. His excuse for why it looked like SHIT was "...the oscillator's drift,
(more) mumble mumble..."
|We demoed our stuff
and the camera to three site managers at IBM who were there to determine
our status--to CAN or not to CAN--our Ass, and who just happen
to be good friends of our "NTSC" competitor.
I will never forget
the scene: They walked in, obligatory 'pleasant chit chat,' and all three
lined up in front of the SONY KV-1270-Q hi-res RGB monitor. I turned on
the light box which held a colorful transparency, the camera spun-up, and
finally I turned on the monitor; as the monitor warmed up, I walked behind
and to the side of these three guys and waited. As the image came on the
screen, there was an audible gasp from all three, and--so Help-me-GOD--at
the same time they all rose up on their tip toes: talk about body language!
If they had risen any higher they would have been Levitating!
The image was perfect!
To prove we weren't
"hosin-em," I went over and put in several other transparencies.
They said absolutely
They sat through the
rest of the demo: voice mail; store & forward video mail; video conferencing
in the form of live whiteboard annotation; voice reco--that worked without
a head set (keyboard commands). It was Outstanding!.
They thanked us politely
for our time, and left.
The project was CANCELED!
--Sarkis took early retirement.
Zartarian was a Damn Genius!
He pulled it all together and It Worked!
His performance through the entire project
was what TRUE Management is really all about (or should be about).
He Delegated to each person the work they were best at, and most importantly,
WANTED to do. He defined the mission, gave his people the necessary
resources, shielded them from outside interference, and got the Hell-outa-the-way!
His weakness--which doomed him: he was not
a "glad-hander," he couldn't or wouldn't "Network" within IBM.
Sarkis was great at selling it to the USER, but NOT to IBM
History is replete with proof that the best
ideas don't necessarily win: it's not a technology question as much as
it's a people/political question--Bummer!
Sarkis was a Visionary!
Back in the early
1980s he saw the future; many of the things that we use in our everyday
lives and take for granted, he had working on a desktop PC and PC AT.
His dream was that
of early technology being used for Remote Medicine. He wrote and lectured
widely an the subject. IBM chose not to listen...
|System Elements: (circa 1984/85)
Voice Reco sans headset
Store & Forward Voice Mail
Store & Forward Video Mail
Color Wheel Camera: Very High Resolution
R G B color wheel
NEC Serial Video RAM Frame Buffer (224-kbytes/IC)
|Next Generation plans:
Color Wheel: Clear, Yellow,
Cyan color wheel = 3 x Green, 2 x Red, 2 x Blue
24 bit/32 bit Frame Buffer
Modem speed enhancement: "Shotgunning"
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