In article <telecom25.92.10@telecom-digest.org>, DLR
<news22@raleighthings.com> wrote:
>> I think the "breakthrough" happened a lot earlier. I recall watching
>> what I seem to recall to be a Formula 1 race where a tire company logo
>> was 'painted' on the pavement, in front of the start line. The logo
>> disappeared after the race started. This was at least 3 years ago.
> Actually I'd bet it was the yellow first down line used in football
> telecasts that started it all. Once a marketing wiz noticed what was
> happening they starting coming up with all kinds of things to
> superimpose. I'm fairly certain those small ads on the backstop to the
> side of the view of the batter in major league base ball games is
> superimposed on a specially colored panel. It keeps changing, there
> are a LOT of different displays, I can see no lines from rotating
> panels, and at times with "special views" the area is blank.
The ads on the backstop -- also at tennis court-side, and other
similar places -- have been around for a _long_ time. The technology
employed was _commercially_ deployed back in the mid 1960s for
U.S. television. known as 'chroma-key', you could use it to drop in a
'replacement' image for anything that was in the scene of a particular
color. Usually, the gear was set to trigger on a fairly narrow range
of blue. Blue was the commonly-used color because it was not a
component of 'flesh tones'.
To make the insert of the replacement image 'believable', the camera
that provided the original scene needed to hold a fixed view of that
scene. You know "something's funny" when, for example, one part of
the image zooms in, while another part _doesn't_. <grin>
Note: The original chroma-key technology was pure analog, some early
hardware was employing vacuum tubes. It was only a little more
complex than the circuitry in the basic 'special effects generator'
used for "split-screen" "corner inserts", etc. In fact, it shared
most of the circuitry with the special-effects generator.
Robert Bonomi (bonomi@host122.r-bonomi.com)