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Victim of a public schoo



I am in the process of writing Conspectus, a review of 1996 for Broadcast
Hardware International magazine. The following sneak preview may be of some
relevance to the current debate:

"Looking back to my NAB review, I see that I commented on the not-so-subtle
debates over sampling and compression algorithms, with manufacturers
arguing over the respective merits of 4:1:1, 4:2:2 and more. Remember
always that (analogue) Beta SP is, I would suggest, a universally
recognised standard of acceptable quality, even by those broadcasters who
do not use it, and that uses the equivalent of 4:1:1.

"There is a whole world of difference between post production and output
VTRs and the resolution they require. When the requirement is for image
manipulation then you must retain as much information as possible, which is
why big budget commercials are shot on 35mm film, transferred at 4:4:4
using a Cintel telecine, and up-sampled to even higher resolutions in the
colour processor.

"When the requirement is simply for something that looks good, though, then
it makes sense to go back to the eye and see what sort of resolution it
possesses. In the back of the eye there are two sorts of light sensors:
rods which are luminance detectors (with greatest sensitivity at around
500nm, which is green) and cones, which come in red, green and blue
varieties. Overall, though, rods are very much more sensitive than cones,
which is why as light levels drop so we lose colour perception.

"This burst of anatomy is simply the background to the fact that every
television engineer knows: viewers perceive a good picture from a sharp
luminance signal and little more than a wash of colour thrown over it. That
is how PAL, SECAM and NTSC can get away with the microscopic bandwidth
dedicated to colour, and why 4:1:1 recorders are perfectly acceptable for
transmission."

Or to put it simply, my view is that you guys in telecine cannot have too
much resolution. Keeping 4:4:4 through the post house will keep the quality
through each of the processes. Once the job is signed off, though, even
4:1:1 is better than you are likely to see when it gets to the home.

Until DVD comes along....

Dick Hobbs

PS on a point of information: in England, public school means private
school. I've lived here all my life and I still don't understand why.