9 Feb
2011
9 Feb
'11
8:57 p.m.
On 2011 Feb 9, at 2:17 AM, Christian Corti wrote:
I don't know why you would say it's not correct. The numbers are out of
the book and refer to the abilities of the then-current RMA TV
Committee standards for transmission, they account for things like
channel bandwidth.
It is a slightly different meaning than 'pixel' today, it's a measure
of resolution: that which can be resolved; rather than a fixed grid of
points on the image medium.
It's not an assertion by me, I'm just pointing out how these things
were characterised in 1940: even for analog systems they did so in
terms of a matrix or discrete count of "picture elements". There is a
whole chapter in the book on image analysis and it is more complex than
what I present here, it doesn't correspond 1:1 in the V dimension to
the number of scan lines for example.
"A single frame of 35mm motion picture film contains about 500,000
picture elements when exposed, developed and projected in the usual
manner."
"A fine 'contact' photographic print of 8*10in dimensions contains as
many as 50,000,000 picture elements."
On Tue, 8 Feb 2011, Brent Hilpert wrote:
I know what you mean here, so not to argue your point about the
analog process in the system under discussion, but I would like to
add an historical footnote: even analog raster-scan systems were
characterised in terms of "picture elements" going back to the very
early days of TV.
That's exactly the point: those Tektronix terminals/computers are not
raster-scan systems, you draw a line from here to there. The only
"limitation" is the addressing range for the start and end point
(either 10 or 12 bits). Speaking of the printer, AFAIK it's the
printer that determines the scanning speed and the resolution of the
rasterization process.
(And ultimately that 10 or 12 bits does place a maximum on the V*H
resolution of the drawn image.)
For that matter, how big are the pixels?
There
aren't any pixels. systems at the
time. The phrase "picture element" is used throughout.
The then-current transmission standard was characterised as 441 lines
by 400-600 picture elements per line, "that 3,000,000 to 6,000,000
elements must be sent
... which is not quite correct since the horizontal "resolution"
depends on the bandwidth, the beam spot size and the size of the
screen surface. in a
second", etc. The characteristics of other mediums such as
photographs are also presented in terms of picture elements.
?!? I know that the grain size matters, but where can I find those
picture elements on a film strip?