10 Feb
2011
10 Feb
'11
10:56 a.m.
On 2011 Feb 10, at 1:53 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.
Sure, and the newspaper is always right ;-)
Since TV is/was purely analog, the horizontal resolution only depend
on the bandwith and the beam focus.
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
No, they didn't. Maybe in the US, but usually they refered to the
number of scan lines ("vertical resolution" if you like) and the
bandwidth (e.g. 5.5 MHz here or around 10 MHz in France).
Geez.
Systems here were described in terms of scan lines and bandwidth too.
But the more detailed analyses being done at the time involved as I
have quoted. The book was not a newspaper, nor is it a marketing
brochure or paperback tract. It's a 500-page hardcover book from a
reputable publisher, targeted at engineers, giving a quite thorough
technical compendium of the state of the art at the time. I would be
surprised if "picture element" originated with this book, not that that
would obviate my point.
You can lead a horse to water...
On Wed, 9 Feb 2011, Brent Hilpert wrote:
No, you've got that wrong. The bits only affect the starting and end
point of a vector but *not* the vector itself!
I am well aware of how vector displays work.
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.) 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? 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.
Well, the vertical dimension depends of the size of the CRT, the
number of scan lines remains the same (625 lines according to the
CCIR). Some of these lines are "drawn" outside the visible area of the
CRT as they contain the vertical sync and the blanking period (the B
and S in (C)VBS).
"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."
Sounds like marketing figures...