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Posted by ~P~ on 04/14/06 18:30
Jeff,
DECAY TIME: Look it up, it's all related to phosphor based CRT displays,
not digital technologies. When a phosphor is struck with a charged
particle, it lights up, then fades out. LCD is not phosphor based, nor is
DLP, or LCoS. Plasma is... I wonder how that would affect not 60hz rates?
But, with LCD, there is no decay of the image over time because the pixels
maintain a specific state for the entire time. If a LCD operated at 1/10hz.
That's one frame every 10 seconds - it would display that frame and then
wait for the next frame. It would not fade out, it would not go to black,
it would not have a color change, or a light intesity change. It would be
like me putting a book on a shelf - it would sit on that shelf until I took
it down. It wouldn't change or go away, it would just sit there. 10
seconds later, when I pulled that book down and put up a new book, that new
book would happily sit there until I took it down - 10 seconds later.
Telling it to go to a new state has to do with pixel response time, not
refresh rate. This is a very serious issue with LCD but much less so with
other digital display technologies. Lower refresh rates are actually
handled a bit better by LCD displays since they aren't asked to make as many
changes per second as they are with 60hz rates. It is common that people
see 8ms response times rated for pixels, and don't realize that is a full
on/full off measurement. The real challenge for the LCD pixels and where
they are slow is going from slightly on, to almost all the way on or
vice-versa. The intermediary changes are what take the most time. This is
what results in most of the smearing. Artifacts should only come from poor
processing.
NOTE: Strobing indicates that pixels go to black prior to going to a new
state - this is not the case. They go from 10% red to 20% red without first
going to black. Accuracy does not create strobing. Pixel decay, from CRTs,
that is to quick DOES cause strobing. But, I'm not talking CRT and to many
people are stuck in a CRT world.
I'm not disagreeing at all with issues related to motion smearing due to
poor pixel response time. I am saying that at 24hz we still would likely
have issues with LCD because pixel response is a bit slow - no matter what.
But, this would possibly be less dramatic than it is with 60hz processing.
With DLP and LCD projection where response time is much faster, we likely
wouldn't see any smearing issues and the persistentcy of frames allows
perfect 24hz reproduction - identical to original films.
I know you want to argue this, and it is possible the slowest we will ever
see is displays rated for 48hz output. But, we will see 24hz output from
Blu-ray this year. This will be one of the first times people will see
that, and then we can judge for ourselves. I am hoping we will see true
24hz displays, but it may not be practical since processing is always
required all over the place with digital displays and chips have to be
developed to handle that processing. Optoma HD81? Meh, may take longer for
my point to be made... or fully rebuked.
"Jeff Rife" <wevsr@nabs.net> wrote in message
news:MPG.1ea8ed8d68c73bfe98a46d@news.nabs.net...
And, once again, you show your complete lack of knowledge. It takes
close to 1/30th of a second to change most LCD pixels. The fact that
this is *more* time than the refresh rate of 1/60th of a second is why
the artifacts are smearing instead of strobing. A CRT with such a slow
decay rate for its phosphor will have the same effect.
If LCDs ever get really, really fast, then you'll start to see some
strobing artifacts, because despite your squawking to the contrary,
the entire display is *not* refreshed at the same time. This is also
why a 24Hz refresh would start to show strobing and flicker on an LCD:
because the pixel decay time would finally be below the refresh rate.
--
Jeff Rife |
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