[opendtv] Re: ClearLCD adaptive dual-pulse
- From: "Adam M. Costello" <opendtv.amc+0+@xxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sun, 21 Jan 2007 07:44:15 +0000
Craig Birkmaier <craig@xxxxxxxxx> wrote:
> Here is an excerpt from the SMPTE Task Force Report on Digital Image
> Architecture that explains the perception of flicker by the human
> visual systems:
Thanks!
Jeroen Stessen <jeroen.stessen@xxxxxxxxxxx> wrote:
> > ClearLCD is the only non-CRT TV technology I've heard of that
> > even attempts to retain the impulse characteristic of CRTs.
>
> Well, some plasmas come reasonably close, but not quite,
I hadn't heard that. Do you know which ones? All the explanations of
plasma TV that I've seen suggest that the subfields are spread across
most of the frame-time.
> and OLED could do it, and SED certainly promises to do it too.
SED looks potentially great, but I've read that it's supposedly been
around the corner for seven years, so I'm hesitant to wait for it.
> And then there are many variants of motion-improved LCDs: scanning
> backlight, blinking backlight, black field insertion, grey field
> insertion, and increased frame rate (to 120 Hz). The latter
> development is happening very fast, because it is the only solution
> that does not create a flicker problem.
It's amazing to contemplate a display that can fabricate 96 (= 120 - 24)
two-megapixel in-between frames per second.
> > I guess ClearLCD's solution to the flicker/judder problem is related
> > to something called "adaptive dual-pulse" backlighting, but I have
> > been unable to find any details about it. Can you (yet) tell us
> > anything about that?
>
> Have you read paper 54.4 from the same SID 2006 ?! It was presented by
> Pierre de Greef, who is now with NXP. Pierre has also published an
> on-line paper in Journal of the SID.
I'm not a member of SID (I'm not in the display business at all). I
could buy the paper for $15, but that seems a little steep for one paper
(ten pages?), and I doubt any of that money would go to any of the
people who wrote, reviewed, or edited the paper. Where would that money
go, and for what? (I have the same concerns about the ACM and IEEE.
How is restricting access to research results helping these industries?)
> making the on-time shorter is only relevant to the point where
> the motion smear due to integration on the retina of the tracking
> eye becomes insignificant compared to the motion blur due to
> integration of moving objects on the light sensitive surface of the
> camera. Because the typical camera uses a long shutter time (I think
> typically between 5 and 16 ms), the images themselves are already
> blurred.
>
> Further reduction is only relevant for moving images that are sharper
> than what the typical movie producer delivers.
People use their home displays to watch things other than movies.
Do television cameras also use long shutters? What about live TV,
where you don't have as much control over the shots? What about
sports--wouldn't you want a fast shutter for that? And then there's
computer-generated video (games) where the camera is imaginary and by
default has an infinitely fast shutter.
Anyway, thanks for filling in some details regarding ClearLCD!
AMC
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