The benefits of (non-perceived) flicker

Article: Lessons in Technology and Innovation from the iPad 3 Graphics and Display
By: dmsc (no.delete@this.more.spam), January 10, 2013 4:41 pm
Room: Moderated Discussions
Hi,

Anon (no.delete@this.email.com) on January 9, 2013 10:07 pm wrote:
> dmsc (no.delete@this.more.spam) on January 7, 2013 7:36 pm wrote:
> >...
> > Real Motion:

I see that my graph was garbled by the HTML, so it's repeated
again, just ignore the "_":


> > Real Motion:
> >
> > ___________/__
> > ________/_____
> > _____/________
> > __/___________
>
> BS, our eyes dont work at all like that, you are forgetting half of the 'system'..
>
> > Motion on a strobed display:
> >
> > ___________.__
> > ________._____
> > _____.________
> > __.___________
>
> Only if the backlight was on infinite brightness (and response time), again
> false and the same as above, our eyes would never see this anyway).
>
> > Motion on an LCD:
> >
> > ___________---__
> > ________---_____
> > _____---________
> > __---___________
>


> Also wrong, due to material persistence, how our eyes actually work, and the
> BIG elephant in the corner you seem to have completely forgotten, the motion
> blur present in many sources ;)

Yes, the sources sometimes have motion blur, but normally it's very
little.

Some references:

google "Temporal summation of moving images by the human visual system.",
there the author describes the fact that the human visual system integrates
the moving images *after* the detection of movements, in effect, tracking
moving objects.

In "LCD motion blur modeling and analysis" from Hao Pan, Xiao-Fan Feng,
Scott Daly the motion blur in LCDs is measured, and only 30% is from
LCD with slow 16ms responses, the 70% remaining is from hold-blur, which
is what we are talking.

>
> >
> > See? The LCD shows a jagged motion, and this is clearly perceptible.
>
> I can see that you dont understand what you are talking about, and have massivly over simplified
> a situation to arrive at the wrong conclusion, try a little actual research.
>
> > Current LCDs have transition times in the order of a couple of ms, so
> > all that you describe is non-existent.
>
> Not unless you believe their wildly optimistic 'marketing specs', otherwise it varies
> massively with degree of transition and amount of setting you will accept.

Measurements showed in the paper above.

>
> > What modern 120/240 Hz LCDs do is interpolate the frames using the
> > detected movement of the scene (for example, using motion-vectors
> > from the coded stream), and generate intermediate frames, showing
> > a more fluid motion.
>
> You have swallowed that marketing line hook line and sinker, havnt you? :)
> they DO do interpolation, however it does not work as you seem to believe.
> if it did, it would have its own problems with both non-locally decoded sources
> (ie: most), sources that contain motion blur (movies, some computer game output),
> and any fine detail movement (you do know mpeg motion vectors are only
> block-accurate, right?)

No, motion vectors are not block-acurate. In h264 motion you can have
up to 4 motion vectors for block and the precision is 1/4 pixel. The
motion vectors in the encoder are calculated minimizing the motion
flow, and also minimizing the total change between adjacent motion
vectors to encode less bits.

You are right that probably the current TVs don't use the source
motion vectors, as the displays also interpolate uncompressed HDMI
streams, but obtaining motion vectors from the image is not difficult.

In the paper "Perceptually-motivated Real-time Temporal Upsampling
of 3D Content for High-refresh-rate Displays" there are some real-time
algorithms for temporal upsampling.

>
> > Remember that also all current LCDs do frame interpolation in the
> > de-interlacer, needed to display the obsolete interlace material
> > being broadcast.
>
> aha, your complete lack of understanding now shows, interlacing is obsolete?
> you do not understand what it is and why it is used I can see..

Please, don't be obtuse. The interlaced material is obsolete because
INTERLACED DISPLAYS ARE NOT SOLD ANY MORE.

Any interlaced material MUST BE DE-INTERLACED TO SHOW ON CURRENT
DISPLAYS.

Understand?

> > > The problem isn't refresh rate, it's physical constraints on how fast LC material can respond to refresh.
> >
> > Not true. Current LCDs are much faster than old CRTs.
>
> Not true, there were CRTS much faster than current LCDS (and slower), there
> are also a huge crange for what is a current LCD. generalising much?

We are talking of TVs, not any display.

[....]

> > Most good LCDs use LED lighting, already PWM controlled for brightness, to
> > allow the big marketed contrast ratios. The TV simply synchronizes the PWM with
> > the display frame rate (at 120 or 240 Hz).
> >
> > Daniel.
>
> Most GOOD LCDs actually use CCFL (stress the good there), however plenty of OK LCDs use LED.
> synchronising to frame fate does NOT achieve what you think it does, except in a case where LCD
> material responded in a consistent and instantaneous manner, which of course it does not.

I don't know where are you, but here is difficult to even find CCFL
displays sold anymore, only really cheap models. You can't buy any >42"
CCFL display anymore, only LED ones.

>
> I am still waiting for a citation on this apparent use (and please no marketing statements..)

See the paper "LCD motion-blur analysis, perception, and reduction using synchronized
backlight flashing". Note that the author works for Sharp display technology.

Daniel.
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TopicPosted ByDate
Lessons in Technology and Innovation from the iPad 3 Graphics and DisplayDavid Kanter2013/01/01 04:14 AM
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              Games at 2048 x 1536? Can you tell?rwessel2013/01/03 11:56 AM
                Games at 2048 x 1536? Can you tell?rwessel2013/01/03 11:56 AM
                  Oh, for crying out load, would you fix this stupid thing to make it a tiny bit harder to double post (NT)rwessel2013/01/03 12:01 PM
                    /load/loud/ grrr... (NT)rwessel2013/01/03 12:02 PM
                    Oh, for crying out load, would you fix this stupid thing to make it a tiny bit harder to double postDavid Kanter2013/01/10 10:07 AM
                      Oh, for crying out load, would you fix this stupid thing to make it a tiny bit harder to double postrwessel2013/01/10 09:33 PM
                        Oh, for crying out load, would you fix this stupid thing to make it a tiny bit harder to double postrwessel2013/01/10 09:35 PM
                          Oh, for crying out load, would you fix this stupid thing to make it a tiny bit harder to double postrwessel2013/01/10 09:40 PM
                          Me, too! :-)Mark Roulo2013/01/11 08:57 AM
              85 Hz CRT monitorsDoug S2013/01/04 02:12 PM
                85 Hz CRT monitorsAnon2013/01/06 02:16 AM
                  85 Hz CRT monitorsDoug S2013/01/06 12:40 PM
                    The benefits of (non-perceived) flickerMax2013/01/07 01:43 PM
                      The benefits of (non-perceived) flickerAnon2013/01/07 02:59 PM
                        The benefits of (non-perceived) flickerPaul2013/01/07 05:40 PM
                      The benefits of (non-perceived) flickerUngo2013/01/07 03:57 PM
                        The benefits of (non-perceived) flickerDoug S2013/01/07 04:40 PM
                        The benefits of (non-perceived) flickerMax2013/01/07 06:16 PM
                          The benefits of (non-perceived) flickerAnon2013/01/09 09:50 PM
                            The benefits of (non-perceived) flickerMax2013/01/10 06:18 AM
                              The benefits of (non-perceived) flickerSM2013/01/10 12:37 PM
                        The benefits of (non-perceived) flickerdmsc2013/01/07 07:36 PM
                          The benefits of (non-perceived) flickerEBFE2013/01/07 11:08 PM
                          The benefits of (non-perceived) flickerAnon2013/01/09 10:07 PM
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                              The benefits of (non-perceived) flickerUngo2013/01/11 05:20 PM
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        Games at 2048 x 1536? Can you tell?anon2013/01/03 12:54 AM
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            Thanks for the interesting data point! (NT)Paul A. Clayton2013/01/03 09:26 AM
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              The Hobbit is at 48 fpsRichard Cownie2013/01/03 11:55 AM
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                              The Hobbit is at 48 fpsRakesh Malik2013/01/23 12:15 PM
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                      Realism and fiction?Jukka Larja2013/01/06 02:32 AM
                        Or the second factor?Paul A. Clayton2013/01/06 04:35 AM
                          Or the second factor?Jukka Larja2013/01/07 09:07 AM
                        further reading (was: Realism and fiction?)hobold2013/01/06 04:47 PM
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    Lessons in Technology and Innovation from the iPad 3 Graphics and DisplayMegol2013/01/07 04:45 AM
      Lessons in Technology and Innovation from the iPad 3 Graphics and Displaympx2013/01/07 12:56 PM
        Lessons in Technology and Innovation from the iPad 3 Graphics and DisplayDoug S2013/01/07 04:53 PM
        Lessons in Technology and Innovation from the iPad 3 Graphics and Displayanon2013/01/07 06:26 PM
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      Lessons in Technology and Innovation from the iPad 3 Graphics and Displaympx2013/01/07 12:48 PM
      Lessons in Technology and Innovation from the iPad 3 Graphics and DisplayVincent Diepeveen2013/01/08 09:53 AM
        Lessons in Technology and Innovation from the iPad 3 Graphics and DisplayDoug S2013/01/08 01:29 PM
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            Wii U has three cores clocked at about 1.2 ghz or so. (NT)I.S.T.2013/01/29 07:37 PM
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