Tilbudsjagten: Sonos, Apple TV 4K, TCL C845

[sol_jakobsen]

sol_jakobsen: The 970P is not a S-PVA. The same goes for the 193p+.

ups.... yes s-pva is only over "20 i think.... my bad....

[xtknight]

Rasmus, when do you think you'll be able to test that high-contrast LG? Is the LG L203WT one of those high-contrast TN LCDs? Looks like it just uses the LG f-Engine and doesn't actually use a physically different TN panel. The panel is reported to be a CPT (Chunghwa Picture Tubes) TN from what the users can tell in the service menu. However, CPT doesn't have any 20" TN monitor panels ( http://www.cptt.com.tw/english/03_produ ... asp?pid=25 ).

http://www.widescreengamingforum.com/fo ... php?t=3585

Another thing: are we fairly sure now that all PVAs are 6-bit and all S-PVAs are 8-bit? What about MVAs and P-MVAs? You probably know more about this aspect than I.

Thanks

[Rasmus Larsen]

xtknight: I have the LG L1770H review ready for publication. The L1770H utilize LGs new DFC (Digital Fine Contrast) and has a specified contrast ratio of 1600:1.

I do, however, need to make some changes on the server today so I hope to have the review online tomorrow.
The review will contain a small video file. Here you see how the DFC method works. =)

I don't really know about the exact panel. You could be right. CPT doesn’t seem to update their site very often - just like LG.Philips.

Another thing: are we fairly sure now that all PVAs are 6-bit and all S-PVAs are 8-bit? What about MVAs and P-MVAs? You probably know more about this aspect than I.

Not completely sure. It seems like the 6-bit was introduced after the integration of Overdrive. We have an official document from Samsung which specifies the method. The link referred to earlier is not exactly right and Samsung use a more complex method than just 2x2 dithering. First of all they expand to 9-bit in order to get the last shades. If you utilize the ordinary dithering and FRC you will end up with 16.2 million colours instead of 16.7 million colours because you can't reproduce the last few shades in the "dark" end of the grey tone system.

[Simon Baker]

Hi to all. Rasmus, thanks for sorting out my sign up for the forum, and xtknight, thanks for referring me to this thread

I was speaking with xt about this yesterday and my suggestion was that perhaps the older PVA / MVA panels were always 8 bit colour depth (256 shades per sub pixel = 16.7 million colours). Since PVA and MVA panels were always used in more of the "premium" products there was no need to cut costs and so no expense was spared in terms of A/D Convertors and the like. However, now that RTC is being used more and more, the manufacturers seem to be favouring PVA and MVA panels much more. Perhaps in an effort to help keep costs down they are using low performance A/D convertors now and so sadly we are only getting 64 shades per sub pixel, but with dithering being used to produce more colours. It seems logical perhaps...


What do you all think about this 6 bit+FRC in practice though? Does it actually make any noticable difference to colour reproduction in real terms? Could you tell the difference in colour quality / accuracy on a PVA using 6bit + dithering and one using a true 8 bit? Rasmus, do you have any you could compare using your Spider2?

Obviously if there are obvsious dithering artefacts and twinkling noticable then this dithering is not a good thing. However, if this is well controlled and hard to spot, does it really make any difference?


Are any manufacturers actually achieving a true 16.7million colours with dithering processes here, or are they simply misquoting the specs like some TN Film panel manufacturers do? It could be that they are only managing 16.2million colours even on some PVA/MVA panels...

[Torben Rasmussen]

The question about noticable difference in a true 8 bit and 6 bit + FRC and dithering is an unquestionable YES IT IS VISIBLE! I have a 191T and a 193P+ and the color reproduction on the 191T is much more accurate than the 193P+. The dithering is very visible on the 193P+ and twinkling is a problem Samsung should address in future monitors.

When they say that they can produce 16.7 million colors, this is true if we look INDSIDE the monitor. The signalprocessing is done at 9 bit, but as the panel is only addressed by the 6 of these 9 bits (3 bit for FRC) true 24 bit is not the result in the end.

[Simon Baker]

that is a shame, the 193P+ (like you said before) is a lovely looking monitor, it is a shame Samsung have cut corners with it's performance. So aside from thw artefacts, there is also noticable colour reproduction differences? In what areas in paticular? vibrancy? colour range? does it effect black depth at all?

[Torben Rasmussen]

It does not affect contrast, but as the dithering is mostly used in the dark hues, you lose a significant number of colors in the darker regions. You will notice this when you try to reproduce e.g. dark grey as a homogenously colored item will seem to have a twinkling effect (I thought it was pixel boarders when I wrote the review on this page) and if you inspect it closer, you will notice the check-patterned array of darker and brighter dots, trying to trick your eyes into seeing the color you requested.

[xtknight]

On my VP930b (AUO P-MVA), the dithering is extremely hard to notice and only occurs in a very few select tones. There are a couple of tones that are really bad, but just about 2 or 3, so it doesn't bother me. I guess dithering/FRC methods vary widely between panel manufacturers.

On that same German spec site for the VP930, they now list 8-bit when they used to list 6-bit+FRC. Change in marketing or change in electronics?

[Simon Baker]

this dithering can often be more noticable with the application of overdrive as well, and since Samsung seem to be having a tough time controlling the overdrive properly, perhaps that is leading to more of an issue on their panels like the 193P+. It's a shame they haven;t got it sorted out yet, but artefacts, halos, noise in movies are all problems which the latest Samsung models seem to be having sadly.


I notice there was an official reply from Samsung about it, has anyone had any luck with Viewsonic (or more likely AUO) about their P-MVA panels? Do we know whether there is a cut off point where they are using 8 bit rather than 6 bit? Like for instance do Samsung's S-PVA offer anything different?

[Rasmus Larsen]

Rasmus, when do you think you'll be able to test that high-contrast LG?

The review is online now: http://www.flatpanels.dk/l1770h.php

I'm sure it's hard for you to decipher it so I'll summarize the comments about the contrast ratio and DFC. First of all check this video out: http://www.flatpanels.dk/billeder/l1770h_vid1.wmv

It shows how the DFC dynamically changes according to the image on the screen. The backlight is reduced when the mouse is out of the frame. When I move the mouse back the white cursor is recognized and some algorithm must decide to intensify the backlight.

Without DFC I measured the contrast ratio to be 172/0.3 = 573:1. Black dot 0.3 cd/m2

With DFC: 172/0.1 = 1720:1. Black dot 0.1 cd/m2.

The method has potential but it's not perfect yet. If the manufacturers could use LEDs together with this kind of technology we could see interesting results as the backlight could be controlled in sections.

(I read this in a forum) that part of the solution in making the else extremely slow Pva and Mva/p-mva panels fast, was through reduction I collar depth…

That's a quite common fact. The same goes for the TN panels and that's why they have been 6-bit (and fast) for many years. TN panels could just as well be 8-bit panels if the manufacturers decided to do this.
The thing with response time and 6-bit is actually pretty simple. By reducing the panel to 6-bit you generally create 4 steps between each shade. This means that the "distance" between the shades is larger and that the liquid crystals have to twist more.
A larger twist requires a larger voltage and a larger voltage makes the liquid crystals respond faster.

It’s the same method you utilize in Overdrive. Hmm, actually I never thought about it that way. Maybe technical articles about Overdrive could reveal something.

Rasmus, do you have any you could compare using your Spider2?

It's not a Spider2 The Spider2 is a low-cost device and it's not very precise. The hardware I got is made by Gretag which is a very well respected company. My uncle had one of the top positions some years ago and I visited the facility in Switzerland. It's quite amazing really.

Back to the point. No it's very hard to measure. The device does not measure all shades and even if it could it wouldn't reveal anything significant - mostly because dithering and FRC is a "flickering" artefact. If I on the other hand had a response time and flicker device (the one we talked about in the mails) I think I could reveal most of the dithering pretty easily by choosing the right colours to measure from.

I notice there was an official reply from Samsung about it, has anyone had any luck with Viewsonic (or more likely AUO) about their P-MVA panels?

Not that we know of =(

[Simon Baker]

thanks for the reply Rasmus. I was very unsure about it when i was writing, wasn't sure if it was a spider2 or not thanks for clearing it up

that's interesting regarding the DFC, seems to really improve the black spot which is a good thing, especially when you consider all the CRT fans with their "not a deep enough black" arguement Hopefully as DFC improves we will see evern better contrast ratios and a true deep black. I'll check out the video tonight as well when i'm back home. Did you ever test any of the BenQ "SenseEye" products? These had a similar feature accoring to marketing, but not sure if it ever worked in practice. Not seen any of them myself.


I can see the theory behind making panels 6 bit, since you like say, it would suggest that faster response times are achievable, and certainly with TN Film panels traditionally, this was the case. However, under the assumptions above that more gap between shades mean more pixel twisting needed, meaning more voltage needed, meaning faster responsiveness....it might be a little different now that overdrive is widely used. Since the principal of overdrive is really that you are overvolting the pixels (in a very crude sense) to orientate them faster, would it really make any difference if the panel was 6 bit or 8 bit?!

if you are applying the maximum voltage for instance to a pixel which would normally only be used for a full black > white trnasition, you can theoretically greatly improve the response time if the transition needed is only a grey to grey move. In the same way, if the gap between shades is smaller, normally you would only apply a smaller voltage and so response time would be slower. However, with overdrive, this doesnt matter as much as you're applying the higher voltage anyway. Would it not be better if using overdrive that you used 8 bit then so that the gap between shades is less (ie less orientation needed)?! So less gap, but still with the same high voltage = faster response time?!

it's an interesting topic for sure. There might be something in it like you said with regards to overdrive applicaiton. I'll dig through some whitesheets and see if i can find any more information. Would be intersting to hear some feedback from AUO as well, see if i can get any there too

[sol_jakobsen]

an official reply form Viewsonic has ben made on another forum, and it was a yes, they uses 6bit +frc.
They did not answer the question about Dithering thou.............

[sol_jakobsen]

The review is online now: http://www.flatpanels.dk/l1770h.php

I'm sure it's hard for you to decipher it so I'll summarize the comments about the contrast ratio and DFC. First of all check this video out: http://www.flatpanels.dk/billeder/l1770h_vid1.wmv

It shows how the DFC dynamically changes according to the image on the screen. The backlight is reduced when the mouse is out of the frame. When I move the mouse back the white cursor is recognized and some algorithm must decide to intensify the backlight.

Without DFC I measured the contrast ratio to be 172/0.3 = 573:1. Black dot 0.3 cd/m2

With DFC: 172/0.1 = 1720:1. Black dot 0.1 cd/m2.

The method has potential but it's not perfect yet. If the manufacturers could use LEDs together with this kind of technology we could see interesting results as the backlight could be controlled in sections.

This â€

[Torben Rasmussen]

Yes it is not quite the same. MagicTune is just a software part to control the monitor and does not control the monitor in-situ as the image changes. DFC analyze what is on the screen and adjusts the backlight accordingly.