Grayscale variances - different patterns, plasma calibration - Page 2

You're trashing 2 display technologies that the vast majority of AVS members hold in high regard...

No display is perfect yet, as we all know. Some of us are more irritated by shortcomings in one display over those in another; that's to be expected. You hate ABL; we get that. I hate having people's faces turn lavender when I move 2 feet to the right or left.

Despite that, in certain situations I happen to like both LED LCDs and plasmas. I also feel that the VT50 is the best current consumer display. I also strongly believe that calibrating gamma on plasmas is NOT futile, and JVC D-ILA FP's are great HT PJs.

The optimal gamma calibration for plasma technology will be obtained using fixed average APL stimuli in the 20-40% range (see gory details/measurements here). The GCD disk contains such a pattern sequence for grayscale, gamma and CMS work at 22% fixed APL with 10% windows. These patterns will optimize your plasma calibration over the majority of material you will ever view (excluding hockey).

Steve,


could it be that you talk about high class and high priced LCD-display, which are used mostly as reference monitors in professional studios?

Yeah, I am truly sorry about pointing out the issues with some display technologies, and I agree the viewing angle problem with older TN based LCDs was really carp!

But with IPS now very common there is little real problem, and a good LED backlihg capability is improving that yet further.

We do work with professional display manufacturers, so understand the technologies well.

In my world an ideal set-up is a a very dumb display, with little internal capability (or integrated high-level calibration only) such as the Penta HD2 Line, with external decoder, etc for TV, Blu-Ray, etc, and a LUT box if there is not high-level internal 3D LUT base calibration capability (as there is with the Penta).

However, don't get me wrong, I know a lot of people are very happy with Plasmas and D-ILA projectors.

I have just been too involved in attempting to calibrate them for professional use to know their real capabilities and limitations.

But, that is in a very high-end professional environment where chasing what we call 'Grade One' capability is the goal.

Steve

So the problem is you are applying your proffesional experience to a amateur user market, thereby making statements that do not apply to the people you adress at all.

The intention is okay, but you are making people with perfectly good displays feel bad about them, and setting them up for trying to achieve something that is not within the grasp of the average HG enthousiast. To be blunt, no offense intended, hardly helpfull, is it...

See Zoyd's post #33 above.
I will also say that I have gotten superb results on VT30s from very small conventional windows.

Oh - I thought the people on this forum wanted the best calibration that is possible?

I am only giving my direct experience - you can chose to just ignore it.
Or use it to get the best out of the kit you have, after understanding the limitation and/or issues.

I was asked to join this community by users that were unhappy with the results they were getting.
They asked if I would share my (our) experiences.

As they say, please don't shoot the messenger.

I won't be giving up my 9G Kuros soon, but I'll take a 4200 for my home video editing..

Originally posted here
Specs: http://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/ProMonitor_OverviewSpecsheet_24374_1010_final.pdf

Dolby PRM-4200 - the only grade 1 (unless something was released in the last 3-5 months that slipped by me)

Edited by turbe - 11/27/12 at 2:31pm

no, that will be in the office for just me, this is the lounge for the group....

I haven't had the opportunity to use the GCD on the VT30, but with very small conventional windows I achieved great gamma. Banding on the VT30 is a toughie, esp in low panel brightness mode, which I believe the EU models are stuck in. For some reason (probably different ABL behavior) even after careful calibration the low PB setting can show slight banding on gradient ramps. However, following the guidelines laid out in my custom VT30 CalMAN workflow I have gotten both a great measured gamma curve and a good looking gradient ramp in mid panel brightness.

The reality is that on-board CMS and white balance controls for some consumer plasma displays can achieve excellent results, approaching grade one EBU color metrics for a large cross-section of real world viewing material (example here) For that calibration of the 12 patches I graded, all of them are within 2 error radii of EBU grade 1 , 10 are within 1.5 radii, and 7 of them are within 1 radius. The average error radius = 1.0 and ABL does not affect these results until average stimulus levels exceed about 40% for my particular peak white value of 35 ftL Typical average stimulus levels are well below 40% (hockey excluded).
Edited by zoyd - 11/27/12 at 3:26pm

Have you tried calibrating to the small APL patterns on AVS 709? I know in the 1st post you said you checked them and they gave a different result, but I think using them would be worth a try. I have not tried them on a VT30, but I have tried them on other plasmas with good results. Others have said that they have gotten good results with the large APL windows from the same disc.

This thread is an interesting read: http://www.avsforum.com/t/1412947/plasma-owners-how-do-you-calibrate-saturation
Could someone tell met what EOTF is please?

Hi,

Do you mean the CGD with small AP windowL patterns? I have not seen smal APL window patterns on the AVS709, or did I mis a version?

Sure there are small APL patterns. Choose CalMAN APL and there in the middle row the both most right sided items are small patterns "5 Step Grayscale" and "11 Step Grayscale" and in the row below are the color patterns.

This is at least in version 2D, but I believe in the version which could be downloaded at CalMAN it is the same.

double

Wow, first it posts 4 times with me clicking once to submit, then the actual post with content dissapears.

On the AVS709 disc there are indeed windows with APL. But on the CGD there are really small windows with APL and larger windows with APL, thats what I meant, is that also on the AVS 709 disc, two kinds of windowed APL patterns.

There are two sizes of APL patterns on the AVS 709. Although "small" is relative, I think the smaller one are small enough for me.

Your posting was too small!

Is that true? So.. to calibrate Plasma, we have to use APL windows patterns and set color gamut higher than (D65) target for the screen to be look good in real content? but how much wider(exactly..) w/o over-saturated color ?

The out of the box True Cinema of my Panasonic St50 has gamut very close to D65 reference but somehow I feel like it's undersaturated when watching HD movies, ABL probally is the answer.

and the greyscale of the ST50 OOTB is good ?

ETOF is the new expression for gamma

Thank you jdoostil. What does the acronym stand for exactly then?

Electro-Optical Transfer Function


Search for EBU Document 3325, there is some good info there.

Recommendation ITU-R BT.1886
(03/2011)
Reference electro-optical transfer function for flat panel displays used in HDTV studio production

http://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1886-0-201103-I!!PDF-E.pdf