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Calibration problems

post #1 of 17
Thread Starter 
Hi,
I've been trying to properly calibrate my TV (Panasonic TX-P50UT50E) with my new bought Colormunki Display for some time now (few days), but it starts to get really frustrating.
First off, here's what I have accomplished so far:




I used the AVS HD 709 HDMV disc, with APL Large for the gray scale and APL small for the colors.

Now here is the greyscale with windows (and 20pt) instead of APL:


I really don't get what's going on here. How can there be such a huge difference between ~15% windows and 8% APL? Which one should I trust? I've heard that the ABL of the TV kicks in pretty early, but I don't really know how to use that information. Does that speak for the APL or the windows?

What's more is that, as you can see on both greyscales, blue behaves radically different at 5/10% than at (20)/30%. That's the reason I am having too much blue at 30%, if I alter the cutoff setting for blue only slightly, the 10% gray goes down almost 10%.
I have tried adjusting red and green instead of blue in the hopes, that I'll get better results, but that didn't work out.
Something similarly is going on with red, but the other way around. 5% grey, looks ridiculous, it's almost just a dark red.

I've been playing around a little and don't have all the graphs saved, but red and blue both look like a sin/-sin curve, where 0 is at about 25%, if that makes any sense.

If anyone has suggestions as to what to try next, i'd would be very grateful.
post #2 of 17
Greetings

You should give this article a read as it might give you a better perspective on what you are trying to accomplish.

regards
post #3 of 17
Thread Starter 
Thanks, are you getting at the "WAG" or the insignificant differences pointed out in this article? As far as the guessing goes, I think most peoples guess will be better than mine, as it may be at least a little bit informed. As far as the differences between the methods go, they are huge in my case, as you can see.
post #4 of 17
Greetings

The WAG is that since no one can relate their viewing habits to a specific test pattern, it becomes a game of cherry picking your results to get a pretty graph ... with no correlation to the calibrated state actually being better.

Don't forget the inherent error that is built into the meter you are using. It can be like trying to achieve some level of perfection using a yard stick that really is 38" rather than 36" ... be as careful as you want, but the yard stick is still what it is.

regards
post #5 of 17
Quote:
Originally Posted by monvo View Post



If anyone has suggestions as to what to try next, i'd would be very grateful.

The differences between those two grayscale plots is larger than what I would expect for a windows vs. APL comparison, so maybe something else changed in between. I would sort that problem out first since for grayscale it really shouldn't matter if you use a 10% window or the AVSHD large or small APL. Re-run in sequence a 10 pt. grayscale using 10% windows followed by one of the AVSHD APL (or both) and compare. Often times when starting out it's easy to change too much stuff at once and then end up wondering why the results are different.

It also looks like your contrast is set too high, that will cause the RGB channels to separate at the higher levels in your gamma graph.
Edited by zoyd - 6/14/13 at 7:28am
post #6 of 17
Thread Starter 
There seems to be a problem with my TV and the large APL patterns. The small APL and window patterns look about the same.

I don't know how to calibrate the colors yet though. Between the APL small and window patterns the the Y values for the colors themselves are identical, but the Y value for the reference measure of white changes drastically (a lot higher in the apl pattern). So one pattern tells me the luminance of the colors is way to high, while the other tells me it's great. I have now used the APL small pattern for the calibration of the colors, because I guess the ABL kills the white with the windows, but not the colors. The problem is, that there are no saturation patterns on the disc for APL small.

Additionally I'm using a spectral sample now, when I hadn't before. It basically just corrected for red. Current measures, after some tweaking:





Every tip is much appreciated!
Edited by monvo - 6/14/13 at 11:02am
post #7 of 17
Quote:
Originally Posted by monvo View Post

There seems to be a problem with my TV and the large APL patterns. The small APL and window patterns look about the same.

I don't know how to calibrate the colors yet though. Between the APL small and window patterns the the Y values for the colors themselves are identical, but the Y value for the reference measure of white changes drastically (a lot higher in the apl pattern). So one pattern tells me the luminance of the colors is way to high, while the other tells me it's great. I have now used the APL small pattern for the calibration of the colors, because I guess the ABL kills the white with the windows, but not the colors. The problem is, that there are no saturation patterns on the disc for APL small.

Additionally I'm using a spectral sample now, when I hadn't before. It basically just corrected for red. Current measures, after some tweaking:





Every tip is much appreciated!

Do you have a plasma? If so, use small APL or non-APL windows.
post #8 of 17
What is your peak white using small APL and using 10% windows? Also, post your primary/secondary measures showing dE, delta luma etc. for the two types of patterns.
post #9 of 17
Thread Starter 
Peak White APL small: Y=120 (35ftl)
Peak White windows (the AVS 709 ones): Y=105.5 (30,8ftL)
Unfortunately I only have the APL small primaries and secondaries at the moment, because I have to remeasure for the window ones (I had to put them in Excel because I can't figure out how to change window sizes inside HCFR):

If I recall correctly everything stays the same when I use windows, except for the Y values, where I get a big error, because peak white is lower.



Maybe it's easier just to give you the HCFR report:
calibration report.zip 1k .zip file
post #10 of 17
Quote:
Originally Posted by monvo View Post

Peak White APL small: Y=120 (35ftl)

If I recall correctly everything stays the same when I use windows, except for the Y values, where I get a big error, because peak white is lower.

So yes, ABL is not allowing you to use the AVSHD windows which I think are around 15%. Stick with the small APL or you could use the 10% windows from the GCD disk or even smaller from Mascior's disk. You will find though the differences are not as large as what you were seeing with ABL active. So just pick one set and stick with it, either smaller sized windows or small APL type, you'll get a good calibration either way. You should also calibrate color at 75% stimulus which gives you around 50% peak luminance (for a good mid-point in gamut luminance).
post #11 of 17
@Monvo

Use the Plasma Spectral by itself (do not add any correction file) in the HCFR drop down list to use with the munki and try Masciors 4% standard or 4% apl pattern windows.

I have a Panasonic GT30 and those patterns seem to work best on my set (I liked the 4% standard the best)..
post #12 of 17
Quote:
Originally Posted by PeterLewis View Post

I have a Panasonic GT30 and those patterns seem to work best on my set (I liked the 4% standard the best)..

Is it better to use smaller windows with the more aggressive the ABL or the other way around? I have an S60 2013 set which people have said has a more aggressive than most ABL circuitry and was wondering this. I have always just calibrated using the standard AVS HD709 window patterns which are 14% or 15%

I think I had seen a calibrator mention how using APL patterns or smaller patterns to bypass the ABL is not a good idea...
post #13 of 17
Quote:
Originally Posted by fairchild99 View Post

Is it better to use smaller windows with the more aggressive the ABL or the other way around? I have an S60 2013 set which people have said has a more aggressive than most ABL circuitry and was wondering this. I have always just calibrated using the standard AVS HD709 window patterns which are 14% or 15%

I think I had seen a calibrator mention how using APL patterns or smaller patterns to bypass the ABL is not a good idea...

I've searched threads,post's and tried just about every pattern size under the sun to calibrate THX mode on my set (Panny GT30) before I found a post by D-Nice over at HDJ in the GT30 thread and 2011 Fl & Brightness thread and he mentioned that he and a Pioneer engineer were talking and that he mentioned that THX used a 4% pattern to pass specs on the 2011 Panny sets.

Here is one his quotes...Read the last line.

"Also, I have figured out how David @ HDTVTest.com got 2.2.... its all in the windowed pattern size. Using the small APL windowed patterns on the AVS709 disc, I easily got 2.2 in THX, Cinema and Custom mode (Gamma setting of 2.2 in Custom). However, using my Accupel 4000... which actually has the standard windowed pattern sizes... I get 1.9. My take on this is Panasonic is using small windowed patterns (around the 4% size) to get this displays THX certified as THX uses similar sized windowed patterns. Not sure who approved this, but it is flat out wrong."

So if THX engineers used 4% patterns to pass specs on my tv set,it only makes more sense to use those said patterns...
post #14 of 17
Cherry picking a pattern to pass a spec is thinking about the problem backwards. All it does is create a pretty graph and ignores the problem of variable APL gamma.
post #15 of 17
Quote:
Originally Posted by PeterLewis View Post

"Also, I have figured out how David @ HDTVTest.com got 2.2.... its all in the windowed pattern size. Using the small APL windowed patterns on the AVS709 disc, I easily got 2.2 in THX, Cinema and Custom mode (Gamma setting of 2.2 in Custom). However, using my Accupel 4000... which actually has the standard windowed pattern sizes... I get 1.9. My take on this is Panasonic is using small windowed patterns (around the 4% size) to get this displays THX certified as THX uses similar sized windowed patterns. Not sure who approved this, but it is flat out wrong."

So if THX engineers used 4% patterns to pass specs on my tv set,it only makes more sense to use those said patterns...

The way I interpret that quote is that D-nice is basically saying it's wrong to use the smaller 4% pattern to achieve the certification, he even says it is flat out wrong... He did say using APL small pattern he gets 2.2 but using his signal generator which uses larger windows (maybe 10-15%) the gamma reading is 1.9
Quote:
Originally Posted by zoyd View Post

Cherry picking a pattern to pass a spec is thinking about the problem backwards. All it does is create a pretty graph and ignores the problem of variable APL gamma.

So Zoyd, I've followed your posts and the calibration forum in general, I still am not sure what should produce the best and most accurate calibration for my S60 which has an aggressive ABL (whether it's actually more aggressive than other panels this year I don't know). I have attained thus far a good looking image and the charts are not bad given that I only have 2-pt to deal with and half of a CMS using the AVS HD709 window patterns + HCFR. Should I try calibrating with say 10% APL constant patterns such as the GCD or Mascior disc, or should smaller patterns be used?
post #16 of 17
Quote:
Originally Posted by fairchild99 View Post


So Zoyd, I've followed your posts and the calibration forum in general, I still am not sure what should produce the best and most accurate calibration for my S60 which has an aggressive ABL (whether it's actually more aggressive than other panels this year I don't know). I have attained thus far a good looking image and the charts are not bad given that I only have 2-pt to deal with and half of a CMS using the AVS HD709 window patterns + HCFR. Should I try calibrating with say 10% APL constant patterns such as the GCD or Mascior disc, or should smaller patterns be used?

For grayscale and color calibration pattern geometry is just not a significant variable for plasmas as long as you keep the loading under a reasonable level, say the equivalent of 20% area windows.

With gamma, pattern size does make a visible difference but it's still not huge, it's hard to find examples of more than a 0.1 shift. Add to that the fact that your gamma target is squishy depending on environment and some range of preference, there isn't one answer.

So let's say you pick your dream gamma function and you just have to know if your set reproduces it faithfully to 2 decimal places, let's say you want a perfectly flat 2.20 at all stimulus levels. The only way to know if your TV reproduces this function is to measure it at all APL levels or at least a range covering the loading levels you believe are most important. This would require multiple sets of patterns each holding the load on the plasma at a known luminance level. Let's say the typical operating range of your plasma produces average luminance levels between 5% and 20%. Suppose you obtain the following measurements:

1. APL set 1: 5% luminance loading, gamma = 2.0
2. APL set 2: 10 % luminance loading, gamma=2.1
3. APL set 3: 15% luminance loading, gamma=2.2
4. APL set 4: 20% luminance loading, gamma=2.3

The average response over your range is 2.15 so you would increase gamma a notch until the average reached 2.2. Now I don't think anyone wants to go through the trouble of 4 (or more) sets of measurements so I would recommend using either Mascior 4% APL patterns, which are in the middle of the above range, or the GCD 22% constant stimulus which cover the lower half of that range. Or you could just have another beer and watch a movie.
post #17 of 17
Quote:
Originally Posted by zoyd View Post

With gamma, pattern size does make a visible difference but it's still not huge, it's hard to find examples of more than a 0.1 shift. Add to that the fact that your gamma target is squishy depending on environment and some range of preference, there isn't one answer.

The average response over your range is 2.15 so you would increase gamma a notch until the average reached 2.2. Now I don't think anyone wants to go through the trouble of 4 (or more) sets of measurements so I would recommend using either Mascior 4% APL patterns, which are in the middle of the above range, or the GCD 22% constant stimulus which cover the lower half of that range. Or you could just have another beer and watch a movie.

Since my set doesn't even have fine-tune adjustments for gamma, trying to hit a gamma point is often an attempt at futility. I can only adjust the gamma range from 1.9 to 2.6 and then depending on patterns, the gamma will differ wildly I've noticed.

I guess I'll just have me another shot of JD, since I'm not that into beer. Thanks!
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