Adjusting Cell Light on a Plasma - AVS Forum
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post #1 of 49 Old 02-21-2013, 11:11 AM - Thread Starter
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I have the WOW and Spears and Munsil setup discs. They explain how to tweak brightness and contrast, but neither explains how to work the Cell Light control into the mix. I'm trying to maximize black level in my new Samsung E7000.
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post #2 of 49 Old 02-21-2013, 11:31 AM
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Cell light need to be set at 100% if you don't you will create all sort of problems inside the gamut, just try to do a search on here
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post #3 of 49 Old 02-21-2013, 12:09 PM
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Quote:
Originally Posted by ed3120 View Post

I have the WOW and Spears and Munsil setup discs. They explain how to tweak brightness and contrast, but neither explains how to work the Cell Light control into the mix. I'm trying to maximize black level in my new Samsung E7000.

In the D7000/8000 settings thread (I think), it was mentioned that a Samsung engineer had said to set and forget it at maximum (20). Apparently the control is only there because consumers expect it since LCDs have a 'light' setting (backlight).

Adjusting settings according to personal preference is not
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post #4 of 49 Old 02-22-2013, 10:28 AM
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The max setting is the optimal setting for Cell Light .
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post #5 of 49 Old 03-29-2013, 06:19 PM
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Why would cnet use a setting of 14 on one of them? Is there 1 advantage to setting it lower?
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post #6 of 49 Old 03-29-2013, 07:06 PM
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Originally Posted by Vic12345 View Post

Why would cnet use a setting of 14 on one of them? Is there 1 advantage to setting it lower?

On the Samsung D series the 10 point intervals shift and become trickier to adjust at low contrast settings. If you keep contrast at a high setting in order to make calibration easier, you can reduce light output with the cell light control instead.

Adjusting settings according to personal preference is not
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post #7 of 49 Old 03-29-2013, 09:26 PM
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My gamma is continuously changing with no meter here.after lowering it to 17 It seems like it balanced the varying types of screen gammas (aka abl).id rather have my tv a bit darker and more balanced then large gamma changes.. If anyone has any Other suggestions to balance gamma(no meter here)you get a Thankyou . smile.gif and I only have 2point grayscale.

in order to keep the white patches from being too bright Ive used contrast 63,cell 20.most people use contrast settings in 80s n 90s.

Is it better to lower cell light or lower contrast too have the abl/gamma more consistent/stable?
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post #8 of 49 Old 03-30-2013, 05:19 PM
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Originally Posted by Vic12345 View Post

My gamma is continuously changing with no meter here.after lowering it to 17 It seems like it balanced the varying types of screen gammas (aka abl).id rather have my tv a bit darker and more balanced then large gamma changes.. If anyone has any Other suggestions to balance gamma(no meter here)you get a Thankyou . smile.gif and I only have 2point grayscale.

in order to keep the white patches from being too bright Ive used contrast 63,cell 20.most people use contrast settings in 80s n 90s.

Is it better to lower cell light or lower contrast too have the abl/gamma more consistent/stable?

That value for contrast is much too low I would have it higher but set your Cell Light to 20 and leave it there. Control the light output with contrast but I wouldn't go as low as you did. Adjust using a white clip pattern , rules for setting contrast properly.

No Eye fatigue, no discoloration/pinking and no clipping. Set it so it meets these rules. AVS HD 709 disk has the pattern you need.
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post #9 of 49 Old 03-31-2013, 09:54 PM
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Quote:
Originally Posted by Vic12345 View Post

Why would cnet use a setting of 14 on one of them? Is there 1 advantage to setting it lower?


Because you don't have to know what you are doing to review video displays... anybody can write whatever they want to write on the internet and post it. Doesn't have to be accurate or researched. The internet cops don't pull you over for posting something that's not right.

There is 1 reason Cell Light even exists as a "control" on plasma TVs... because LCD TVs have a Backlight control. Cell Light lets Samsung use the same menu structure for LCD and plasma TVs... just change the name of that "slot" from Backlight to Cell Light on plasmas. Before Cell Light existed as a control, all Samsung plasmas were manufactured and operated as though the Cell Light control was set to it's highest setting. Once the Cell Light control was added, the only "correct" setting for Cell Light was the highest available setting. When I reviewed my first Samsung plasma TV that had a Cell Light control, the contact person Samsung provided to answer technical questions for the review explained the control did nothing useful, set it to the maximum setting and leave it there. It's only purpose is to fill the slot in the TV's menu structure left by the Backlight setting. It is a "made up" control with no value... other than to give Samsung plasma TVs something no other plasma TVs have (because it doesn't do anything useful, no other plasma manufacturer ever bothered to include such a control). In the first year the cell light control appeared, using lower settings really mangled gamma. That seems to have been tuned out over 1 or 2 years following the initial appearance of the control, but it still does not do anything useful and it should be set to the highest setting and left there. Ignore that it even exists and you'll be fine.

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post #10 of 49 Old 04-01-2013, 10:23 AM
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Originally Posted by Doug Blackburn View Post

Because you don't have to know what you are doing to review video displays... anybody can write whatever they want to write on the internet and post it. Doesn't have to be accurate or researched. The internet cops don't pull you over for posting something that's not right.

There is 1 reason Cell Light even exists as a "control" on plasma TVs... because LCD TVs have a Backlight control. Cell Light lets Samsung use the same menu structure for LCD and plasma TVs... just change the name of that "slot" from Backlight to Cell Light on plasmas. Before Cell Light existed as a control, all Samsung plasmas were manufactured and operated as though the Cell Light control was set to it's highest setting. Once the Cell Light control was added, the only "correct" setting for Cell Light was the highest available setting. When I reviewed my first Samsung plasma TV that had a Cell Light control, the contact person Samsung provided to answer technical questions for the review explained the control did nothing useful, set it to the maximum setting and leave it there. It's only purpose is to fill the slot in the TV's menu structure left by the Backlight setting. It is a "made up" control with no value... other than to give Samsung plasma TVs something no other plasma TVs have (because it doesn't do anything useful, no other plasma manufacturer ever bothered to include such a control). In the first year the cell light control appeared, using lower settings really mangled gamma. That seems to have been tuned out over 1 or 2 years following the initial appearance of the control, but it still does not do anything useful and it should be set to the highest setting and left there. Ignore that it even exists and you'll be fine.

why didn't they just make it a placebo control (you can adjust it from 0-20 but it's internally fixed at 20 regardless of what value you choose in the user menu)?


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post #11 of 49 Old 04-12-2013, 05:07 AM
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At least with PS64E8000 (FW 2006) you can get less agressive 10-point gamma tracking with lower cell light and higher contrast if your peak white target is 120cd/m2
That affects to readings of ANSI but if difference is small and overall performance is better with lower cell light...however I decided to go back with lower cell light and higher contrast.
Maby it´s different with F8500.

i1Display Pro
cell light / contrast (measures from center of HCFR contrast ANSI pattern 50% APL, all with same peak white 120cd/m2 from window)
13 / 98 = 78.6cd/m2
20 / 83 = ~83cd/m2
16 / 95 = 75.8cd/m2
MLL
FIELD (with pause icon) 0.018cd/m2
ANSI 0.025-0.027cd/m2

First measure 13/98 was almost right after out of box, I wonder why it gives better ANSI white Y than 16/95
I´ll re-check that at next calibration and go back to 13/98 if that really give better ANSI and much easier gamma tracking than 20/85
Now I´m with 16/95

btw, is Samsungs´s cell light same as panel luminance setting with 2013 Panasonic plasmas?
http://www.hdtvtest.co.uk/news/panasonic-tx-p50gt60-201304052795.htm
"[Advanced Settings] features a [Panel Luminance Setting] which we asked for last year, but now find no reason to touch (irony?) because the basic [Contrast] control alone is enough to produce a very deep, bright picture. The [Panel Luminance Setting] works largely by adjusting the output gamma, rather than proportionally making the image brighter."

Q: David, what´s ANSI white reading with max contrast?
Did you try set [Panel Luminance Setting] to "mid" or "high" and lower [Contrast] setting to get 120cd/m2, is there difference with ANSI white?

A: I left Panel Luminance on low to get the flattest base gamma tracking: as I often say, hammering away at the 10 point controls to get flat gamma should be avoided because it'll only be truly flat with one APL.


If that´s the case also with Samsung´s cell light control then it explains differences with gamma settings with same peak light output.
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post #12 of 49 Old 04-13-2013, 12:29 AM
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What the HECK is "less aggressive gamma tracking"???? You are making things up.

With 10-point gamma controls you have full control over the luminance of each grayscale step. That means you have FULL CONTROL over your gamma curve using the 10 point grayscale controls. If any step is not following your desired 2.25 gamma (determined by measuring 100% white first and letting the software determine the luminance of 90, 80, 70, etc.), you simply adjust the luminance of that step so it follows your selected gamma curve. If any step is too dim, you simply raise the three RGB controls for that step. If any step is too bright, you simply lower the three RGB controls for that step.

You do NOT tweak gamma by using the Cell Light control which... (why this is so difficult to understand, I'll never know) the MANUFACTUTER'S technical spokesperson said is not a control that is useful for anything -- Cell Light only exists to allow Samsung to maintain identical menu structures for LCD and plasma TVs.

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post #13 of 49 Old 04-13-2013, 02:42 PM
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What make73 means is, that with for example Cell20/Contr. 83 (from his above post) the points from the 10p. WB don't correspond with the actual IRE's like on a higher contrast setting. The points are shifted. This is maybe not the case on all models or firmwares, but mentioned a lot. Cellight does not have this effect on the 10p. controls.
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post #14 of 49 Old 04-13-2013, 04:43 PM
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Leave Cell Light at Max in your case 20 . The ABL is less aggressive and you get the max light output on a full field white. I think this is the explenation. Doug has mentioned why the control is there and that it's best to leave it at Max. Then use your contrast to adjust the peak light output. Oh I see, the points get shifted because you have contrast too low. Try lower 90's that should re-align the points.

Remember the rules of contrast, no pinking or discoloration, no clipping and no eye strain then your good to go . Use a white clipping pattern. When you had contrast at 98 for the one example that is already to high and you are pinking. For the samsung d series it is best to keep contrast at 95 or below but not lower then 90 let's say to keep the 10pt aligned. Having a lower contrast can be done but then you need to play around with a grey ramp to see where the 10pt shifted too. I think it's more trouble then it's worth in my opinion , more frustration in the equation.
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post #15 of 49 Old 04-13-2013, 10:41 PM
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Originally Posted by Doug Blackburn View Post

What the HECK is "less aggressive gamma tracking"???? You are making things up.
Maby David´s "hammering" is better term smile.gif
I´m just DIY rookie calibrator so sorry if I mix things redface.gif

Just noticed with my´n set that you get flatten base gamma with lower cell light and higher contrast settings, and because gamma seems to change depending what kind of APL patterns to use then if hammered it with 10-point to track with one APL it don´t serve with other...well however that´s just too frustrating for me. If there´s one and only correct APL pattern for calibration that model I would be glad to hear that smile.gif
I´m good to go with AVS HD APL patterns (small windows) and happy with them, at least it looks good by eyes.
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Remember the rules of contrast, no pinking or discoloration, no clipping and no eye strain then your good to go . Use a white clipping pattern. When you had contrast at 98 for the one example that is already to high and you are pinking. For the samsung d series it is best to keep contrast at 95 or below but not lower then 90 let's say to keep the 10pt aligned. Having a lower contrast can be done but then you need to play around with a grey ramp to see where the 10pt shifted too. I think it's more trouble then it's worth in my opinion , more frustration in the equation.
Thanks hungro, pinking is totally new term for me, any link for explanation?
Sure I always measure near white for no clipping any white levels.
Bolded text from your answer seems to be the whole case why use lower Cell Light value, if your peak white target is 35ftL / 120cd/m2 it´s must to lower Cell Light at least with PS64E8000 with latest FW to keep contrast with higher level because of less hammering 10-point wink.gif
Quote:
Originally Posted by Doug Blackburn View Post

You do NOT tweak gamma by using the Cell Light control which... (why this is so difficult to understand, I'll never know) the MANUFACTUTER'S technical spokesperson said is not a control that is useful for anything -- Cell Light only exists to allow Samsung to maintain identical menu structures for LCD and plasma TVs.
Thanks for info, yes read before that one person from Samsung told that.
Earlier also with PS64E8000 peak white with Movie mode was limited to something like 31.8ftL / 109cd/m2 but not anymore, maby Samsung didn´t examine enough how it affects to performance when they released new FW which removed limit and now you can get 50.4ftL / 170cd/m2 with same Movie mode.
Somehow it´s hard to believe it´s just and only control over contrast because why it cause behavior like this. If results would be same with same light output if you use e.g. 20 / 83 or 16 / 95 then I would accept that.
And yes, now I know behavior is totally different than with 2013 Panasonic´s Panel Luminance Setting.

Screen fit (disabled overscan) for external 720p signal (cable receiver) is working but with internal dvb-c tuner with same 720p signal that´s not working(option is grayed), "That´s not fault but feature" said also person from Samsung to me rolleyes.gif
I wonder why they don´t let us disable overscan also with SD-material like you can do with Panasonic models.


Here is newest measurements and settings (comments are however mostly in finnish smile.gif)
Open with latest build of HCFR
Samsung PS64E8000 calibration.zip 146k .zip file
"Samsung PS64E8005 130h 2D Movie calibrated with GCD Disk APL Pana1 matrix.chc" show with GCD disk adjusted Primaries and Secondaries dE´s wrong because used AVS HD after that
"Samsung PS64E8005 135h 2D Movie calibrated with AVS HD Disk APL Pana1 matrix.chc" is mode which I use most.

btw, One thing you should notice is (at least with European models) Samsung´s ABL behavior and someones have report that using lower Cell Light is also somekind of cure to that. I assume it´s same case with E8000 than E6500, don´t have Klein K10-A to measure that.
http://www.hdtvtest.co.uk/news/samsung-ps60e6500-ps51e6500-201207262022.htm?page=Performance
Attached Files
File Type: zip Samsung PS64E8000 calibration.zip (145.9 KB, 27 views)
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post #16 of 49 Old 04-14-2013, 04:10 AM
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Here is newest measurements and settings (comments are however mostly in finnish smile.gif)

I noticed the calibration with GCD APL is showing an abnormally high 0% reading of 0.09 cd/m^2, others are around 0.02 cd/m^2 which is more typical of the E series. That in turn skews the BT.1886 target to lift luminances in the 10-20% range too much. You should check that reading, those patterns might increase the mll to about 0.04 cd/m^2 but not 0.09. You might want to try the 4% APL set on mascior's disk, they work very well on my D series.

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post #17 of 49 Old 04-14-2013, 05:05 AM
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I noticed the calibration with GCD APL is showing an abnormally high 0% reading of 0.09 cd/m^2, others are around 0.02 cd/m^2 which is more typical of the E series. That in turn skews the BT.1886 target to lift luminances in the 10-20% range too much. You should check that reading, those patterns might increase the mll to about 0.04 cd/m^2 but not 0.09. You might want to try the 4% APL set on mascior's disk, they work very well on my D series.

That´s true, and really because of tracking BT.1886 gamma
Un-checking "Use round down levels" with GCD made things just wierd compared to AVSHD709 disk with same setting enabled. How that option actually affect? Earlier I measured with both disk´s that option enabled and got almost same results.
Using two different disk´s was frustrating and I gave up. You can notice from same file that ANSI black was 0.024cd/m2 without tweaking anything between those measurements and I don´t know where that MLL/black disappeard from Contrast measurement confused.gif

Maby I´ll try that mascior´s disc with 4% APL since there´s also AVCHD version wink.gif
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post #18 of 49 Old 04-14-2013, 05:46 AM
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Originally Posted by Make73 View Post

That´s true, and really because of BT.1886 gamma
Un-checking "Use round down levels" with GCD made things just wierd compared to AVSHD709 disk with same setting enabled. How that option actually affect?
Using two different disk´s was frustrating and I gave up. You can notice from same file that ANSI black was 0.024cd/m2 without tweaking between those measurements. I don´t know where that MLL measurement disappeard from Contrast measure with that same file confused.gif

Maby I´ll try that mascior´s disc with 4% APL when he release AVCHD version, I don´t have BD-R device.

The round-down checkbox changes the percentages used in the calculations. AVSHD rounds fractional RGB codes down to the nearest integer while GCD rounds in the normal fashion. HCFR will use the exact % stimulus based on that check box, note that if you mouse over one of the graphs at the 10% stimulus level it's actually 10.04570%:GCD, 9.58904%:AVSHD This difference will have minor effects on the gamma values but best to not mix disks in the same file runs. I would be interested in what you measure for the E-series mll vs. APL, there is a test disk here for that.

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post #19 of 49 Old 04-14-2013, 06:14 AM
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I would be interested in what you measure for the E-series mll vs. APL, there is a test disk here for that.

I´ll try to do measurements ASAP.
I can only give you numeric values to here, since I´m not so good to doing diagrams smile.gif

edit:
Measured cd/m2 Y-values with Your disc and also checked calibration with Masciolas disc.

Seems that at least magenta is different than with AVS HD 709. For saturation 0% measured also with 25%S pattern.

When "Use round down levels" was checked grayscale/gamma was almost same as with AVS HD 709, however made measures with un-checked.That makes me think if that setting work properly for AVS HD APL small windows? (Oh, seems that it update results also afterward if it´s checked or unchecked and restart HCFR)

4x4 ANSI is measured by hand, was too tired to set up tripod to every position smile.gif

You did some hardware tweaking for MLL with your D-serie?
Did you measure with same disk without tweaking?
My results are not so good with higher APL-levels, is that only Samsung´s problem?

Samsung PS64E8000.zip 22k .zip file
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File Type: zip Samsung PS64E8000.zip (21.7 KB, 24 views)
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post #20 of 49 Old 04-15-2013, 07:29 PM
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Originally Posted by Make73 View Post

Maby David´s "hammering" is better term smile.gif
I´m just DIY rookie calibrator so sorry if I mix things redface.gif

Just noticed with my´n set that you get flatten base gamma with lower cell light and higher contrast settings, and because gamma seems to change depending what kind of APL patterns to use then if hammered it with 10-point to track with one APL it don´t serve with other...well however that´s just too frustrating for me. If there´s one and only correct APL pattern for calibration that model I would be glad to hear that smile.gif
I´m good to go with AVS HD APL patterns (small windows) and happy with them, at least it looks good by eyes.
[\quote]

This makes it sound like you still do not understand gamma and that you did not understand my explanation of how you control gamma with the 10-point gamma controls. Until you understand the information in the earlier message, you will NOT understand gamma.

Everything you are saying here sounds confused... perhaps it is the language difference and I don't understand what you are trying to say.

Let me try again with different words.

To start the calibration, pick the mode you want to calibrate (like Movie mode). Set the black level with the Brightness control. Set the luminance level for 100% white to a good setting with the Contrast control. Let's say you pick 100 cd/m2 for 100% white. When you use the 10-point grayscale controls to make the 100% step accurate, any red, green, or blue control you adjust to a higher setting will raise the 100 cd/m2 so you might have to lower the 100% controls a little bit to get 100% white set to 100 cd/m2 again (or if 100% gets darker when you are adjusting the 100% step, you may have to increase the red, green, and blue controls so you have 100 cd/m2 again. You MUST do the 100% step first because this measurement is what determines the luminance/brightness of all the other steps (10%-90%).

When you have 10-point gamma controls, you have complete control over gamma. You must pick ONE mode to calibrate. Set the Cell Light control to the highest setting and LEAVE IT ALONE... FORGET IT EXISTS. I am telling you that the manufacturer added this "control" for no good reason. You MUST stop obsessing about it or you will never understand how your TV works. Use small window patterns for 10%-100% white and colors to minimize brightness limiting. You cannot stop brightness limiting so some of it must be included in your calibration or the images will not look right, People who think you should eliminate brightness limiting with patterns with variable sizes will not be compensating for the brightness limiting in the final calibration. So just use small window patterns (around 10% of the area of the screen). And focus on your adjustments of the 10-point controls to make gamma perfect. Pick a good number for gamma in your calibration software. I use 2.25 because the studios who do the mastering have their workstations setup to show 2.2 or 2.3 gamma. 2.25 is the best compromise "goal" for home video displays. The 10-point grayscale controls do 2 things for you... #1 I think you understand... they remove any color tint for each step from 10% to 100%. #2 is that those controls give you control of luminance/brightness for every grayscale step. If the gamma for the 20% step is too high (the number is too high, maybe 2.5, for example) that means the 20% step is too dark. To make the 20% step brighter, you increase all 3 controls for the 20% step... you have a red control, a green control, and a blue control. These controls determine how bright each color is... it you set the red control higher, red gets brighter. If you set the blue control lower, blue gets darker. When you adjust red, green, and blue higher (all 3 colors at the same time), you make the 20% grayscale step brighter so the gamma number comes down below 2.5 and you can get it to be 2.25 without very much trouble... just a few measurements will make the 20% step right.

When you finish making the xy (color) and the Y of every step (according to the gamma goal you enter in the calibration software) correct, measure the grayscale again. There may be some small errors that require some changes. If you have to change 100% white for any reason, you will have to re-calibrate ALL the grayscale steos again for xy (color) and Y (gamma/luminance/brightness). You may have to fine-tune the grayscale 2 or 3 times to get all the color and luminance settings accurate. That is normal, but some TVs will look good after 1 adjustment of the grayscale... Samsung TVs often only need 1 accurate grayscale/gamma calibration. But remember... if you change 100% luminance, your gamma will need to be adjusted again for every grayscale step. That's why it is important to keep the 100% measurement accurate (100 cd/m2 or whatever you want your reference brightness number to be) while you are calibrating... the gamma for the whole grayscale is based on numbers calculated from the 100% measurement. All these other things you are trying to do to change gamma are not correct. Your 10-point grayscale controls are your gamma adjustments AND your adjustments to remove any colors from the grayscale steps.

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post #21 of 49 Old 04-15-2013, 08:34 PM
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Thanks a lot for your professional help, I really appreciate that smile.gif

However seems that you don´t want to hear anything over that what you heard from Samsung, did you followed links what I gave?
You don´t agree that Cell Light setting has anything to do like with brightness pops (ABL behavior)?
Have you noticed same as like me and "hungro" did, when you lower contrast under 90 (if Cell Light is 20 I have to set Contrast to 83 for 120cd/m2 peak white) it behaves strange and you have to adjust (display/power) gamma with 10-point too much and that´s not good thing because it´s fully linear only with one kind of patterns.

Maby I should stay just with basic things, that´s why I´m asking things like which APL pattern is best for Samsung plasmas.
AVS HD´s APL small windows and Mascior´s 4% APL patterns seems to give almost same kind of results.
At next time, when Masciolas release rev 4 version of disc I´m going to do color calibration with 4% APL 75%A 75%S patterns to get more accurate 50%&75% saturation. Now it´s oversaturated.
Earlier tried to do grayscale and gamma with AVS HD and 75% colors with GCD and that was too confusing. zoyd´s advice to stay with one disk at one calibrations seems to be reasonable smile.gif

Yes, my´n english is not so good and there´s still lot´s of confusing terms (I´m learning all the time, credits goes to all helpfull guys from many different forums and sure I started few years ago with Greyscale & colour calibration for dummies smile.gif) but still you don´t have to start tell everything from at very beginning.

btw, With PN60F8500 calibration by Kevin Miller he didn´t set backlight to 20 except for CalDay
Here is basic settings for CalNight:
Picture Mode: CalNight
Color Temp: Warm 2
Gamma: 2
Backlight: 13
Brightness: 47
Contrast: 95
Color: 50
Tint: G50/R50
Sharpness: 0


zoyd,
Did you watch those measurements which you requested?
I wonder why 4x4 ANSI patterns gave those MLL readings while MLL with your test with higher APL´s was so high? What´s APL with that 4x4 ANSI pattern, 50% ?

Regards
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post #22 of 49 Old 04-16-2013, 11:24 AM
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You have to know what the "viewing angle" of your meter is... many meters have a VERY large angle of view and if you use a very small window size, the meter "sees" some of the black screen AND the pattern. That is NOT good. Any meter that is supposed to be very close to the TV probably has a very large viewing angle and using a small pattern will not work. Some meters "see" almost 90 degrees (45 degrees to the left, to the right, to the top and to the bottom).

You people (you and the people you are reading "information" from) are trying to make Cell Light into something that it is not. It is NOT a control that you should use.

Pick the mode on the Samsung that you want to calibrate (usually Movie mode). Set Cell Light to maximum. Set contrast to achieve about 33 fL (113 cd/m2). Then measure the different Gamma settings in the Samsung TV and use the Gamma setting that produces the AVERAGE gamma (all 10 points averaged together into 1 number) that is closest to your Gamma target (should be 2.25 unless you have a good reason to use some different Gamma target). Then use the 10-point controls to make every step in the grayscale equal to your 2.25 gamma target.

Trying to "beat" (or avoid) brightness limiting in plasma TVs is not good because the TV responds differently when the brightness limiting is active or inactive. When you use 10% window sizes, you get some of the effect of brightness limiting included in your calibration. This is a good thing, not a bad thing. Some people seemed to be obsessed with eliminating all of the plasma TV's brightness limiting during calibration... I believe that is THE WRONG way to calibrate plasma TVs. Yes, it would be good for plasma TVs to NOT have brightness limiting. But plasma technology (today) requires brightness limiting for the TVs to operate reliably for many years. Since the TV WILL have brightness limiting while you are using it, the brightness limiting should be part of your calibration process. Window sizes of 10% are the best compromise because they are small enough that brightness limiting does not dominate the calibration, but they are large enough that you do have SOME (small amount) of brightness limiting.

You have mentioned 120 cd/m2 several times... you do understand that you will only measure that value for 100% white with that number with 1 size of 100% white pattern? If you change the size of the pattern, you change the measurement... a smaller pattern will produce a higher measurement. A larger pattern will measure a lower number. So saying you measure 120 cd/m2 is only good for one size of pattern. If you measure 120 cd./m2 with a 4% window, you will measure maybe 60 cd/m2 with a full-screen pattern and maybe 90 cd/m2 with a 10% window size. So when you are talking about a plasma TV, your 100% white measurement does not mean very much when you do not include the size of the window pattern that you used. I believe that if you calibrate with a 4% window, you will NOT include enough of the APL range of the TV during your calibration and your ending calibration will be LESS good, rather than "better" as some people are trying to say.

Your point about use 1 size of pattern for calibrating and you are only linear for that 1 APL (average pcture level -- this is very different than ABL... average picture level is an average of the luminance of every pixel. So if 90% of the pixels are black (0) and 10% of the pixels are 100% white (I will use 100 cd/m2 to keep the calculation easy), your APL will be 10 cd/m2 for the 10% screen-size patterns when you measure 100 cd/m2 for 100% white. When you view many hours of TV content and measure the APL over many hours, you will get a number close to the same APL you get with windows that are in the 10%-16% size range. That is why we use window sizes in that size range to calibrate plasma TVs... the APL you use during calibration should be the same APL you experience when you view real video or movie content. You do NOT want to eliminate ALL of the influence of APL (by using very very small window sizes, like 4%, because you will NEVER view content on a plasma TV with APL that low (except maybe if there is a movie that is always dark). APL is linked to ABL but the relationship is not always what you might expect. HIGH APL usually causes the most ABL, and very small APLs mean there will not be very much ABL. But you must remember, you do not view TV or Movies with very very low APL very often. So your calibration SHOULD include some of the effect that APL has on ABL.

Your concern about making a large correction to fix gamma for some grayscale step being bad... that is not a problem for Samsung TVs. Samsung is the only TV manufacturer I know of who uses an 18-bit data processing path inside the TV. That means there is PLENTY of "space" for making large adjustments to controls without damaging the images. Other TV manufacturers may have data processing paths as small as 10-bits. I have seen Toshiba TVs where adjustments of more than 3 (range of control +/- 10) will cause severe damage to the picture because there is just not enough "space" in the digital range for the controls to do anything before running out of bits. (some earlier Toshiba TVs had control ranges of +/-30 but you could not use changes larger than +/-10 without damaging the picture badly). You will not have that problem with Samsung TVs.
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post #23 of 49 Old 04-16-2013, 11:43 AM
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You have mentioned 120 cd/m2 several times... you do understand that you will only measure that value for 100% white with that number with 1 size of 100% white pattern?

I assume when calibrators speak about peak white with plasma it´s measured from 10% size window, that´s what also I´m talking about smile.gif

Thanks again, good points about doing calibration with some ABL included.
I suppose 4% APL means size of windows and with background windows actual APL is something like 20% confused.gif
I read something about average APL 20% for movies and 40% for e.g. sport, is that correct?
You can find very variable long period measurings from web.

I have i1 Display Pro and for 2D meter is with contact to front glass (using also tripod for better focus centre of test pattern). Then wait something like 30 minutes for temperature balance before start measurings.
I don´t know about how wide is FOV for that meter. edit: found from web that it´s 7º

btw, is there somekind of "standard" for measuring 3D luminance? It depends what kind of 3D-glasses you are measuring through, how much those filter light.

edit:
Samsung released new firmware v.002007 but 720p bug is still there, you can´t disable overscan with internat tuner when receiving 720p signal, neither you can´t turn cinema mode Auto1/2 on with that signal.
Why the hell they can´t release FW where you can always disable overscan no matter what kind of resolution you´re receiving SD/HD. With SD there would be more use for that.
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post #24 of 49 Old 04-16-2013, 12:11 PM
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I don´t know about how wide is FOV for that meter.

check this: http://store.spectracal.com/article-why-viewing-angle-is-important

Your meter is the same as the C6
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post #25 of 49 Old 04-16-2013, 09:50 PM
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You have mentioned 120 cd/m2 several times... you do understand that you will only measure that value for 100% white with that number with 1 size of 100% white pattern? If you change the size of the pattern, you change the measurement... a smaller pattern will produce a higher measurement. A larger pattern will measure a lower number. So saying you measure 120 cd/m2 is only good for one size of pattern. If you measure 120 cd./m2 with a 4% window, you will measure maybe 60 cd/m2 with a full-screen pattern and maybe 90 cd/m2 with a 10% window size. So when you are talking about a plasma TV, your 100% white measurement does not mean very much when you do not include the size of the window pattern that you used. I believe that if you calibrate with a 4% window, you will NOT include enough of the APL range of the TV during your calibration and your ending calibration will be LESS good, rather than "better" as some people are trying to say.

Your point about use 1 size of pattern for calibrating and you are only linear for that 1 APL (average pcture level -- this is very different than ABL... average picture level is an average of the luminance of every pixel. So if 90% of the pixels are black (0) and 10% of the pixels are 100% white (I will use 100 cd/m2 to keep the calculation easy), your APL will be 10 cd/m2 for the 10% screen-size patterns when you measure 100 cd/m2 for 100% white. When you view many hours of TV content and measure the APL over many hours, you will get a number close to the same APL you get with windows that are in the 10%-16% size range. That is why we use window sizes in that size range to calibrate plasma TVs... the APL you use during calibration should be the same APL you experience when you view real video or movie content. You do NOT want to eliminate ALL of the influence of APL (by using very very small window sizes, like 4%, because you will NEVER view content on a plasma TV with APL that low (except maybe if there is a movie that is always dark). APL is linked to ABL but the relationship is not always what you might expect. HIGH APL usually causes the most ABL, and very small APLs mean there will not be very much ABL. But you must remember, you do not view TV or Movies with very very low APL very often. So your calibration SHOULD include some of the effect that APL has on ABL.

Doug,

Excelent text. Thank you.
I usually use AVSHD disk patterns. What pattern size do you recommend to measure overall luminance on Plasma Displays? Windows, Full fields, APL or another size?
And for front projection, what's the best pattern size?

Regards.
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post #26 of 49 Old 04-18-2013, 12:34 PM
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There is no one right answer to the above question -- the answer depends too much on the meter (and it's angle of view), the room (how close reflective surfaces are), and how sensitive the meter is to external reflected light.

In general, I prefer to not have a lot of extra, unmeasured, light in the room. So I use 10% windows for all types of displays... plasma, LCD, and projectors. I just keep the borders around the patterns black.

For CRT displays, Joe Kane found that an 18% window size was the best compromise and that is the window size he uses on his DVE discs, though I prefer a 10% window size for plasma because they do so much more brightness limiting than CRT displays.

But you have to keep in mind that some meters have a wide field of view and you have to keep the pattern large enough to fill that field so the meter is not seeing the black background. The meter I use has a 1-degree field of view, so I place it close to the viewing position and set it up so that the "line of sight" of the meter closely matches my line of sight when I'm watching movies.

One thing about plasma calibration... every method you use gives you a different end result. When you view content, often "different" wins over "better" (this applies to many things including video and audio evaluations) even if different isn't really better. So every time someone tries something "different" and says "Wow! I did this and it is wonderful." You have to question that sort of feedback and not assume it's an accurate reflection of reality -- that person may be convinced, but you can't know the process of how they got there.

I think one of the things about using constant APL patterns for plasma getting "popular" is that people understand that in a projection display with an automatic iris, you want to put the iris in a fixed setting for calibration and it's OK to turn the auto iris back on after calibratiion. And that is correct for projection systems. But brightness limiting in plasma displays doesn't work like an automatic iris... the black level does not get blacker when brightness limiting is high (the main way auto iris and brightness limiting differ). With an auto-iris, if the iris is full open for 1 scene, and 50% closed for the next scene, everything in the second scene is 50% dimmer. The shape of the gamma curve doesn't change (much, yes, it changes a little, but it's not a big deal). In plasma TVs, black is constant and brightness limiting affects the luminance in a non-linear way. You can't stop that from happening (except by changing to a display that's not plasma), so you need, IMO, to include SOME of that non-linear behavior within your calibration... I find 10% windows with black borders achieve that goal... they keep you from including a huge amount of brightness limiting without eliminating all of it.
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Thanks again, Doug.
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post #28 of 49 Old 04-20-2013, 07:31 AM
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You have mentioned 120 cd/m2 several times... you do understand that you will only measure that value for 100% white with that number with 1 size of 100% white pattern? If you change the size of the pattern, you change the measurement... a smaller pattern will produce a higher measurement. A larger pattern will measure a lower number. So saying you measure 120 cd/m2 is only good for one size of pattern. If you measure 120 cd./m2 with a 4% window, you will measure maybe 60 cd/m2 with a full-screen pattern and maybe 90 cd/m2 with a 10% window size. So when you are talking about a plasma TV, your 100% white measurement does not mean very much when you do not include the size of the window pattern that you used. I believe that if you calibrate with a 4% window, you will NOT include enough of the APL range of the TV during your calibration and your ending calibration will be LESS good, rather than "better" as some people are trying to say.

10% area windows do not impact peak white very much on recent plasmas, you need to get up to 20% by area before the ABL has any significant presence. Most of the recent discussion of gamma variation on plasmas from differing pattern sizes is due to changes in the lower stimulus levels and not peak white. To maintain the display at a constant operating point for calibration of gamma it is best to use APL patterns which replicate typical loading of 5-15% total energy (luminance) and approximately 20% average stimulus. This will ensure that your desired gamma is actually what you get for the majority of material you watch. If you use 10% windows on a black background all the lower stimulus levels (10-30%) will be brighter than they are during normal viewing which might cause you to darken them during calibration if you have 10 pt. controls. This will lead to higher than desired gamma for these levels during normal viewing.

2011 Samsung peak white and 20% gray response with pattern area loading


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post #29 of 49 Old 04-20-2013, 01:10 PM
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1) Your graph shows a TINY difference between 10% and 20% window sizes (gamma vs window size). So small as to make the size choice non-critical.

2) Different models produce different results.

3) Plasmas flicker pixels to produce levels below 100% (the pixels can only be 100% on or 100% off so they have to be flickered in a random pattern to produce lower luminance levels) and having perfectly linear gamma at lower luminance levels is not necessarily what you want to keep shadow detail from getting lost in the flickery pixel mess you have at low luminance levels.

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post #30 of 49 Old 04-21-2013, 08:26 AM
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Plasmas flicker pixels to produce levels below 100% (the pixels can only be 100% on or 100% off so they have to be flickered in a random pattern to produce lower luminance levels) and having perfectly linear gamma at lower luminance levels is not necessarily what you want to keep shadow detail from getting lost in the flickery pixel mess you have at low luminance levels.

Someones have report that they can see that flickering with Panasonic plasmas and not with Samsung plasmas.
Maby differences between that technology also explains differences with zoyd´s MLL vs. APL patterns between Panasonic and Samsung.
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