PZ800 n00b Calibration Questions - AVS Forum
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post #1 of 12 Old 05-16-2012, 09:01 PM - Thread Starter
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Hi All.
I'm delving into the world of DIY calibration on my PZ800 Plasma in an effort to maximise it's picture until I can afford a newer model. (AUS model, no THX)
It's in a reasonably bright lounge-room, and I have bias lighting for when watching in the evenings.

Anyway, i've previously "calibrated" it by eye using the THX optimiser disk and filter glasses to get a reasonable picture.
I've now bought an i1 D2 and using HCFR and the Dummies guide have come up with the following baseline after running a quick scan over the set

it's reasonably bright with peak output around 55FtL

I use the "Normal" picture setting (Cinema measures exactly the same gamma curve, just shifted lower)
And the "Normal" Colour temp, it looks more natural than the warm temp in this state






My main questions are
1) HCFR has a few options for target gamma. The dummies guide shows "Display Gamma with black compensation" selected.
What is different between this option and the "Display Gamma" option.
Which should i be using?

2) from my RGB Luminance graph, we can see that the luminance is slightly too high for all colours in the <50 IRE region.
No doubt that would help explain the low gamma in that region too.
Without an external processor, can this luminance be lowered with the individual RGB or All RGB Drive controls in the service menu?
OR lowering the user-menu colour (croma) control?

And my Service menu also has a "Sub-Brt" control, but i assume that only affects the same region as the user-menu Brightness control?

I'm pretty happy with the picture as it stands but i can definitely see, even by eye, that it needs to be slightly warmer.
Hopefully, warming it up (lowering blue) may even bring that gamma up in the low end a little.

I can't find my measurement images from the readings i took in cinema-normal mode. but the luminance level was even higher in that <50IRE region.
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post #2 of 12 Old 05-17-2012, 04:08 AM
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Quote:
Originally Posted by Robbks View Post

Hi All.
I'm delving into the world of DIY calibration on my PZ800 Plasma in an effort to maximise it's picture until I can afford a newer model. (AUS model, no THX)
It's in a reasonably bright lounge-room, and I have bias lighting for when watching in the evenings.

Anyway, i've previously "calibrated" it by eye using the THX optimiser disk and filter glasses to get a reasonable picture.
I've now bought an i1 D2 and using HCFR and the Dummies guide have come up with the following baseline after running a quick scan over the set

it's reasonably bright with peak output around 55FtL

I use the "Normal" picture setting (Cinema measures exactly the same gamma curve, just shifted lower)
And the "Normal" Colour temp, it looks more natural than the warm temp in this state

You'll get better color reproduction if you use the warm temp and then tweak that to D65.

Quote:


My main questions are
1) HCFR has a few options for target gamma. The dummies guide shows "Display Gamma with black compensation" selected.
What is different between this option and the "Display Gamma" option.
Which should i be using?

black compensation subtracts the level 0 reading off all the luminance's and then fits the curve. It doesn't really matter which you choose since you don't have the controls to modify the gamma curve.

Quote:


2) from my RGB Luminance graph, we can see that the luminance is slightly too high for all colours in the <50 IRE region.
No doubt that would help explain the low gamma in that region too.
Without an external processor, can this luminance be lowered with the individual RGB or All RGB Drive controls in the service menu?
OR lowering the user-menu colour (croma) control?

No, the RGB controls can be used to correct the color temperature but not for gamma adjustment. Your gamma curve is actually not too bad when compared to the bt.1886 recommendation for a display with mll ~0.1 cd/m^2, what is your mll?
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post #3 of 12 Old 05-17-2012, 06:00 PM - Thread Starter
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Quote:
Originally Posted by zoyd View Post

You'll get better color reproduction if you use the warm temp and then tweak that to D65.

Warm Picture mode was too warm by 900K,
The same amount that Normal is too Cool by 900K.
It would be the same adjustment i'd think?
Just lowering red instead of lowering blue
leaving green as reference and tweak if needed, the luminance graph shows a little green bump at 90

Quote:
Originally Posted by zoyd View Post

black compensation subtracts the level 0 reading off all the luminance's and then fits the curve. It doesn't really matter which you choose since you don't have the controls to modify the gamma curve.

My DVD player (Denon DVD2930) does have 10pt Gamma controls and it's HDMI input will be calibrated independently of the other sources.
Should there be a need to tweak the greyscale for colour after making gamma adjustments?
And does this affect the black compensation option?

My PVR input will be calibrated with the AVSHD MP4 files and i'll transpose those values to the Satellite box and FTA inputs

Quote:
Originally Posted by zoyd View Post

No, the RGB controls can be used to correct the color temperature but not for gamma adjustment. Your gamma curve is actually not too bad when compared to the bt.1886 recommendation for a display with mll ~0.1 cd/m^2, what is your mll?

Mll was measured at 0.07cd/m2 (0.019FtL)

Am I wrong in thinking that the luminance (Chroma) of each colour channel would have an effect on the Gamma?

i.e if the panel is trying to produce say, 10% grey, if luminance of all colours were too high at that point, (although in the right proportions to achieve D65) the actual output would be whiter,
thus lowering the Gamma at that point?

and i'd assume that the only luminance control we have is the basic "Colour" control, which would affect the entire greyscale
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post #4 of 12 Old 05-17-2012, 06:55 PM
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Quote:
Originally Posted by Robbks View Post

Warm Picture mode was too warm by 900K,
The same amount that Normal is too Cool by 900K.
It would be the same adjustment i'd think?
Just lowering red instead of lowering blue
leaving green as reference and tweak if needed, the luminance graph shows a little green bump at 90

yes, sometimes warm is closer but you can start from either.

Quote:


My DVD player (Denon DVD2930) does have 10pt Gamma controls and it's HDMI input will be calibrated independently of the other sources.
Should there be a need to tweak the greyscale for colour after making gamma adjustments?
And does this affect the black compensation option?

Depends on how the denon 10pt interacts with greyscale, you'll definitely need to check it and you may end up with a grey scale that only works with the denon (or some compromise).

Quote:


My PVR input will be calibrated with the AVSHD MP4 files and i'll transpose those values to the Satellite box and FTA inputs

Mll was measured at 0.07cd/m2 (0.019FtL)

Am I wrong in thinking that the luminance (Chroma) of each colour channel would have an effect on the Gamma?

i.e if the panel is trying to produce say, 10% grey, if luminance of all colours were too high at that point, (although in the right proportions to achieve D65) the actual output would be whiter,
thus lowering the Gamma at that point?

and i'd assume that the only luminance control we have is the basic "Colour" control, which would affect the entire greyscale

You can follow the bt.1886 guidelines using the calculator found here for gamma which take into account your peak white and mll values or just shoot for a traditional flat 2.2 - use the display gamma fitting function without black compensation.

The color control is not the kind of luminance control you are thinking of, it's the decoder chroma gain control that affects all colors and needs to be set by matching the luminance of one of the colors (usually blue or red) to the correct proportion relative to white luminance. This can be done in HCFR by minimizing delta luma in primaries/secondaries measurements box. You can't use color as a gamma control. The display's native gamma will be your only option for the inputs other than the denon unless you invest in an external video processor.
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post #5 of 12 Old 05-17-2012, 07:06 PM - Thread Starter
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Quote:
Originally Posted by zoyd View Post

Depends on how the denon 10pt interacts with greyscale, you'll definitely need to check it and you may end up with a grey scale that only works with the denon (or some compromise).

Yeah i figure i'll calibrate the Cinema preset which has the same gamma curve as Normal, except the Cinema is shifter 0.1 lower across the whole greyscale.
I can then use it's built-in processor to target 2.2.
that will leave the Normal (closer to 2.2) preset for the other inputs

Quote:
Originally Posted by zoyd View Post

The color control is not the kind of luminance control you are thinking of, it's the decoder chroma gain control that affects all colors and needs to be set by matching the luminance of one of the colors (usually blue or red) to the correct proportion relative to white luminance. This can be done in HCFR by minimizing delta luma in primaries/secondaries measurements box. You can't use color as a gamma control. The display's native gamma will be your only option for the inputs other than the denon unless you invest in an external video processor.

thanks for clearing that up!!!

now, just have to find some time to get it done.
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post #6 of 12 Old 05-22-2012, 11:20 PM - Thread Starter
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zoyd, another question for you
I've been reading over and over the power-law gamma thread
but every time i read it i get myself both more familiar and more confused.

But basically, we are trying to achieve the same luminance (Y) reading on our own displays for a particular stimulus level that was seen on the monitors in the mastering studio.

Now the question is.
we are obviously trying to target a specific output luminance (Y) for each level of input stimulus from the source material?
do we know these specs of the reference monitors?

rather than trying to work out some function of input vs output for our devices that don't behave naturally like the reference monitors do.
We just need to know what the target luminance actually is?

I just know i hate gamma corrections already

EDIT:
after re-re-re-re-re-re-reading that thread,
I assume that's what your calculator that you linked before provides.
in primary and Alternate values.

And a question on the calculator
MLL input of .07
Peak white of ~200

IS gamma 2.4 (in the greyed out calculator box) the correct fixed value for the entire calculation? or is there circumstances that it should be changed
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post #7 of 12 Old 05-23-2012, 03:43 AM
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Quote:
Originally Posted by Robbks View Post

zoyd, another question for you
I've been reading over and over the power-law gamma thread
but every time i read it i get myself both more familiar and more confused.

But basically, we are trying to achieve the same luminance (Y) reading on our own displays for a particular stimulus level that was seen on the monitors in the mastering studio.

Now the question is.
we are obviously trying to target a specific output luminance (Y) for each level of input stimulus from the source material?
do we know these specs of the reference monitors?


yes, theoretically you want to have each stimulus level produce exactly the same luminance on your display as was produced on the mastering display. At least that should be your starting point before considering how viewing environment might be compensated for.

Quote:


rather than trying to work out some function of input vs output for our devices that don't behave naturally like the reference monitors do.
We just need to know what the target luminance actually is?

I just know i hate gamma corrections already

EDIT:
after re-re-re-re-re-re-reading that thread,
I assume that's what your calculator that you linked before provides.
in primary and Alternate values.

And a question on the calculator
MLL input of .07
Peak white of ~200

IS gamma 2.4 (in the greyed out calculator box) the correct fixed value for the entire calculation? or is there circumstances that it should be changed

The key statement from the recommendation is this:

Quote:


In measuring the EOTF of a large number of CRTs it was determined that the EOTF of the CRT was in fact highly variable when the brightness/contrast was adjusted, it is therefore not possible to 100% emulate CRT capability (or limitations).

So they developed an approximation to the EOTF which includes the brightness/contrast accommodation. In the limit of 0 mll this function goes to a constant power law 2.4
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post #8 of 12 Old 05-23-2012, 04:28 PM - Thread Starter
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just to add information for future reference (i haven't found this elsewhere)

Recommendation ITU-R BT.1886 (03/2011)
http://www.itu.int/dms_pubrec/itu-r/...3-I!!PDF-E.pdf

Cheers for your help.

I haven't been using my maths skills for the last few years.. now it's all coming flooding back... unsure if that's a good thing or not
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post #9 of 12 Old 05-27-2012, 11:19 PM - Thread Starter
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Just another question here.

I went about getting my greyscale and colour temp sorted out today and have it pretty spot on, DE's are under 3 for the whole greyscale.
But, the Luminance graph has moved further towards the top LH corner (away from the target) but all colours still track on top of each other.

How/ where would I begin rectify this?
The main colour control?
or is this just a function of my brightness and contrast (quite high) settings

Cheers
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post #10 of 12 Old 05-28-2012, 06:17 AM
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Post your a chc file with greyscale and primaries/secondaries. Does the display have CMS controls?
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post #11 of 12 Old 05-28-2012, 04:57 PM - Thread Starter
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No CMS controls other than 2 point cuts/ gains and colour/ tint controls

here's the two HCFR files.
one with the colour slider at 40 and the other at 50.
only other change between runs was to bump the red in both ends by 1point in the SM

 

HCFR.zip 1.9072265625k . file
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File Type: zip HCFR.zip (1.9 KB, 0 views)
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post #12 of 12 Old 05-29-2012, 05:37 AM
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Given your oversaturated primaries the 40 color setting where you minimize dE of red by undershooting luminance is probably the best you can do. Grayscale 20,30 points look like they could use a touch more blue but check by eye on 5 and 10% patterns.
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