# Calibration experience and questions



## glaufman (Nov 25, 2007)

Hi all-
So this is a followup to my thread on my dad's Sharp ACquos 42HDS69 which I went over and adjusted for him... (I call it a basic calibration, but I know that can be a controversial term for what I did)...
What I did was use a cal disk in his BD player (the Panny 210 which I bought him for his birthday to go with this first HD set he just got used from a friend)...

Anyway, my experience, and some question that have resulted...

To my surprise, when I started I found that both blacks and whites were being crushed, and nothing I did to the brightness/contrast controls could change any of that... in any video mode..

What did work was changing video modes on the BD player. It's been a while, so I don't remember precisely, but I think it was changing the player from standard to movie mode... not too surprising given the name of the modes, but I never expected a Panny player to do that much damage to the signal integrity... at any rate, I left it clipping black around 18 and white around 240+something...

At any rate, to cut out all the boring stuff in the middle, when it was all said and done I made a vast improvement to his picture quality, but what I was still disappointed in was the gamma ... if memory serves it was down below 2.2 at maybe 2.1 or even 2.0... His viewing environment is fairly bright, so that gamma isn't terrible, but I would've like to improve it a bit. I played a little with the brightness and contrast first on the tv, then on the bd, but doing so just messed things up a bit.

The BDP has a gamma control... would any of you pros out there use this to tweak the gamma, or would that just do more harm than good? 

Similarly, I left his sharpness control all the way down... as I always do when I see no ill effects, but a question raised in my mind... would anyone raise that up until overshoot/undershoot was visible?


----------



## Joel Barsotti (Nov 26, 2011)

What controls where you changing in the BD player?
It sounds like the BD player has the wrong black level or pixel format selected, if you're tweaking brightness/contrast on top of that you're going to get sub-optimal results.

You should set the Display to have 16 = 0%, so you might be able to see 17,18,19 or not, 20 you should probably be able to see. But what you really want to do is back down brightness till 16 completely disappears against 0.

Contrast should run all the way to 255, with no discoloration (acutally just a R,G or B channel clipping lower than the other channels).

I wouldn't use gamma controls in a BD player. A gamma of 2.0 would be fine for a bright room, even then gamma is the least of your worries, so if it's not spot on and the display doesn't have gamma controls, don't worry about it.


----------



## glaufman (Nov 25, 2007)

Thanks for the feedback


Joel Barsotti said:


> What controls where you changing in the BD player?


IIRC, I took it out of "standard" mode and put it into either "movie" or "cinema". That stayed put. I may have played with the brightness/contrast/gamma controls, but ultimately put them back where they started.


> It sounds like the BD player has the wrong black level or pixel format selected, if you're tweaking brightness/contrast on top of that you're going to get sub-optimal results.


Not sure what controls there are to change that.


> You should set the Display to have 16 = 0%, so you might be able to see 17,18,19 or not, 20 you should probably be able to see. But what you really want to do is back down brightness till 16 completely disappears against 0.


Of course. But nothing I did in the TV user menu could get me there. That's why I'm asking about the BDP controls.


> Contrast should run all the way to 255, with no discoloration (acutally just a R,G or B channel clipping lower than the other channels).


I agree, but again, nothing in the TVs user menu got me there. so I got it as high as I could, and stopped raising it when I stopped see improvement. I also don't view this as being quite as critical as the black clip.


> I wouldn't use gamma controls in a BD player. A gamma of 2.0 would be fine for a bright room, even then gamma is the least of your worries, so if it's not spot on and the display doesn't have gamma controls, don't worry about it.


It may have been even lower than that. I have data I took in HCFR, but it's on my other computer at home, and I'm on the road at the moment. Nontheless, I believe there are gamma and wb controls in the service menus, but as I couldn't make heads or tails of the descriptions in the service manual, and some other considerations including the poort environment, I opted to stop short of going there.

So you believe like I feared, that gamma controls in the BDP, with the presumably necessary calculations, would probably do more harm than good?


----------



## Joel Barsotti (Nov 26, 2011)

The guys over at home theater secrets reviewed that model and found the correct settings to make the player as accurate as any pattern generator.

http://www.hometheaterhifi.com/blu-...-ray-player-for-the-home-theater.html?start=3

For the TV there is a HDMI mode you may need to force it to video mode.

Also for sharpness I'd go with the same methodology as brightness, turn it up till it's too high, then back it down till it looks right and leave it at the highest setting that doesn't appear to add any sharpness. Also make sure you're in Dot by Dot mode.


----------



## tbaudoin (Mar 19, 2012)

I've got a dell XPS15 and had to do a rebuild. Now have issues with Powerddvd 9.6. Only want to use the laptop for calibration and a bit afraid of installing it again and don't have the nvidia 435 control panel activated. Need some help info to verify the setup and a pattern source and advice as to whether to activate the control panel, what media player if any (other than cant play blurays now) is the simplest to setup without having to flip settings for a calibration stream versus playback. I mainly wonder if the video controls of the nvidia influence the output the pcclient. Sorry if this is convoluted, but so am I at the moment. Thanks. T


----------



## Joel Barsotti (Nov 26, 2011)

tbaudoin said:


> I've got a dell XPS15 and had to do a rebuild. Now have issues with Powerddvd 9.6. Only want to use the laptop for calibration and a bit afraid of installing it again and don't have the nvidia 435 control panel activated. Need some help info to verify the setup and a pattern source and advice as to whether to activate the control panel, what media player if any (other than cant play blurays now) is the simplest to setup without having to flip settings for a calibration stream versus playback. I mainly wonder if the video controls of the nvidia influence the output the pcclient. Sorry if this is convoluted, but so am I at the moment. Thanks. T


You can't trust a PC at all unless you run it against a reference generator.

Also the video card can change it's output depending on the EDID of the display it's connected to and not show that it made any changes.

Using a PC as a pattern generator is a very dangerous path to go down.


----------



## tbaudoin (Mar 19, 2012)

Joel Barsotti said:


> You can't trust a PC at all unless you run it against a reference generator.
> 
> Also the video card can change it's output depending on the EDID of the display it's connected to and not show that it made any changes.
> 
> Using a PC as a pattern generator is a very dangerous path to go down.


My middle name is "danger". Appreciate your knowledge and accessibility. It must be a blast to know exactly how and why all the parts and pieces are intended to interact and the limitations. I was just under a delusion that it would be a rather compact and slick setup. Guess I need some stimulus to my passion profession funding. Thanks. T


----------



## tbaudoin (Mar 19, 2012)

Joel Barsotti said:


> You can't trust a PC at all unless you run it against a reference generator.
> 
> Also the video card can change it's output depending on the EDID of the display it's connected to and not show that it made any changes.
> 
> Using a PC as a pattern generator is a very dangerous path to go down.


Will contact you directly, can send pm yet via this forum. T


----------



## tbaudoin (Mar 19, 2012)

If the second display can be set via the NVIDIA control panel to a display compatible resolution, what would it be? I noticed 16 & 32 bit versions of my displays. Which is the right/better choice? 

Am I missing the point? Are you aware of any testing of laptop/video card combos for this purpose?

Thanks, T


----------



## tbaudoin (Mar 19, 2012)

I just checked, and if I look at all resolutions available, I have 8, 16, and 32 bit versions of output resolutions down to 800x600.


----------



## Joel Barsotti (Nov 26, 2011)

The issue is how do you know what the laptop is putting on the wire?

I have an ATI video card in my laptop, when you set it to RGB full, it says that it's doing 0-255, but it's not.

Also if you use YCC, there is an error in the RGB->YCC conversion that causes a slight green shift. Also it's compressing the range on the desktopt to 16-235, so desktop black of 0 is actually going on the wire with a Y value of 16. 

Here's the real kicker though, when you look at the output with a scope you can see very clearly the RGB lines don't track correctly so the value of desktop black 0 isn't 16,128,128 in YCC like it should be, but more like 16,125,125.

But you'll never know any of this unless you either have a reference device to compare to the measurements you are getting from the PC or you've got a scope to visualize the signal.


----------



## tbaudoin (Mar 19, 2012)

Well, don't have a reference pg at the moment, else this discussion would be sinlos (pointless). Not sure what and how to set up a "scope". I assume I might know someone with the right toy. Maybe they will have a method to do this, else I can root around on bd test sites to see what they are doing. What have you done to discover this issue? T


----------



## Joel Barsotti (Nov 26, 2011)

Home theater secrets have done some reviews on blu-ray players.

Bit perfect blu-ray players + a good calibration disc like the AVS rec.709 disc can stand in for a reference pattern generator.

You just need to get a known quantity to start comparing against.


----------



## tbaudoin (Mar 19, 2012)

So, I grab a player that has been deemed close to bit perfect. What pattern or set of patterns would be used to look at one signal on the BDP (as a reference) versus a signal from the LTPC? What readings will give me this information, grayscale or primaries and scondaries, or ?? BTW, is there an assumption that any purchased disc with similar fields would produce exacting enough results, or it this flawed logic as well?

Basically how do I know one set of patterns on disc is 75% Red versus another of a different manufacturer.

Sorry for the basics, but where else can I get so saturated with good info!~
T.


----------



## Joel Barsotti (Nov 26, 2011)

Not all discs are equal, but the AVS disc is right, I believe the DVE HD disc also has the patterns.

What to compare is the grayscale readings and gamut readings.

If the Readings from 0-100% are within reading-to-reading error, then you are good. If the readings are consistently different by a repeatable margin, then you've got a problem.


----------



## bigjbk (Jan 28, 2012)

Thanks home theater shack for the advice and the recommendations for the tools. I will be purchasing the DVD tool for further calibration and testing. I love this site!!!


----------



## tbaudoin (Mar 19, 2012)

Trying to experiment/learn how calibration "works" and how the NVIDIA CCC generates a different output (as it would relate to calibration) verifying against what I have available: XPS Laptop w/435M card, Sony 46" XBR929, Sony S780 BDP, DVE, Spears, AVS MP4 files. 

Here's where I am at the moment. I have compared the setting I have on the 929 against the PC-AVSMP4 and also the other BDs through the 780BDP. They all essentially indicate similar results. No change needed.

However, when I sent the PC Client PLUGE it is not in agreement with either the MP4 or BD (DVE or Spears). So, I have been told, to set the BTB/WTW in NVIDIA to match my "chosen" reference. This is easy enough, but here is what I discovered.

If I use Dynamic on the CCC (16-235) I can still adjust BTB/WTW; if I use 0-255 I get BTB/WTW, but neither agree with MP4/BD. Also, to match either setting above, requires completely differenct Brightness/Contrast settings. It is very interesting, but I don't quite know what to make of it. And not sure what it is doing. But, unless adjusted, still no PLUGE in PC Client matches the "chosen references". 

What about the gamma settings and color settings? If I leave gamma at the default 1.0, it doesn't match any "chosen reference" pattern used. So, next I plan to try how the PC set BTB on different rough gamma setting (meaning not measured, but more seeing if anything gets close enough to the chosen references before getting out a meter, the change is rather obvious at 1 v 2). How should this likely be set -0 or 2.2, since it is output? (not wanting to get too far into theory and Ponyton for this purpose). Does, can this be related to how AVS v PC Client is mastered or PCdom? If I match the mastered Gamma (0) would be my assumption that it is to allow for CalMan to set the gamma multiplier or not to jeopardize how CalMan is designed to be accurate with a multiplier that is chosen or is that just as subjective as the determining a reference? If so, I would assume I would need to run some gamma measurements to try to get as close to 2.2 (if this is my target Calman), or is there an easier way. I basically am wondering if the gamma out of the PC, impacts the calibration the same as other sources? Therefore, treat the PC as no more than a source as I work from closed loop to an array of components connected to the display.

This is fun stuff, and the discoveries/lesson keep on coming.

Regards,
T.


----------

