I'm confused on a few issues of monitor calibration...

If a monitor is properly calibrated using just a probe or photometer, making manual adjustments to RGB coordinates within the monitor controls, do you have to use a LUT as well?

If so, why is that?

I ask because I recently had my Sony PVM 2541-A calibrated. The person calibrating it said that he would does use LUTs because the photometer he uses is so accurate that it's not needed (Photo Research 655, I think was the model).

He said that you only need LUTs when you are calibrating via a probe because the LUT is designed to offset the inaccuracies of the probe...

Is this true? Can anyone clarify what he meant?

You are talking about two different levels of calibration...

Displays that have no user LUT capability, and rely one user manual controls will never be as accurate as those with use re-calibration capability, with LUTs.

And yes, that most definitely includes Sony!
We have had a lot of discussions with Sony, and for some reason that we don't understand they just will not allow external calibration access to their internal LUTs - which I suspect means they do not have calibration technology that they are willing to share, as it would then show the poor level of their internal calibration.

This is an example of a Sony OLED RGB Separation - a good indication of the accuracy of the calibration - and it's not good:



As for you calibrator saying he doesn't use LUTs as the Spectro. he uses is so accurate it makes LUTs unnecessary - that's just bollox!
A good spectro can't make-up for not having the accuracy of a good 3D LUT!
What it can do is improve the accuracy of the 3D LUT, over the potential inaccuracy of a tristim. probe...

Sorry to say you have been spun a pack of lies there...

I appreciate your candid answer.

So if I cannot upload LightSpace LUTs, does Light Space have a solution for us Sony OLED owners? If so, what exactly? How should I go about calibrating my monitor?

Many thanks, Steve!

First, I would profile the display and verify if it is accurate or not.
You can use the Free LightSpace DPS for that.

See: http://www.lightillusion.com/lightspace_dps.html

If calibration is needed, the best is to use an external LUT box, and run the display in Native/Raw mode (wide gamut) and use the LUT to do the calibration. (You can also use an Output or Display LUT held within the DI system!).

You MAY be able to run the display in native/Raw wide gamut mode and upload a 'look' LUT into the display, but Sony refuse to say if this will work, and I have not yet tested it.

(Some Sony displays have 'Look LUT' capability...)

Steve

desmondqford
Your story sounds like about me
I DID calibrate a PVM-2541A about a month ago and I DO have the PR-670 probe. This was in Russia. Aren't you from Moscow?
But I have never said the LUT is not necessary. Quite the contrary I DID recommend to my client to make a full profile of the monitor and use 3D calibration LUT in their Resolve.
The most problem of the unit I tested is even not the rgb separation but red and mostly green colours are out of gamut in dark, or in other words the picture is oversaturated in shadows. (don't know how to upload a picture to this forum ) This is for internal Rec709 correction is on. So, the only way to have the display fully calibrated is to switch off internal correction and use the external 3D LUT.

Regards,
Vassily.

Hi Vassily,

What you are saying is 100% correct!


This is a major problem with Sony monitors!!!
I really wish they would allow LightSpace integration...


But, I wonder if using the 'Look' LUT capability in Native/Raw mode would work???

To show a picture it needs to be hosted somewhere on-line.
Then use the 'camera' button above where you type a new message to link to it.

Steve

Not sure but afraid the PVM series does not have the 'look' LUT capability. Maybe BVM series does.

Ah! Good point!!!

No, Vasily, I'm in NYC... thanks for the input though.

Either way, I'm not trying to start any controversies here. I'm just extremely frustrated with the multitude of different opinions among authorities in the calibration world and I know that I'm not alone. I have spoken with product designers at Sony, FSi, several different calibrators, video engineers, DITs and colorists, and everyone has a different answer, some of which are completely at odds with each other!

Again, not trying to start any polemics here, just expressing a very real frustration...

So I've decided to take matters into my own hands... I took a calibration workshop here in NYC which was great. I'm taking a three day calibration certification training course form the Imaging Science Foundation in Denver, Colorado next month. Yes, I'm flying out to Colorado for three days just to take a calibration course... Yikes!

Sure, I could remain willfully ignorant, hire a professional calibrator, claim due diligence, wash my hands of the matter and get back to doing what I love: color grading. Thats just not me though.

Thanks, Steve.

Also, I've emailed you the calibration report I got form the calibrator. I'd be interested to hear what you think.

Hi Desmond,

Have got the report.
It's what I would expect for such a simple display profile and tweak.

The main problem is the probe could not read below 20% stimulus, which means you have no idea what is happening to the display in the shadows/blacks...

There is also no attempt to profile the gamut other than at peak stimulus - again, that can easily mean you have over or under saturated colours in the lower ranges, which is as Vassilly describes above.

The report also states a before/after contrast value.
Without being able to accurately measure black that is impossible to state!!!
So there is something very wrong there.

Beware of "authorities". Many calibrators have little education or training beyond a weekend seminar, and have no idea whatsoever what they are talking about. All the probes Steve sells are quite accurate, and the cheapest one is $300 or so.

Probes are not the issue (the worst probe, the i1Display Pro, is pretty good- the results of its measurements and those from a Hubble from direct experience are almost identical - certainly not something a client would ever notice, maybe rarely even me), the issue is how you measure data and what you do with it.

Without a 3D LUT, you will leave many problems behind, as most monitors have issues that are too numerous and too complex to be possible to fix with the few sliders you find in most on-board controls.