Official JVC RS20 / HD750 Calibration and CMS thread (NEW FIRMWARE V1.1) - Page 4

Okay, I have done more tests and I am happy to report that if I calibrate with my cheap Display2, the tracking in linearity at 100% and 75% is excellent, including on green. I now have some doubts again about my i1 pro, as the display2 measures THX the way we know it is (pretty accurate from a gamut point of view) while the i1 pro repots some undersaturation in green.

I am doing a calibration with the i1 pro now (I put my old lamp back to take the new lamp out of the equation), and I will post detailed data from both calibrations then. Hopefully this will help someone with a 750/rs-20 and a reliable meter to tell me which one I should trust...

Thanks Mark, but from my point of view if an i1pro just out of the factory is not to be trusted, then I'm thinking of giving up calibration altogether!

Here is some data from my latest experiments.

1) As Tom remarked, green was too bright in my first attempt. It looks like this was the reason why there was a lack of linearity in my results. Pushing green too high seems to disturb the linearity.

2) I have calibrated with both the i1 pro and the display2 LT, and although they do not return similar results, they track the same between 75% and 100% as long as green's brightness is within reason. So my apologies for the first results: I repeat it for clarity: there is NO linearity problem with the new CMS. There are minor variations, but they are within what one could expect and are far beyond what I would personally expect from a consumer product.

3) I have taken my new lamp out and put back my old lamp, so the settings below may be better for some PJ.

4) There is a substantial difference between the measures taken by my i1pro and my d2. I attach a few files for those who are willing to look at the details, but would really appreciate if a 750/rs20 user with a meter they trust could try both settings below and tell me which one looks closer to rec709 on their PJ. I have my own opinion as to which one looks more "right", but I would rather not influence anyone.

I have calibrated with the i1pro in user1/custom1, and with the d2 in user2/custom2. I have set gamma to normal and color temp to the default 6500K in both to make sure I'm not introducing unknown variables to the equation.

Here are the settings (HSB):

user1/i1pro:
R=-4 -21 -2
Y=31 -44 40
G=-7 -42 34
C= -14 -49 40
B=30 0 -10
M=-7 0 -6

User2/d2:
R=-15 -16 -3
Y=7 -48 40
G=-36 -45 34
C= 13 -56 51
B=34 0 -7
M=-16 0 -4

As you can see, a pretty substantial difference!

The biggest being hue for cyan and green.

I have obviously not finetuned either of these calibrations as I need to find out first which meter is "right", if any.

Please Do not pay attention to the greyscale info if present in the attached files. I've only worked on the gamut.

 

2nd atttempt.zip 111.1708984375k . file

Last screenshots (i1Pro):

And just for fun, this is how the i1pro measures the d2 calibration:

Re Tom's comment, you are right, he never said this. I have compared the new calibration with the i1pro and the old one, and green brightness was too high in the old one. Hence my deduction.

I went back to the old bulb without changing the settings, and the lack of linearity was still there (so putting the old bulb back didn't solve the problem).
It's only when I realised brightness for green was too high and adjusted it that the linearity problem disappeared.

Regarding the greyscale, I agree with you that this is the procedure that should be followed, but I'm not sure I understand in which way this is relevant here. There is no linearity problem with the new CMS, whether I calibrate to rec709 with the i1pro or the d2, as proved by the last files I've posted.

The only problem I have is I don't know which meter to trust, as they measure very different. But maybe I should take this discussion out of this thread, as it has nothing to do with the new CMS (apart from the fact that it would help me to provide better settings if I knew which meter to trust).

This is illustrated by the fact that the d2 measure the THX gamut as very close to rec709, while the i1pro measures it with green undersaturated.

Are you saying that doing the grescale will put the i1pro and the d2 on line? I don't understand why.

And which meter should I use to do the greyscale, if I don't find a way to decide which one should be trusted?

If there is no other way, I will follow Mark's suggestion to try to find someone with a reference meter, or maybe try another i1pro. I was sent a second one by mistake, I may open it and see if it measures the same.

Thanks Tom, that's also what I think. The problem is that my eyes tell me the i1pro is correct (when do my greyscale with it, it's perfect, when I do it with the d2, it's slightly reddish). Unfortunately, the i1pro measures THX with a substantial green deficiency, while the d2 measures it bang on rec709. This is what throws me. I think we all agree that THX is rather close from a gamut POV, so I can't explain why the i1pro sees it so wrong.

Thanks LovingDVD, but the difference in meters is the only thing we are still discussing. I have used the d2 trained with the i1pro, and it's provided a more more precise and repeatable way to do work on the greyscale. It's just that calibrating after installing the new firmware threw that question about green variation and I'd like to get to the bottom of it.

I'm going to open a new thread if I don't find a way to solve this as this is distracting regarding the new CMS, which performs flawlessly as far as I can see.

I don't want my meter problems to take anything away from JVC's extraordinary achievement.

This new firmware rocks (and at least one of my meters suck$).

Craig, the new CMS tracks in a perfectly linear way. I am sorry my meter problems raised a question about this, but as far as I can see, there is NO linearity issue with the new CMS. Full stop.

Yes, but how do you want me to do the greyscale if I don't know which meter to use?

I could do two greyscales, one with each meter, they would both measure perfectly with each meter.

But they would both be different.

So which one should I use to work on the gamut?

This is why I reverted to the 6500K setting, just to take greyscale out of the equation.

As I said, my eyes tell me the i1pro is more "right" than the d2. If it was showing the THX gamut on rec709, we wouldn't even be discussing this. What I find puzzling is the fact that it's the opposite, the D2 shows THX on rec 709, and the i1pro shows it substantially undersaturated.

Thanks 008, this is good to hear.

To me, the i1pro does look more right than the d2, especially when looking at a greyscale done by each separately (steps of grey with the i1pro, slight red tint with the d2).

I'm going to assume the i1pro is more right, that THX is off (as I also felt THX was undersaturated), work on the greyscale like I used to with the D2 trained on the i1Pro, and I'll report with a final calibration.

Hopefully this will put the matter to rest!