Official JVC RS20 / HD750 Calibration and CMS thread (NEW FIRMWARE V1.1) - Page 18 - AVS Forum
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post #511 of 1634 Old 05-09-2009, 06:44 PM
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Quote:
Originally Posted by Lawguy View Post

Whoever is responsible for the myth that calibrated colors are dull or lifeless should take a look at what I am seeing on my RS20.

I am really SO pleased with everthing about this projector right now. I am not saying that I am expert calibrator (far from it) but I know this is an accurate calibration. If you can't do this yourself, pay someone that you know is capable to do it for you. This calibration really took things to another level for me.

I hope that is how it works for me. My i1pro is due on Monday. I am just getting started down this road.

Never become so involved with something that it blinds you.
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post #512 of 1634 Old 05-09-2009, 07:39 PM
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I calibrated another RS20 today and I have some new data. From the two units I have seen, it seems that the gamuts are very consistent, but the 6500K Color Temp that THX uses varies quite a bit.

First, the THX mode

THX x y Y CIE94 L S H
W 0.315 0.337 1.000 4.6
R 0.642 0.330 0.215 0.4 0.4% 0.6% 0.0%
G 0.313 0.589 0.715 2.0 0.0% -4.6% -4.4%
B 0.147 0.064 0.071 2.0 -0.9% -2.6% -2.3%
Y 0.423 0.504 0.899 1.4 -1.2% 0.2% -2.4%
C 0.234 0.340 0.781 2.8 -0.3% -6.9% -10.5%
M 0.331 0.163 0.280 1.6 -0.7% -4.0% 5.6%

Next, the User 1 mode pre-calibration.

User1 x y Y CIE94 L S H
W 0.314 0.338 1.000 4.6
R 0.672 0.326 0.220 5.9 1.5% 12.6% -1.0%
G 0.286 0.699 0.707 9.5 -0.4% 22.6% 2.3%
B 0.140 0.052 0.064 2.2 -5.8% 5.9% -1.9%
Y 0.442 0.548 0.928 9.9 0.0% 17.2% 1.4%
C 0.206 0.343 0.773 6.0 -0.7% 24.0% -10.0%
M 0.330 0.149 0.286 1.8 0.1% 7.1% 4.5%

Next, the THX mode at 50% saturation.

50% R G B
x 0.479 0.317 0.244
y 0.334 0.458 0.213
Y 0.212 0.715 0.072
CIE94 1.0 2.4 2.2
L 0.0% 0.0% 0.0%
S -0.4% -6.3% -16.8%
H 2.1% -7.5% 1.4%

As you can see, red is essentially perfect. Green is off a little, but that is as much due to a correctable hue problem. Blue has the biggest problem, but the dE is relatively small. It seems that this PJ is fairly linear throughout the color space.

Finally, offsets between my Chroma 5 colorimeter and Orb spectroradiometer.

x y
W 0.004 0.006
R 0.000 0.001
G -0.002 0.004
B 0.004 -0.001
Y -0.002 0.003
C 0.003 0.008
M 0.006 0.001

As you can see, the offsets are very small, with white and cyan having the biggest problem. This is consistent with what I saw on the other RS20 as well. This PJ is a fairly easy unit to calibrate with a good colorimeter, which is not surprising as it uses a standard UHP bulb.

As I reported earlier, a post-calibration User 1 measures almost perfectly in all respects.

Tom Huffman
ChromaPure Software/AccuPel Video Signal Generators
ISF/THX Calibrations
Springfield, MO

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post #513 of 1634 Old 05-09-2009, 09:41 PM
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First, sorry if I missed this and it has already been discussed.

I sold my RS20, so can't do this myself, but I did calibrate it before I sold it and I had to lower the blue gain quite a bit. I don't remember how much extra blue I would have had with all the gains at 0 though. Since some other numbers I've seen indicate that other people have had to lower the gain for blue a fair amount, I'm wondering if anybody is considering doing this with a color filter instead. A filter that filters some green and more blue would seem ideal, but I'm not sure how much would be called for. I have an FL-Day filter, but no RS20 to try it on.

Anyway, one reason I think this could be extra helpful is what dcouzin posted about here:

http://www.avsforum.com/avs-vb/showthread.php?t=1145337

Basically, our vision in the darkest stuff tends to be skewed much more toward seeing blue and not red. So, while getting rid of some blue in the absolute black while lowering the blue in reference white optically could help the on/off contrast ratio measurement some, it could actually help the perception even more than the measurement using the photopic curve (basically what applies to brighter scenes) would indicate.

BTW: I used Calman with my EyeOne and one of the DPG-1000 Digital Pattern Generators from them. It was so nice to be able to kick off a set of measurements and just let the tools auto change the test patterns and do the measurements instead of having to manually change the test pattern and kick off the reading every time. I was able to do some other things around the house in the breaks while it was measuring a sequence for me.

--Darin

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post #514 of 1634 Old 05-09-2009, 09:57 PM
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While I was measuring the primaries on my RS20 I was having some trouble measuring the blue primary. I ended up looking at the spectral curve in Calman and one thing it showed me is that the amount of red the tool was indicating for the blue primary (I think 100% level, but not positive) where I was aiming for REC.709 blue was about the same amount of red that it would indicate in a 30%stim gray image. The amount of signal the meter was reading in wavelengths in the green range was lower than it indicated for green in a 30% stim gray image. I should have saved images of those 2 spectral graphs so I could post them, but I didn't.

But for anybody using a spectroradiometer I think it could be interesting to look at what the spectral graph indicates is being read for levels of green and red while trying to adjust the blue primary, compared to what it reads at some different gray levels.

In my case I had put the projector about halfway to the screen with a smaller than normal image to try to get brighter images to hopefully help the accuracy of the measurements. I think my white level for this one was a little under 30 ft-lamberts.

--Darin

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post #515 of 1634 Old 05-10-2009, 12:08 AM - Thread Starter
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Quote:
Originally Posted by millerwill View Post

Wow, Manni, a big change in Blue!

My observations, though, are still pretty much as earlier; probably just a diff in our pj's and screens (I have an HP).

I find Manni's CMS to give the reddest skins tones, LG's the palest, and Ldvd in between. But they are all VERY close! If you just look at one of them for a while, it seems totally natural. Only by switching between them do you notice small diff's.

Thanks Millerwill for the feedback. The change in blue looks big because I used the opposite way to get it there (sat instead of hue), but it's primirily the brightness that was off. I think this approach creates less side effects.

At this stage, the calibrations between LDVD, LG and me show mostly differences in setup (PJ/Screen) I guess, as we all use i1pros. LDVD gets better absolute results (on his PJ), and his settings are visually very close to mine. LG, probably because of the HP screen, shows undersaturated and dim by quite a large margin. It just shows that nothing replaces a calibration, even if someone else's settings can offer an improvement. But it can also me$$ things up no end.
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post #516 of 1634 Old 05-10-2009, 12:13 AM - Thread Starter
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Quote:
Originally Posted by darinp2 View Post

While I was measuring the primaries on my RS20 I was having some trouble measuring the blue primary. I ended up looking at the spectral curve in Calman and one thing it showed me is that the amount of red the tool was indicating for the blue primary (I think 100% level, but not positive) where I was aiming for REC.709 blue was about the same amount of red that it would indicate in a 30%stim gray image. The amount of signal the meter was reading in wavelengths in the green range was lower than it indicated for green in a 30% stim gray image. I should have saved images of those 2 spectral graphs so I could post them, but I didn't.

But for anybody using a spectroradiometer I think it could be interesting to look at what the spectral graph indicates is being read for levels of green and red while trying to adjust the blue primary, compared to what it reads at some different gray levels.

In my case I had put the projector about halfway to the screen with a smaller than normal image to try to get brighter images to hopefully help the accuracy of the measurements. I think my white level for this one was a little under 30 ft-lamberts.

--Darin

Thanks a lot for all the advice Darin, I'll try to use this for my next attempt.

What did you replace your RS-20 with? Just curious.
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post #517 of 1634 Old 05-10-2009, 12:58 AM
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Quote:
Originally Posted by Manni01 View Post

What did you replace your RS-20 with? Just curious.

I had both the Planar 8150 and RS20 before this and still have the 8150.

--Darin

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post #518 of 1634 Old 05-10-2009, 01:01 AM
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Quote:
Originally Posted by Lawguy View Post

I really broke in my i1Pro this morning.

I managed to get all colors, save blue, at dEs of under 2. Blue is very stubborn for me as it is very hard to influence its y. Did anyone else find this? Blue's dE is at 5.1.

These results track basically perfectly. I woudl love to revisit blue though.

In doing blue, I also plugged in lots of your numbers. Not only did they measure differently, they all look very different.

Here are my numbers:

r: 6,-30, 3
y: -6, -50, 33
g: -11, -47, 13
c: 40, -54, 29
b: 11, 8, -16
m: 8, -26, 10

I have not compared these to any of your settings but I wonder if there is any trend among them.

Thank you! I thought I was going crazy. I have been a long time member that does not post much (mostly lurk and read) but i am having the same problem. I cannot get a dE on blue under 6, but I can dial everything else in almost perfectly. I am seeing some of the others calibration results with a blue dE of under 1 and I just can't figure it out you are doing it.

I also wanted to add, I just purchased an i1 Pro with Calman software. I saw some people asking about this earlier. I will say, that as a beginner I found the Calman software difficult to use. I finally switched to HCFR, which it seems most use in this thread anyway, and found it much easier to use in conjunction with the greyscale and color calibration for dummies tutorial. It has been a great learning experience and I am learning so much more about my RS20- I highly recommend it.

Since I'm out of lurking mode, thanks to all of you that have posted, especially Manni and LDVD. I have gained a ton of knowledge from this thread and have enjoyed using some of your settings before I attempted my own calibration.
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post #519 of 1634 Old 05-10-2009, 01:08 AM - Thread Starter
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Quote:
Originally Posted by darinp2 View Post

I had both the Planar 8150 and RS20 before this and still have the 8150.

--Darin

Thanks Darin.
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post #520 of 1634 Old 05-10-2009, 01:13 AM
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Hi Manni,

hasn't it no problem on this point (under 100 %) ?




I'm sorry I can't open your (other) files, how is the "Y" (lightness) ?

A professional certified ISF said that it was (In his opinion), the more important issue with the first firmware (the variation on "Y" when he used the C.M.S.) ?
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post #521 of 1634 Old 05-10-2009, 01:16 AM - Thread Starter
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Quote:
Originally Posted by dneilan1 View Post

Thank you! I thought I was going crazy. I have been a long time member that does not post much (mostly lurk and read) but i am having the same problem. I cannot get a dE on blue under 6, but I can dial everything else in almost perfectly. I am seeing some of the others calibration results with a blue dE of under 1 and I just can't figure it out you are doing it.

I also wanted to add, I just purchased an i1 Pro with Calman software. I saw some people asking about this earlier. I will say, that as a beginner I found the Calman software difficult to use. I finally switched to HCFR, which it seems most use in this thread anyway, and found it much easier to use in conjunction with the greyscale and color calibration for dummies tutorial. It has been a great learning experience and I am learning so much more about my RS20- I highly recommend it.

Since I'm out of lurking mode, thanks to all of you that have posted, especially Manni and LDVD. I have gained a ton of knowledge from this thread and have enjoyed using some of your settings before I attempted my own calibration.

Welcome dneilan1, and no you're not crazy. I think Darin has given us a good lead, along with the fact that LDVD (one of those magicians who gets good results on blue) is calibrating from the PJ not from the screen.

Blue being the "darkest" color, the i1pro is probably challenged by it. Unfortunately it's not posible to use the trained d2 (which has better low light sensitivity) to adjust it, as the training remains only valid as long as the primaries are not changed.

Although I think that as long as you don't change x,y, we should be able to use a trained d2 to adjust blue's (or any other color) Y.

The alternative is to calibrate from the PJ like LDVD, but from what I read the difuser that comes with the D2/i1pro in order to do this is not very good.

LDVD, would you mind telling us more about the way you calibrate from the PJ, and which difuser you use?

Otherwise getting as much brightness as possible following Darin's advice seems to be the way forward.
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post #522 of 1634 Old 05-10-2009, 01:20 AM - Thread Starter
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Quote:
Originally Posted by Thebes View Post

Hi Manni,

hasn't it no problem on this point (under 100 %) ?




I'm sorry I can't open your (other) files, how is the "Y" (lightness) ?

A professional certified ISF said that it was (In his opinion), the more important issue with the first firmware (the variation on "Y" when he used the C.M.S.) ?

This is the 100% stim chart, so it's not as good as the 75% (which I used to calibrate).

All the data, including Y, is in the table above the CIE chart.

It's very easy to read the other files, just download HCFR (google download colorHCFR) and you will have access to them.

Yes Y was the main problem with the first firmware, it's absolutely fine now.
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post #523 of 1634 Old 05-10-2009, 02:17 AM
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Hi Manni,

I don't know why I can't open your files (I use the HCFR Software since many years ), but it's not important.

If I use your "pictures" (with the measure at 100 % and at 75 %) I obtain this :

It was not very important in absolute value, but in relative value ?

 

0k . file
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post #524 of 1634 Old 05-10-2009, 02:23 AM
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Quote:
Originally Posted by Manni01 View Post

Otherwise getting as much brightness as possible following Darin's advice seems to be the way forward.

I should add one thing. Derek (of SpectraCal) recommended not going over a specific amount for white with my EyeOne Beamer. I think it was around 100 ft-lamberts. I'm not sure how much this applies to the blue primary (like whether putting the projector even closer to the screen for that one, or the meter closer to the projector if measuring that way, would help).

--Darin

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post #525 of 1634 Old 05-10-2009, 02:24 AM - Thread Starter
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Quote:
Originally Posted by Thebes View Post

Hi Manni,

I don't know why I can't open your files (I use the HCFR Software since many years ), but it's not important.

If I use your "pictures" (with the measure at 100 % and at 75 %) I obtain this :

It was not very important in absolute value, but in relative value ?

The error on blue at 100% stim 100% sat I am aware of, and as I said this is not the stim level I have calibrated at. The error is less at 75% stim / 100% sat.

I don't know where you get the 75% saturation at 75% stim locations from, as I haven't measured them.

What you have in the pictures are 75% stim at 100% saturation, and 100% stim at 100% saturation. The 0%, 25% and 75% sat numbers are available in the 100% stim HCFR file.

Are you using the last version of HCFR? I'm using V2.1.
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post #526 of 1634 Old 05-10-2009, 02:30 AM - Thread Starter
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Quote:
Originally Posted by darinp2 View Post

I should add one thing. Derek (of SpectraCal) recommended not going over a specific amount for white with my EyeOne Beamer. I think it was around 100 ft-lamberts. I'm not sure how much this applies to the blue primary (like whether putting the projector even closer to the screen for that one, or the meter closer to the projector if measuring that way, would help).

--Darin

Thanks. I have the meter about 1-2 feet from the screen, because I find I get better repeatability for the greyscale when I am further away, but I may try to get closer when working on the gamut, and even try your trick of making the picture smaller, to maximise brightness on blue. Unless LDVD tells us he has found a reliable diffuser for the i1pro or another way to get reliable readings, I am not that keen on calibrating from the PJ.

At the moment my lamp is quite dim (around 8fL with iris at 0 on an 88" screen) so I am waiting to solve this problem before making another attempt with the gamut (esp blue) and fine-tuning my greyscale.
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post #527 of 1634 Old 05-10-2009, 02:32 AM
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Quote:
Originally Posted by Manni01 View Post

[...]
I don't know where you get the 75% saturation at 75% stim locations from, as I haven't measured them.

What you have in the pictures are 75% stim at 100% saturation, and 100% stim at 100% saturation. The 0%, 25% and 75% sat numbers are available in the 100% stim HCFR file.

[...].

Hi,

I use this (you calibration picture at 75 %, if I don't make a mistake, it's what I understand ) :

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post #528 of 1634 Old 05-10-2009, 02:33 AM - Thread Starter
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Quote:
Originally Posted by Thebes View Post

Hi,

I use this (you calibration picture at 75 %, if I don't make a mistake, it's what I understand ) :

This gives you 75% stim (brightness) at 100% sat, not 75% stim at 75% sat.
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post #529 of 1634 Old 05-10-2009, 02:48 AM
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Quote:
Originally Posted by Manni01 View Post

This gives you 75% stim (brightness) at 100% sat, not 75% stim at 75% sat.

Hi,

I'm confused, but the Y for the "white", it is not the Brightness ?

and it's not linked with the "Y" (and x and y) on primary and secondary "Y" ?

So, when, the "Y" white is at 16,29 at 75 % (against 28,8 at 100 %) the other color mustn't went on the relatives references ?

Sorry, maybe it's a mistake
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post #530 of 1634 Old 05-10-2009, 02:59 AM - Thread Starter
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Quote:
Originally Posted by Thebes View Post

Hi,

I'm confused, but the Y for the "white", it is not the Brightness ?

and it's not linked with the "Y" (and x and y) on primary and secondary "Y" ?

So, when, the "Y" white is at 16,29 at 75 % (against 28,8 at 100 %) the other color mustn't went on the relatives references ?

Sorry, maybe it's a mistake


Y for white is the brightness, but 75% white means 75% stimulus (brightness), not 75% saturation. So the relative percentages remain as far as stimulus is concerned (% of white), but the saturation for both values is 100%.

In the second table, you say it gives you results at 75% brightness and 75% saturation, which is data I haven't measured. So you are entering "imagined" data in the table.
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post #531 of 1634 Old 05-10-2009, 03:27 AM - Thread Starter
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LovingDVD, I had posted a confusing post that I have deleted by mistake when trying to edit it, probably for the better. So I'm going to ask the question differently.
I see that your results at 75% and 100% have been taken by the spyderII. Had you retrained the spyderII to the i1pro just prior to making these measurements? My understanding is that as training is only valid until the primaries (x,y) are changed, it can't be used to work on the gamut, only on the greyscale (where it makes sense to use a meter with better low light sensitivity like your Spyder or my D2LT, especially below 30IRE) and possibly on Y exclusively for the gamut.
So I am interested to find out why you would train the spyder II to make gamut measurements. Do you fine-tune brightness on the triky colors like blue with the trained spyderII once you have nailed x,y?
Also which diffuser do you use on the meters when calibrating from the PJ?
If you have a secret to get these dEs, we want to know it!
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post #532 of 1634 Old 05-10-2009, 04:32 AM
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Measure off the screen or from the projector but at the end of the day if the measurements off the screen are different, you have a problem.

I have no idea how much of an impact the screen has. I think there is some and when you add it together with unit to unit variation, it really makes a visible, if as Millerwill describes, small difference.

Affable Nitwit
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post #533 of 1634 Old 05-10-2009, 05:29 AM - Thread Starter
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Quote:
Originally Posted by Lawguy View Post

Measure off the screen or from the projector but at the end of the day if the measurements off the screen are different, you have a problem.

I have no idea how much of an impact the screen has. I think there is some and when you add it together with unit to unit variation, it really makes a visible, if as Millerwill describes, small difference.

There are three different points re the screen. 1) some screens are not neutral and have an effect on the colors. Both my carada bw and my centre stage xd are remarquably neutral, so that's not an issue, at least for me. 2) the gain has obviously an effect as you may want more or less brightness depending on the gain. 3) facing the screen means that you have less brightness, which brings the meter too close to its limits, especially on blue for example.
If you find a way to calibrate more accurately from the PJ, you can use screen offsets, both in calman and hcfr, to make sure it takes into account the color shift/brightness specificity of your screen. I have not used it yet, mainly because I've read that the diffusers coming with our meters are not good, therefore one should get better results from the screen.
Which is why I'd like to know how LDVD does it.
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post #534 of 1634 Old 05-10-2009, 08:36 AM
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I was wondering if you guys also do some visual checks after calibration. I mean: do you perform a color decoder check afterwards?

My CMS results (calibrated with I1 Lt, later this week my I1 pro will arrive) are very, very different from most settings I see on this thread, especially hue on red, green and blue, but they measure spot on (below delta error 2, below xy error 0.002 and below Y error 2%). Both on 75% and 100%.
Also the visual color decoder check (the 3 flashing RGB bars, the flashing RGB color brightness check and the RGB clipping check on the AVS HD disk) show no visible errors at all.
When I enter the values I see in this thread, both my measured and my visible results are completely off.

These are my CMS settings:
R 36, -23, 16
Y 8, -46, 36
G 24, -37, 28
C 4, -43, 34
B 36, -17, 10
M 8, -37, 25

Any thoughts about these huge differences?

*Edit may 16: Don't try the numbers above, they are not good. I've got a i1 Pro now and it seems my i1 D2 was a long way off.
LL
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post #535 of 1634 Old 05-10-2009, 08:50 AM
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When one starts to discuss 75% saturation, this has to mean "Chroma level". For example if you display a 75% SMPTE bar pattern, the signal (stimulus) is 75%. If you measure the White "Y", there will be a component of RGB that totals to the White "Y". If the blue component Y = 1.0, then, at the proper chroma level, the "Y" for the Blue bar should be 1.0. If the Blue "Y" = 0.75, the "color" control would be set to low causing it to under saturate the colors. All of the other colors in the pattern would be too low in "Y" as well. If they were not all 75% of expected "Y" values for their respective color, color decoding would be off (assuming the 100% x,y,Y values for White, Primaries and Secondaries are correct)

Glen Carter
Home Theater Calibration

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post #536 of 1634 Old 05-10-2009, 10:20 AM
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As far as I'm aware of, there are no sources for 75% Stim, 75% saturation patterns. The only patterns I'm aware of use 100% stim, but vary the saturation (chroma level). These are found on the AVSHD709 downloadable disc. These are the patterns I use for my calibrations. They are in the "saturation windows" menu option. For each of the primaries and secondaries, there are 0, 25%, 50%, 75% and 100% saturation (chroma level), but all are referenced to 100% Y, not 75% Y and assume a display gamma of 2.22.

I love the fact that these patterns exist because they have proven VERY useful for me.

Dan
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post #537 of 1634 Old 05-10-2009, 10:26 AM - Thread Starter
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Quote:
Originally Posted by stereomandan View Post

As far as I'm aware of, there are no sources for 75% Stim, 75% saturation patterns. The only patterns I'm aware of use 100% stim, but vary the saturation (chroma level). These are found on the AVSHD709 downloadable disc. These are the patterns I use for my calibrations. They are in the "saturation windows" menu option. For each of the primaries and secondaries, there are 0, 25%, 50%, 75% and 100% saturation (chroma level), but all are referenced to 100% Y, not 75% Y and assume a display gamma of 2.22.

I love the fact that these patterns exist because they have proven VERY useful for me.

Dan

Thanks for the confirmation Dan, these are the ones I use, and yes, I am not aware either of a source for a 75% stim set. Maybe Le Dahu can tell us, as he is the one who requested the data.
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post #538 of 1634 Old 05-10-2009, 10:29 AM
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Originally Posted by Thebes View Post

Hi Manni,

hasn't it no problem on this point (under 100 %) ?




I'm sorry I can't open your (other) files, how is the "Y" (lightness) ?

A professional certified ISF said that it was (In his opinion), the more important issue with the first firmware (the variation on "Y" when he used the C.M.S.) ?

It does look to me that that lower saturations are a little off. 75% saturation of red, green and yellow for example seem undersaturated versus the target points. This could be due to your gamma though. What gamma are you measuring?

Who's chart is this by the way? I'm a little confused. I'm not sure if Thebes was showing someone elses calibration results or his own.

Dan
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post #539 of 1634 Old 05-10-2009, 10:37 AM - Thread Starter
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Quote:
Originally Posted by stereomandan View Post

It does look to me that that lower saturations are a little off. 75% saturation of red, green and yellow for example seem undersaturated versus the target points. This could be due to your gamma though. What gamma are you measuring?

Dan

Even the 100% sat are undersaturated on my 100% stim measures. For some reason, this calibration didn't track as well as the last one, so I have to look at this. My gamma is not good, way too low, and like LDVD I find it tricky to adjust with the new firmware as it reads very differently.

As I said, this is unfortunately a temp calibration, as I'm still waiting to sort out my lamp issue. I'll start working on the greyscale/gamma when I'll know my lamp is here to stay, as this is quite time consuming.
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post #540 of 1634 Old 05-10-2009, 11:12 AM
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Quote:
Originally Posted by GlenC View Post

When one starts to discuss 75% saturation, this has to mean "Chroma level". For example if you display a 75% SMPTE bar pattern, the signal (stimulus) is 75%. If you measure the White "Y", there will be a component of RGB that totals to the White "Y". If the blue component Y = 1.0, then, at the proper chroma level, the "Y" for the Blue bar should be 1.0. If the Blue "Y" = 0.75, the "color" control would be set to low causing it to under saturate the colors. All of the other colors in the pattern would be too low in "Y" as well. If they were not all 75% of expected "Y" values for their respective color, color decoding would be off (assuming the 100% x,y,Y values for White, Primaries and Secondaries are correct)

What we are referring to as 75% saturation is much simpler than this. It is just distance from the white point. For example if red = x0.640, y0.330 and white = x0.3127, y0.329, then the distance between them is x0.3273, y0.001.

So 50% red saturation is 0.3127 + (.5 * 0.3273) for x and 0.329 +(.5 *0.001) for y or x0.476, y0.330. It is just half way from red to the white point in the Rec. 709 gamut. The Y value doesn't matter for the purpose of this measurement.

Tom Huffman
ChromaPure Software/AccuPel Video Signal Generators
ISF/THX Calibrations
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