Official JVC RS20 / HD750 Calibration and CMS thread (NEW FIRMWARE V1.1) - Page 19 - AVS Forum
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post #541 of 1634 Old 05-10-2009, 01:57 PM
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Quote:
Originally Posted by Marcel W View Post

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?


You've got some fairly big Hue adjustments in there. I spent five or six hours yesterday recalibrating and had to make some large Hue adjustments as well. When I measured the THX settings, my whole triangle was twisted clockwise a bit. Red was more towards magenta, green towards yellow, blue towards cyan. I dropped in lawguys' and lovingdvd's and ended up making changes to lovingdvd's settings as they were closer to being right. What really scares me is that I'm using an I1D2 and I don't have much confidence in it anymore. My grayscale looks good but I'm not so sure about the colors...

I was able to bump up my Green gain on the recalibration of the grayscale though, but I had much different settings for low bulb vs high bulb. I had to cut both green and blue a lot more in low bulb than in high. Jason originally calibrated my RS20 and the green gain was somewhere around -30ish on high bulb. When I recalibrated yesterday, I only needed green gain at -15.

I'm worried that the I1's may have problems on calibrating the color on these JVC's and I may be doing more harm than good. For those with good spectroradiometers, have you had to make big hue adjustments, or just pull in saturation and adjust brightness? If Hue was really incorrect, as my meter seems to suggest, would that show up when using the filters to adjust the color hue/tint from the DVE discs? If those don't show errors, are our meters reading wrong?

Absence of evidence is not evidence of absence

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post #542 of 1634 Old 05-10-2009, 02:14 PM
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Quote:
Originally Posted by Manni01 View Post

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, ....

Manni, The 'dummies guide' says to put the meter as close to the screen as possible, just a few inches from the pics they show. Have you confirmed with others about what you are suggesting here? Tx, Bill
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post #543 of 1634 Old 05-10-2009, 02:59 PM - Thread Starter
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Quote:
Originally Posted by millerwill View Post

Manni, The 'dummies guide' says to put the meter as close to the screen as possible, just a few inches from the pics they show. Have you confirmed with others about what you are suggesting here? Tx, Bill

I know this is what the dummies guide says, and this is what I've done for a while, but I could never get my greyscale measure the same twice, at least with the untrained d2. Then I read a post from one of the guys who made HCFR, who said he set his meter about 1-2 feet from the screen, and that he got better results with this.

I have to agree with him re greyscale, but it looks like this approach may be problematic with the gamut, especially on dark colors like blue, and even more when your brightness is borderline.

Frankly my lamp is to dim now to do anything useful, so I'm waiting to have this sorted to try to improve things further.
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post #544 of 1634 Old 05-10-2009, 03:02 PM
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Quote:
Originally Posted by mrlittlejeans View Post

I'm worried that the I1's may have problems on calibrating the color on these JVC's and I may be doing more harm than good. For those with good spectroradiometers, have you had to make big hue adjustments, or just pull in saturation and adjust brightness? If Hue was really incorrect, as my meter seems to suggest, would that show up when using the filters to adjust the color hue/tint from the DVE discs? If those don't show errors, are our meters reading wrong?

From what I have seen, the errors in the RS20 gamut are almost exclusively in saturation. Hues are off by only a very little and the lightness values are also very close to correct. However, you must get the grayscale right first. Here's what I am seeing from User 1 after grayscale calibration but before CMS calibration:

R G B Y C M
L 1.5% -0.4% -5.8% 0.0% -0.7% 0.1%
S 12.6% 22.6% 5.9% 17.2% 24.0% 7.1%
H -1.0% 2.3% -1.9% 1.4% -10.0% 4.5%

Negative values indicate clockwise errors in hue and positive values indicate counterclockwise errors.

Tom Huffman
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post #545 of 1634 Old 05-10-2009, 03:12 PM
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Quote:
Originally Posted by Manni01 View Post

I know this is what the dummies guide says, and this is what I've done for a while, but I could never get my greyscale measure the same twice, at least with the untrained d2. Then I read a post from one of the guys who made HCFR, who said he set his meter about 1-2 feet from the screen, and that he got better results with this.

I have to agree with him re greyscale, but it looks like this approach may be problematic with the gamut, especially on dark colors like blue, and even more when your brightness is borderline.

The only difference in closer vs. farther is the aim point. Close readings measure higher luminance but over a smaller area. Farther away the level is lower but the area of the screen from which you read is larger. These two factors cancel each other out, so from the standpoint of the final luminance reading it shouldn't make a difference. A couple of feet away sounds about right to me. The angle of acceptance of these meters is fairly large so the viewing cone gets bigger fairly quickly as you move away from the screen, which makes getting an accurate aim point more difficult.

BTW, this is one of the advantages of high-end meters. They generally have either a lens or a spot laser that defines the area from which the device reads and a narrow angle of acceptance, which makes getting a good aim point easier and more precise.

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post #546 of 1634 Old 05-10-2009, 03:24 PM
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OK, thanks Manni and Tom. I will try to do my grayscale with my I1LT 1 to 2 ft from the screen. I want to get the grayscale as best I can on my own before UMR arrives to do this magic--to see how far wrong I am even trying my best!
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post #547 of 1634 Old 05-10-2009, 04:07 PM
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Quote:
Originally Posted by TomHuffman View Post

From what I have seen, the errors in the RS20 gamut are almost exclusively in saturation. Hues are off by only a very little and the lightness values are also very close to correct. However, you must get the grayscale right first. Here's what I am seeing from User 1 after grayscale calibration but before CMS calibration:

R G B Y C M
L 1.5% -0.4% -5.8% 0.0% -0.7% 0.1%
S 12.6% 22.6% 5.9% 17.2% 24.0% 7.1%
H -1.0% 2.3% -1.9% 1.4% -10.0% 4.5%

Negative values indicate clockwise errors in hue and positive values indicate counterclockwise errors.

The strange thing in my case, however, is that although I have to make these big adjustments in hue, the visible result (eyeballing with R,G and B glasses to the different hue and color decoder checks) is 100% perfect!
Same goes for grayscale, by the way. That's excellent as well.

On one side, I am not 100% sure about the I1 LT, but on the other side: if things were off, it really should show with the visual color decoding checks and hue bars. And that is not happening.

As Mrlittlejeans remarked: measuring THX and most settings from others, results in a clockwise tilted triangle.

Well, I hope my I1 pro will arrive soon to put an end to my doubts.
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post #548 of 1634 Old 05-10-2009, 04:45 PM
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Quote:
Originally Posted by Manni01 View Post

Frankly my lamp is to dim now to do anything useful, so I'm waiting to have this sorted to try to improve things further.

Is this your new lamp that has gone dim now Manni?

I've have given up with using my I1-LT as I found that I can't repeat any readings with a reasonable accuracy even on my TV which I can't imagine will drift that much once warmed up. I can get a greyscale within a delta of 2 using my Lumagen to adjust, but if I check it the next day it has a delta of 5 or more. I don't know which reading to trust, so I've cleared the greyscale adjustments in the HDQ and I'm just getting on enjoying films as it is.

I might consider an ISF calibration as I've reached 100+hours (and I'm not looking for my next PJ either ).

Zooming: Been there, done that, bought the lens...
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post #549 of 1634 Old 05-10-2009, 09:20 PM
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Quote:
Originally Posted by TomHuffman View Post

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.

In digital terms, white is R,G,B=235, black is R,G,B=0. If you want a color that resides half way on the line between white and Red, your signal would be R=235, G=125.5, B=125.5. There is no "calibration basis" AFAIK, for needing a color measurement with "75% saturation" as you describe.

If the gamma tracking for each of the three primaries is accurate, then all derived colors should be "OK" provided there are no decoding errors. We all know this doesn't happen in reality. To get to the 50% color you described does involve "Y" because it is derived from a combination of all three colors.

If the REC 709 colorspace tends to collapse or expand as stimulus levels change, those are CMS issues, generally not fixable. We just need to derive a useable compromise.

As you try to correct "Red" to REC 709, you add Blue and Green to affect Hue, but the additional amounts of B/G affect "Y" (saturation/color). As you get close, the filters will look good for decoding, measurements are required to verify properly.

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post #550 of 1634 Old 05-11-2009, 05:17 AM - Thread Starter
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Originally Posted by Marcel W View Post

Well, I hope my I1 pro will arrive soon to put an end to my doubts.

If you're like Lawguy and myself, don't bet on this.
Although in the end, the doubts do go...
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post #551 of 1634 Old 05-11-2009, 05:21 AM - Thread Starter
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Quote:
Originally Posted by TomHuffman View Post

The only difference in closer vs. farther is the aim point. Close readings measure higher luminance but over a smaller area. Farther away the level is lower but the area of the screen from which you read is larger. These two factors cancel each other out, so from the standpoint of the final luminance reading it shouldn't make a difference. A couple of feet away sounds about right to me. The angle of acceptance of these meters is fairly large so the viewing cone gets bigger fairly quickly as you move away from the screen, which makes getting an accurate aim point more difficult.

BTW, this is one of the advantages of high-end meters. They generally have either a lens or a spot laser that defines the area from which the device reads and a narrow angle of acceptance, which makes getting a good aim point easier and more precise.

Thanks Tom. I think it is from you that I read you had doubts about the quality of the diffusers coming with the d2. Is it the same with the i1pro? If one has problems with blue, would you recommend trying to measure from the PJ with the diffuser (either stock or replacement), or would you try to maximise brightness by zoooming out to get a smaller/brighter picture while you calibrate? Also, on a PJ, would you use fields instead of windows to have a larger lit area, or does this lower the brigthness?
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post #552 of 1634 Old 05-11-2009, 05:22 AM
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Quote:
Originally Posted by TomHuffman View Post

From what I have seen, the errors in the RS20 gamut are almost exclusively in saturation. Hues are off by only a very little and the lightness values are also very close to correct. However, you must get the grayscale right first. Here's what I am seeing from User 1 after grayscale calibration but before CMS calibration:

R G B Y C M
L 1.5% -0.4% -5.8% 0.0% -0.7% 0.1%
S 12.6% 22.6% 5.9% 17.2% 24.0% 7.1%
H -1.0% 2.3% -1.9% 1.4% -10.0% 4.5%

Negative values indicate clockwise errors in hue and positive values indicate counterclockwise errors.

These values give some support to my larger Hue correction for Cyan. In fact, putting aside Y values (which will be affects by Saturation adjustments), all of your measures, with the exception of blue, seem to correspond with my CMS values.

What do you do for blue? I simply could no influence its "y" without extreme adjustments and even then, I could never get it close to correct.

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post #553 of 1634 Old 05-11-2009, 05:23 AM
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Quote:
Originally Posted by Manni01 View Post

If you're like Lawguy and myself, don't bet on this.
Althogh in the end, the doubts do go...

What that cheap thing? It's like a toy meant for children and is to be used stricty for fingerpainting color-correction purposes.

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post #554 of 1634 Old 05-11-2009, 05:26 AM
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Originally Posted by Bulldogger View Post

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

Feel free to PM me if you need any help. I don't promise to know the answer though!

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post #555 of 1634 Old 05-11-2009, 05:27 AM - Thread Starter
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Originally Posted by Lawguy View Post

What that cheap thing? It's like a toy meant for children and is to be used stricty for fingerpainting color-correction purposes.

Don't mention it, I tried to give it to my three year old daughter and even she wouldn't touch it... "not accurate enough" she said.
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post #556 of 1634 Old 05-11-2009, 05:34 AM - Thread Starter
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Quote:
Originally Posted by Kelvin1965S View Post

Is this your new lamp that has gone dim now Manni?

I've have given up with using my I1-LT as I found that I can't repeat any readings with a reasonable accuracy even on my TV which I can't imagine will drift that much once warmed up. I can get a greyscale within a delta of 2 using my Lumagen to adjust, but if I check it the next day it has a delta of 5 or more. I don't know which reading to trust, so I've cleared the greyscale adjustments in the HDQ and I'm just getting on enjoying films as it is.

I might consider an ISF calibration as I've reached 100+hours (and I'm not looking for my next PJ either ).

My new lamp was only 30% brighter than the old one at 500 hours (and 50% less bright than the old one at 185 hours). So it looks like I've been unlucky, and I'm waiting for a "new" new one.
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post #557 of 1634 Old 05-11-2009, 09:09 AM
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Quote:
Originally Posted by Manni01 View Post

Thanks Tom. I think it is from you that I read you had doubts about the quality of the diffusers coming with the d2. Is it the same with the i1pro? If one has problems with blue, would you recommend trying to measure from the PJ with the diffuser (either stock or replacement), or would you try to maximise brightness by zoooming out to get a smaller/brighter picture while you calibrate? Also, on a PJ, would you use fields instead of windows to have a larger lit area, or does this lower the brigthness?

You can always compensate for whatever effect the diffuser has by using an offset, but that assumes you have a valid off-the-screen reading to begin with, which I gather is precisely the problem, at least with blue.

Blue can be a pain because it is so dim. I think that your suggestion of using zoom to get a smaller, brightner area to read from is a good one. Assuming you have verified that the RS20 is linear from 75% to 100% stim (I haven't checked this yet), then use 100% test patterns. The combination of these two strategies should allow you to get a good off-the-screen reading without resorting to a diffuser.

Using fields is probably a good idea for this type of display if for no other reason than it eliminates problems with the aim point. The difference in brightness should be minimal. You will see a small difference because fields throw a lot more light into the room, which then reflects back onto the screen.

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post #558 of 1634 Old 05-11-2009, 09:13 AM
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Originally Posted by Lawguy View Post

What do you do for blue? I simply could no influence its "y" without extreme adjustments and even then, I could never get it close to correct.

I didn't have any problem with blue. The i1Pro's poor low-light sensitivity may cause problems trying to get a valid reading for blue. I can only suggest the same things I did to Manni: use 100% patterns, full fields, and zoom the image down to make it smaller and brighter.

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post #559 of 1634 Old 05-11-2009, 09:20 AM - Thread Starter
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Quote:
Originally Posted by TomHuffman View Post

You can always compensate for whatever effect the diffuser has by using an offset, but that assumes you have a valid off-the-screen reading to begin with, which I gather is precisely the problem, at least with blue.

Blue can be a pain because it is so dim. I think that your suggestion of using zoom to get a smaller, brightner area to read from is a good one. Assuming you have verified that the RS20 is linear from 75% to 100% stim (I haven't checked this yet), then use 100% test patterns. The combination of these two strategies should allow you to get a good off-the-screen reading without resorting to a diffuser.

Using fields is probably a good idea for this type of display if for no other reason than it eliminates problems with the aim point. The difference in brightness should be minimal. You will see a small difference because fields throw a lot more light into the room, which then reflects back onto the screen.

Thanks Tom, I'll try this. The zooming suggestion comes from Darin really, and it makes sense. Linearity seems to be a bit impredictable. It's never as bad as with the old firmware, but it seems to fluctuate from near perfect to not so good, and I haven't isolated the cause yet.
I'll try again to calibrate at 100% with zoomed full field patterns, it may help with blue indeed.
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post #560 of 1634 Old 05-11-2009, 09:30 AM
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Originally Posted by TomHuffman View Post

I didn't have any problem with blue. The i1Pro's poor low-light sensitivity may cause problems trying to get a valid reading for blue.

I think this is right. When I took constant readings, blue's numbers jumped around quite a bit. I'll try zooming in. Great idea.

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post #561 of 1634 Old 05-11-2009, 09:32 AM
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Originally Posted by mrlittlejeans View Post

You've got some fairly big Hue adjustments in there...

I did too when I calibrated with my i1LT. I no longer do with my i1Pro. My largest is on Cyan, which Tom's measurments confirm has a hue issue.

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post #562 of 1634 Old 05-11-2009, 09:47 AM
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mrlittlejeans' and Tom's comments on Hue made me sit down and compare my old i1LT calibration to my i1Pro calibration setting. They are actually very close. The biggest difference in colors other than blue is in the Hue settings. I don't know what to make of blue.

i1LT Calibration

r: 9, -26, -2
y: -6, -52, 34
g: -32, -48, 11
c: 49, -60, 29
b: 60, 34, -21
m: 0, -27, 1

i1Pro Calibration

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

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post #563 of 1634 Old 05-11-2009, 09:47 AM
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Quote:
Originally Posted by GlenC View Post

In digital terms, white is R,G,B=235, black is R,G,B=0. If you want a color that resides half way on the line between white and Red, your signal would be R=235, G=125.5, B=125.5.

This is what I once assumed as well, but because of gamma actually it is a little different. Using % values it is approximately R100%, G46%, B46%.

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Originally Posted by GlenC View Post

There is no "calibration basis" AFAIK, for needing a color measurement with "75% saturation" as you describe.

There can be and you allude to it later in your post. If the colorspace is not linear in that different levels of saturation do not fall where they should on the CIE chart, then compromises need to be made. Stereomandan has done some good work in this regard. It's not a problem with the RS20, but my Sharp 20K is very non-linear in this regard. When I get a fully saturated red correctly calibrated then all of the less saturated reds are significantly off from where they should be in the color space. Thus, I get better measured performance throughout the color space by allowing a little oversaturation at its edge.

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Originally Posted by GlenC View Post

To get to the 50% color you described does involve "Y" because it is derived from a combination of all three colors.

Any color involves Y. It is part of how a color is defined. What I meant was that for the purpose of checking saturations, it doesn't matter how bright the red is. All that matters is where it falls on the CIE chart. The disc-based test patterns out there use constant brightness for the range of saturations, even though, all else being equal, if you simply reduce red's saturation and move it towards the white point, e.g., R100%, G46%, B46% it becomes brighter. Keeping constant brightness is a harmless methodological choice.

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post #564 of 1634 Old 05-11-2009, 09:51 AM
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Quote:
Originally Posted by Lawguy View Post

mrlittlejeans' and Tom's comments on Hue made me sit down and compare my old i1LT calibration to my i1Pro calibration setting. They are actually very close. The biggest difference in colors other than blue is in the Hue settings. I don't know what to make of blue.

It is quite possible that--again because of its poor low-light sensitivity--you are getting a LESS accurate reading of blue with the i1Pro than you were with the D2.

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post #565 of 1634 Old 05-11-2009, 10:00 AM
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Originally Posted by TomHuffman View Post

It is quite possible that--again because of its poor low-light sensitivity--you are getting a LESS accurate reading of blue with the i1Pro than you were with the D2.

That may very well be.

I adjust the CMS settings with the constant read feature on, but I always run full a set (or sets) of numbers using the gamut measuring function in which ColorHCFR, presumably averages many reads to improve accuracy for low light readings. I can tell it takes a long time when measuring bue.

Thanks Tom for sharing what you know about this. I feel I have come a long way in appreciating accurate color and it is in many ways thanks to you being such a persistent advocate.

Affable Nitwit
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post #566 of 1634 Old 05-11-2009, 10:13 AM - Thread Starter
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Originally Posted by Lawguy View Post

That may very well be.

I adjust the CMS settings with the constant read feature on, but I always run full a set (or sets) of numbers using the gamut measuring function in which ColorHCFR, presumably averages many reads to improve accuracy for low light readings. I can tell it takes a long time when measuring bue.

Thanks Tom for sharing what you know about this. I feel I have come a long way in appreciating accurate color and it is in many ways thanks to you being such a persistent advocate.

LG, HCFR only averages many reads if you specifically check the option in HCFR (menu measures/sensor). Otherwise it doesn't.
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post #567 of 1634 Old 05-11-2009, 10:19 AM
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Originally Posted by Manni01 View Post

LG, HCFR only averages many reads if you specifically check the option in HCFR (menu measures/sensor). Otherwise it doesn't.


I had it checked in my most recent calibration.

If anyone is interested in analyzing data sets, here are all the calibrations that we have to date. Any common denominators?


Marcel W

R 36, -23, 16
Y 8, -46, 36
G 24, -37, 28
C 4, -43, 34
B 36, -17, 10
M 8, -37, 25

Lawguy i1LT Calibration

r: 9, -26, -2
y: -6, -52, 34
g: -32, -48, 11
c: 49, -60, 29
b: 60, 34, -21
m: 0, -27, 1

Lawguy i1Pro Calibration

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

Manni (1.2 gain screen)

R=-4 -22 6
Y=9 -45 38
G=-4 -44 35
C=-2 -51 43
B=0 -20 4
M=1 15 7

Manni (1.4 Gain Screen)

R= -4 -22 3
Y=6 -46 37
G=-11 -43 31
C=-3 -51 39
B=30 0 -7
M=1 0 -5

Lovingdvd

R 2 -24 10
Y 3 -44 34
G -10 -42 32
C -2 -48 38
B 0 -25 9
M 2 -31 16

JeffY

R -4,-22,11
Y 5,-44,37
G -6,-42,35
C -2,-46, 37
B 6, -4, 3
M -2,-4,0

Karrih

R 16,-27, 12
Y 6, -48, 37
G 5, -45, 39
C 2, -49, 39
B 36, -18, 4
M 1, -30, 15

008

R; 3 -22 9
Y; 6 -44 37
G; 15 -37 27
C; 2 -43 35
B; 26 -5 -3
M; 5 -22 12

Nelson4u

Red -3 -22 6
yellow 2 -48 39
green -19 -45 35
cyan 1 -52 44
blue 11 -25 10
magenta -5 -29 14

Ignace

Red 6 -29 8
Yellow 1 -48 35
Green -24 -46 33
Cyan 8 -56 43
Blue 18 -24 8
Magenta -10 -32 15

Affable Nitwit
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post #568 of 1634 Old 05-11-2009, 10:30 AM - Thread Starter
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^glad to see someone found a use for my first post recap
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post #569 of 1634 Old 05-11-2009, 11:02 AM
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Originally Posted by Manni01 View Post

My new lamp was only 30% brighter than the old one at 500 hours (and 50% less bright than the old one at 185 hours). So it looks like I've been unlucky, and I'm waiting for a "new" new one.

I hope you are just 'unlucky' however, I'd be tempted to ask them to look at the circuitry that powers the lamp incase there is an issue with it not allowing the correct current/voltage to the lamp. It's a shame you're some distance from me otherwise you'd be welcome to try swapping lamps to see how bright yours is in mine & visa versa. I've got 110 hours or so on mine and I'm still mainly using iris at 13 (service menu tweak for the HD350 ) and low lamp on a 112" wide 2.35:1 screen 1.5 (claimed) gain.

Zooming: Been there, done that, bought the lens...
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post #570 of 1634 Old 05-11-2009, 11:13 AM - Thread Starter
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Originally Posted by Kelvin1965S View Post

I hope you are just 'unlucky' however, I'd be tempted to ask them to look at the circuitry that powers the lamp incase there is an issue with it not allowing the correct current/voltage to the lamp. It's a shame you're some distance from me otherwise you'd be welcome to try swapping lamps to see how bright yours is in mine & visa versa. I've got 110 hours or so on mine and I'm still mainly using iris at 13 (service menu tweak for the HD350 ) and low lamp on a 112" wide 2.35:1 screen 1.5 (claimed) gain.

Thanks for the kind offer. It's true it could be something else, but as the first lamp had full brightness (or close), it's likely to be just the replacement lamp that was below specs.
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