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Old 09-20-2008, 07:43 AM
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For specking projectors upon which one could make meaning buying comparisons, the measuring room should be eliminated if possible. so measure ANSI CR through the lens. Now for poses of PQ in any particular theater, the measurement should include the room. What you see. Of course who needs measurments in the room, just post a screen shot.
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Old 09-20-2008, 08:18 AM
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Quote:
Originally Posted by mark haflich View Post

Of course a CRT can't meet the DCI color standard. but the DCI standard would be better and different if digitals could do some things better that CRTs can do.

I also DID find out however that the G90 CAN MEET the SMPTE standard WITHOUT CHANGING THE C ELEMENT on GREEN.

I'm going to need a bit more time on this one as I'm waiting for a certain feature from a certain video processor.

Now, as far as the DCI spec, well, after talking to Ken, for me, it's meaningless.

I could care less about the spec at this time and I'm sure I will have ABSOLUTELY NO use for it in the next couple of years. If by chance even ONE movie is filmed and encoded in DCI specification and released, that does not compare to the entire catalogue available now even on say Blue Ray that DOES NOT use the spec.

I'm sure eventually that there will be a day when I want a projector that can meet it but it's not going to be anytime soon.

I sure as hell do hope though that projector manufacturers are PAYING ATTENTION and can make a projector THAT DOES BOTH BLACK AND WHITE good.

When I say good, I mean G90 STACK good and NOT RS2 GOOD.

Cliffy
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Old 09-20-2008, 08:35 AM
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Of course it can.But at what cost in brightness reduction or on tube wear to get sufficient brightness. don't tyake this wrong. I have a CRT (only one) too.
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Old 09-20-2008, 08:35 AM
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Quote:
Originally Posted by mark haflich View Post

For specking projectors upon which one could make meaning buying comparisons, the measuring room should be eliminated if possible. so measure ANSI CR through the lens. Now for poses of PQ in any particular theater, the measurement should include the room. What you see. Of course who needs measurments in the room, just post a screen shot.



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Old 09-20-2008, 08:37 AM
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Quote:
Originally Posted by mark haflich View Post

Of course it can.But at what cost in brightness reduction or on tube wear to get sufficient brightness. don't tyake this wrong. I have a CRT (only one) too.

Mark, I'll lose a WHOLE foot lambert, so roughly 10 percent.

Cliffy
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Old 09-20-2008, 10:11 AM
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Right but you have a stack. I get about 7 ft lamberts with my superior to a G90 highly modified 9500 LC ultra with green and red C elements. You are getting 5 ft lamberts from your err light canons. Any 10% loss with a non stack 5 ft lamberts would be highly undesiriable.
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Old 09-20-2008, 10:29 AM
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Quote:
Originally Posted by overclkr View Post

I also DID find out however that the G90 CAN MEET the SMPTE standard WITHOUT CHANGING THE C ELEMENT on GREEN. ...

Why are you concerned about DCI? The question is can you get correct Rec 709 (HD) and SMPTE C (SD) colors with acceptable brightness levels.

Anyway this is the AVS Contrast thread right?
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Old 09-20-2008, 10:51 AM
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The reason to think about a color gamut larger than Rec 709 is the coming availability of enhanced content that may have a color gamut very close to DCI. Unfortunately, the only way to get a G90 closer to either SMPTE C or Rec 709 is through filtration. If you match Rec 709 and have a good CMS, you can also get to SMPTE C. You can even get to DCI, but the light loss would be unacceptable. However, the first step is getting more saturated primaries, especially green, and that requires filters. CMS can only give you less saturated primaries.
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Old 09-20-2008, 11:59 AM
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It may be coming but it has a long way to go. Expensive server and expensive content if it gets here. Seeing it demoed at the Cedia Expo did not demonstrate hugh gains in image. Better yes but I wouldn't worry about it now.
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Old 09-20-2008, 12:53 PM
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Odyssey. I believe you are correct but this not going to let my friend Cliffy sleep any better.
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Old 09-20-2008, 08:47 PM
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Quote:
Originally Posted by mark haflich View Post

Right but you have a stack. I get about 7 ft lamberts with my superior to a G90 highly modified 9500 LC ultra with green and red C elements. You are getting 5 ft lamberts from your err light canons. Any 10% loss with a non stack 5 ft lamberts would be highly undesiriable.

Hmmmmm, I'm gonna have to ask you to please send me that Marquee for a up close and personal evaluation next to one of my G90's.

That's why I stacked BTW.

So basically I will drop down to 9 foot lamberts and my tubes have not lost an ounce of light in 3000 hours. The green gains have stayed exactly where they have been since day one. 220.

To give you guys an idea, the RS1 at supposed (I have not measured with the minolta) 15K to one on off, measured 8 foot lamberts on my screen with a brand new bulb when Don Kellogg was gracious enough to bring his over.

Now imagine another foot lambert with a MEASURED 200K to one on off at 10ft wide unity gain?


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Old 09-20-2008, 08:52 PM
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Quote:
Originally Posted by HoustonHoyaFan View Post

Why are you concerned about DCI? The question is can you get correct Rec 709 (HD) and SMPTE C (SD) colors with acceptable brightness levels.

Anyway this is the AVS Contrast thread right?

Yes, and I will jump off of the colors now unless what I state is actually not able to happen.

I also hope to soon get that minolta back in here to answer some of the other questions and that way we can FINALLY have measured numbers to put down in history in regards to the G90 (stack) for all contrast levels.

I did however discover with Ken like I've said before, I really need to treat my room to be a black hole for it to really give you that WOW factor. I'm going to black cloth my entire room. It will be a bit before I get it done, but I know that it will make a SERIOUS marked improvement over what I'm getting now.

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Old 09-20-2008, 08:54 PM
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Quote:
Originally Posted by odyssey View Post

The reason to think about a color gamut larger than Rec 709 is the coming availability of enhanced content that may have a color gamut very close to DCI. Unfortunately, the only way to get a G90 closer to either SMPTE C or Rec 709 is through filtration. If you match Rec 709 and have a good CMS, you can also get to SMPTE C. You can even get to DCI, but the light loss would be unacceptable. However, the first step is getting more saturated primaries, especially green, and that requires filters. CMS can only give you less saturated primaries.

I'm being told 100% different right now, and I'll drop it for now like I said, but, I'm being told different.

Cliff
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Old 09-20-2008, 09:07 PM
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Quote:
Originally Posted by overclkr View Post

I did however discover with Ken like I've said before, I really need to treat my room to be a black hole for it to really give you that WOW factor. I'm going to black cloth my entire room. It will be a bit before I get it done, but I know that it will make a SERIOUS marked improvement over what I'm getting now.

I recall that Guy Kuo did something like that when he had an LC NEC projector and he said that after doing that he discovered it was the projector that was really the big ANSI CR culprit. What color is your room now? Going darker may have other advantages like the walls disappearing in the portion of the room you can see while watching things. That is basically how my room is (black velvet on the walls, floor, and ceiling for most of the room and all of the front half).

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Old 09-20-2008, 09:08 PM
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Quote:
Originally Posted by overclkr View Post

To give you guys an idea, the RS1 at supposed (I have not measured with the minolta) 15K to one on off, measured 8 foot lamberts on my screen with a brand new bulb when Don Kellogg was gracious enough to bring his over.

Now imagine another foot lambert with a MEASURED 200K to one on off at 10ft wide unity gain?

I'm curious about 30k:1 on/off CR with possibly more ft-lamberts than the RS1 and 300:1+ ANSI CR from an RS20. I'm wondering if an RS20 with the iris open or close to open and near the short end of the throw would have a white level close to the 2 G90s. Of course, the bulb will dim faster than the tubes, but I would love to hear about it if somebody brought an RS20 over. I'm curious about how the sharpness would compare between the RS20 and the 2 G90s for one thing.
Quote:
Originally Posted by overclkr View Post

I did however discover with Ken like I've said before, I really need to treat my room to be a black hole for it to really give you that WOW factor. I'm going to black cloth my entire room. It will be a bit before I get it done, but I know that it will make a SERIOUS marked improvement over what I'm getting now.

I recall that Guy Kuo did something like that when he had an LC NEC projector and he said that after doing that he discovered it was the projector that was really the big ANSI CR culprit. What color is your room now? Going darker may have other advantages like the walls disappearing in the portion of the room you can see while watching things. That is basically how my room is (black velvet on the walls, floor, and ceiling for most of the room and all of the front half).

--Darin

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Old 09-20-2008, 09:22 PM
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Quote:
Originally Posted by darinp2 View Post

I'm curious about 30k:1 on/off CR with possibly more ft-lamberts than the RS1 and 300:1+ ANSI CR from an RS20. I'm wondering if an RS20 with the iris open or close to open and near the short end of the throw would have a white level close to the 2 G90s. Of course, the bulb will dim faster than the tubes, but I would love to hear about it if somebody brought an RS20 over. I'm curious about how the sharpness would compare between the RS20 and the 2 G90s for one thing.

--Darin

Ok big dog, who we gonna get to send me one.

Oh, and are you going to fly out to compare?

Quote:
Originally Posted by darinp2 View Post

Going darker may have other advantages like the walls disappearing in the portion of the room you can see while watching things. That is basically how my room is (black velvet on the walls, floor, and ceiling for most of the room and all of the front half).

--Darin

Exactly. Those projectors light up my room really good and the only thing I think would stop it is to go black fabric. I too would be curious to see if this affected my ANSI. I have one idea though that I know could definitely help in that department.

Ken and I both discussed last night now much it would improve if I made a black hole like yours. :^)

Cliffy
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Old 09-21-2008, 07:11 AM
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Mark (me) will lend you one (an RS20) for a few days when he gets one. Two.  I'll just have my wife take down the 9500LC ultra and you can send your wife over to pick it up. I'll hold the door.

I haven't been able to reach Ken in awhile. I am going to SU on 10/22 through 10/24. I will fly in to Omaha on10/21 and drive to SU in SF, SD. The course starts at 8 AM 10/22. A political campaign requires me to be in SC, Iowa on the 25th through early November, 81miles due south from SF, SD. but I could drive Ken back to Omaha the night of the 22. I need to make plane reservations very soon.

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Old 09-21-2008, 10:47 AM
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Quote:
Originally Posted by mark haflich View Post

Mark (me) will lend you one (anRS20) for a few days when he gets one. Two.I just have my wife take down the 9500LC ultra and you send your wife over to pick it up. I'll hold the door.

I haven't been able to reach Ken in awhile. I am going to SU on 10/22 through 10/24. I will fly in to Omaha on10/21 and drive to SU in SF, SD. The course starts at 8 AM 10/22. A political campaign requires me to be in SC, Iowa on the 25th through early November,81miles due south from SF,SD. but I could drive Ken back to Omaha the night of the 22. I need to make plane reservations very soon.

Sweet bro, looking foward to checking it out! When are they supposed to ship? I wonder if I could stack them.

So are you and Ken going to go together?

Cliff
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Old 09-21-2008, 11:41 AM
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You really can't do stack because you can't line the pixels up. You can't adjust geometry like you can on a CRT.

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Old 10-23-2012, 10:47 AM
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Sorry for necro revival but I really wanted to post this.
Quote:
Originally Posted by Otto J View Post

I have a thought about contrast, that I'd like to share with you - I don't quite know where to put it, but I guess it fits into this discussion, although it isn't directly related to the issue of ANSI vs. on/off:


I believe the whole concept of stating contrast as a ratio to one is wrong. It's an absolute scale, but our eyes (and ears) don't work in absolute terms, they behave more like a logarithmic scale. Because of this, I believe that the percieved differences in contrast between two displays doesn't relate very well to the numbers of the measured contrast ratios. Talking about on/off contrast, the difference between 500:1 and 1000:1 isn't the same percieved difference as 1000:1 to 1500:1. And certainly, 10.000:1 and 15.000:1 isn't a very important difference, compared to 500:1 and 1000:1. The higher contrast ratio we have, the more it needs to increase for us to percieve a difference. I know this is a PJ forum, but it's certainly an issue with the ridicuously increasing marketing contrast numbers in future LCD displays - if Sharp has a panel with 1 million to 1, isn't it much better than Samsung's 100.000:1? Well, no, almost impossible to percieve (if it were true).


I'm comparing to sound pressure level. dB is a relative scale, just like contrast ratio. Sound pressure level could just as well be labelled as a ratio to one, instead of dB - it's two ways of saying the same thing (except for one being a fixed level in audio terms). I would think that a dB scale for contrast would more closely relate to what we actually percieve, at least in some psychological way:


2:1 = 3 dB

10:1 = 10 dB

100:1 = 20 dB

500:1 = 27 dB

1000:1 = 30 dB

2000:1 = 33 dB

4000:1 = 36 dB

10.000:1 = 40 dB

20.000:1 = 43 dB

etc.


Psychologically, this would mean that it doesn't make much difference if the screen has 40 or 43 dB, but it certainly does make a difference if it has 30 or 40 dB.


Am I way out of whack on this thought? Of course, it still doesn't solve anything about the issue of the way contrast is measured, but at least it would make the numbers more closely related to the way we actually percieve differences in contrast? Perhaps?
This guy had a really good point. The contrast measurements we use is an absolute scale, i.e. 1000:1, 5000:1, 20000:1 contrast etc. But we can't say that 30000:1 is perceptially 2x times better than 15000:1 for example, because our perception is logarithmic. In sound they use a relative scale to measure loudness - dB. It is widely known that a 3dB increase is perceptially 2x times louder. You may use 3*log2(X) formula to convert contrast numbers to dB.

So here's a simple forumla for you to determine how contrast A measures against contrast B perceptionally:

log2(Contrast A)
________________
log2(Contrast B)


You can easily calculate it in Excel. For example, contrast ratio of 8192:1 is better than 1024:1 mathematically by 800% but perceptionally only by 30%. To double the perceivable contrast you have to get 1048576:1 contast. wink.gif

There's more. Drawing parallels we can remember equal loudness contour. Human ear perceive all frequencies equally loud at around 90 dB. How does that relate to visible contrast? It may mean that at around 2^(90/3)=1,073,741,824:1 native contrast we get a life-like image. My approach is far from scientific but nevertheless I wanted to share.

Discussion?
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Old 04-25-2015, 02:47 AM
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Very interesting thread! Thanks to this author! :-)

Is this widely accepted that:

"So here's a simple forumla for you to determine how contrast A measures against contrast B perceptionally:

log2(Contrast A)
________________
log2(Contrast B"

I thought that what was logarithmic was the sensibility of the eye to brightness level.

The eye can detect a very small change of brightness at low ADL level but you need major changes in brightness to perceive the difference between hight brightness level.

Last edited by Soulnight; 04-25-2015 at 02:54 AM.
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Old 05-12-2015, 11:29 AM
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Nobody? It is really sad that this thread should die away. It is one of the most interesting of the Avsforum! :-)
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Old 05-12-2015, 02:00 PM
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Quote:
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Is this widely accepted that:
No, it is not widely accepted, it was merely a speculation on my part. But I invite anyone to discuss.
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Old 11-02-2015, 08:55 AM
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I agree with Kris. Start a new thread, so this doesn't get lost here.

What screen did you use? I didn't see that anywhere in the article.

This might be a little more difficult to test, but it would be interesting to see how an ambient light rejecting screen measures in both rooms.

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Old 11-02-2015, 06:05 PM
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Great information again Anna@Flo.

I've found some of the tradeoffs between price and contrast ratio to be rather interesting. In the past I told some people that if the wanted to spend about $200k they could get 2000:1 on/off CR, if they wanted to spend about $30k they could get 5000:1 on/off CR, and if they wanted to spend about $3k they could get about 30k:1 on/off CR.

I think it would be somewhat interesting to see a graph of a very high ANSI CR DLP, like the Marantz 11S1 Seegs has up for sale here:

FS: Marantz VP-11S1 1080p Projector - High End Konica Minolta Optics

I can already predict how they would go to a large degree with the JVC being higher on the left side of the graph and the Minolta eventually taking the lead before getting to 50%. One reason I think it would be interesting though is that with the irises open for that projector the ANSI CR is probably as high or higher than most DCI 3 chip DLPs in theaters and the on/off CR is probably a little higher on the Marantz too. This is before some of the latest laser DLPs for digital cinema.

One theory I have is that projects like that Marantz can be perceived as having high ANSI CR in a bright room not because they actually have high ANSI CR in that kind of environment, but because they retain their sharpness down at the pixel level even in a white room, like alluded to in the article. Without actually doing any real math, the system ANSI CR results themselves are highly affected by room reflections, but when we go down to very fine detail even 10:1 contrast ratio between adjacent pixels can be a lot. Stick that in a white room where the room reduces that to 9:1 and it isn't really much different than in a dark room.

--Darin
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Old 11-02-2015, 07:27 PM
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Quote:
Originally Posted by darinp2 View Post
I think it would be somewhat interesting to see a graph of a very high ANSI CR DLP, like the Marantz 11S1 Seegs has up for sale here:
There used to be such a graph on the first page of this thread, but it looks like all Mark P's pictures have disappeared
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Old 11-02-2015, 09:43 PM
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I have never even thought about MTF and room effect. Now that would be an interesting test. Is there an easier way to measure MTF than with a dedicated instrument. I believe TSE mentioned a method in a thread years ago, but I haven't thought about it in ages.

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Old 11-10-2015, 12:27 AM
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Does anybody knows what the blacklevel value is for a professional dolby cinema? I think the peak brightness level is 31 footlambert.I would like to know the contrast ratio acheived in such a hitec cinema,anyone?
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Old 11-10-2015, 12:33 AM
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Does anybody knows what the blacklevel value is for a professional dolby cinema? I think the peak brightness level is 31 footlambert.I would like to know the contrast ratio acheived in such a hitec cinema,anyone?
At the Dallas theater it looked to me like the black floor was determined by the exit signs, or very close to it. I'm guessing 10s of thousands to 1 even then. I've heard that one of them actually turns the exit signs off. Wouldn't surprise me if they could get a million to 1 or more then, but not sure if that is in a document somewhere.

The best I've read for some of the laser projectors other than Dolby and other than direct lasers (don't think any of those are in theaters) is about 8k:1 for the projectors. I'm guessing laser IMAX is somewhere around there.

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Old 11-10-2015, 12:40 AM
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Thanks for you reply,so i guess a JVC would do with its measured 150000:1 contrast ratio In my home cinema?
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