Some people are still being told that 200:1 is all we can see.... - Page 4 - AVS Forum
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post #91 of 505 Old 12-28-2006, 04:03 PM
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Quote:
Originally Posted by darinp2 View Post

Just to be clear, is your position that a display would only need to be able to display 300:1 for any one frame for us to not be able to see improvements to the CR at one time from that system, or not?

By "per picture element" are you talking about per pixel, or per full picture? If your position is that each full screen image only needs 300:1 for us to not be able to see improvements beyond that, then why not answer the question about MrWigggles example image?

I think most of us agree that the system needs a huge dynamic range in order for us to not see improvements in on/off CR, but as far as CR in individual images, is your claim 300:1 as the limit?

--Darin

Now you are cross examining me about my speculation about a mythical display which delivers 300:1 per pixel CR. I will further speculate that the the ANSI CR (4x4) of such a 1080p device would be >>10,000:1!!

Frankly I do not know what the MrWiggles example image is, nor do I care at this point.

You have asked for references and I have given you a Heinrich and Bach paper. That paper contains references to other publications that you can track to your heart's content. If you dissagree with their introductory statement

"Whereas the usable light intensity in our visual world varies by approximately eight orders of magnitude, the range over which we discriminate differences in light intensity varies only approximately 100-fold. Photochemical and neural mechanisms keep the limited range of discriminability in the range of the prevailing luminance, known as luminance adaptation", take it up with them and other noted HVS researchers!

I am puzzled by your continued personal attacks on my "understanding" of the limits of the HVS, despite the fact that I have stated that one should not use the HVS CR numbers to draw any conclusions about display device instantaneous CR benchmark numbers (ANSI CR in particular).
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post #92 of 505 Old 12-28-2006, 05:04 PM
 
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Quote:
Originally Posted by HoustonHoyaFan View Post

Now you are cross examining me about my speculation about a mythical display which delivers 300:1 per pixel CR. I will further speculate that the the ANSI CR (4x4) of such a 1080p device would be >>10,000:1!!

Frankly I do not know what the MrWiggles example image is, nor do I care at this point.

You have asked for references and I have given you a Heinrich and Bach paper. That paper contains references to other publications that you can track to your heart's content. If you dissagree with their introductory statement

"Whereas the usable light intensity in our visual world varies by approximately eight orders of magnitude, the range over which we discriminate differences in light intensity varies only approximately 100-fold. Photochemical and neural mechanisms keep the limited range of discriminability in the range of the prevailing luminance, known as luminance adaptation", take it up with them and other noted HVS researchers!

I am puzzled by your continued personal attacks on my "understanding" of the limits of the HVS, despite the fact that I have stated that one should not use the HVS CR numbers to draw any conclusions about display device instantaneous CR benchmark numbers (ANSI CR in particular).

You're puzzled? You're being extremely confusing. Darin and I and others have been fairly clear about what different numbers mean. I specifically cited a number of just 150:1 as a limitation right *at* a high contrast boundary, which would be very much akin to what you seem to be indicating as "per-pixel" contrast. Yet you have made a number of ambiguous posts apparently in disagreement with Darin and myself and others and what seems to be in agreement and support for the claims upon which this thread was based: namely that humans can only see a couple or a few hundred to one across a scene at one any instant in time (i.e. at larger angles, rather than the extremely small angles at a boundary which I agree impose severe limits in CR capabilities of seeing) thus claiming that projector contrast capabilities (namely ANSI CR) need not be higher than these tiny numbers because according to the logic we cannot see more than this across a scene.

So you've written a number of very ambiguous and contradictory posts which are confusing and are difficult to be interpreted any other way than in support of the originaly claim, and then you want to say that that's not what you're saying. And then you act surprised and puzzled when Darin tries to pin you to what exactly you're trying to say, especially given the evasive nature of your posts thus far and your refusal here and previously to do any simple tests or apply some common sense to the question.
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post #93 of 505 Old 12-28-2006, 05:10 PM
 
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Quote:
Originally Posted by Raul GS View Post

However, all of this argument can be said to be "much I do about nothing", since the argument that contends a 200:1 static, and dynamic range exceeding the 100s of thousands easily suggests that today's projectors do not come close to approaching the limits of visual acuity of your avg human. That is, the dynamic range model recognizes that both the ANSI and On/Off CR currently available through both CRTs and digital projectors are still not within the boundaries of the limits of human perception, so there is no need to argue for a conspiracy that is trying to limit the progress/development of better technology.

The first post in the thread expressly stated the contention: that ANSI CR or projector CR beyond a couple hundred to one is not necessary because we cannot see more than a couple hundred to one in a single scene. However you intepret that in terms of the eyes ability to adapt or restrictions there really is irrelevant. The explicit claim that I hear many make is that humans can only see 100:1, or 200:1 or 300:1 or whatever number you want, "at any one time." This claim naturally leads one to believe that simultaneous contrast ratios in displays that exceed this number are unnecessary. Many anecdotes illustrate that indeed people are being told this and ANSI CR capabilities and CR capabilities of displays are being poo-pooed as irrelevant because we can't see that much anyway.

This thread was created in direct and unambiguous response to these claims, which are completely errant claims. It is not some kind of concerted effort on anyone's part to "invent" a conspiracy about limiting projector progress. Instead, it is in direct response to the errant claims being made by some about what humans can see, often based on severe misinterpretations. If these claims were not being made, and it was accepted and understood that indeed we can see very significant contrast ranges in a single scene that far exceed what current displays are capable of producing, then there would be no need for this thread at all and your accusation might have merit. But that clearly is not the case.
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post #94 of 505 Old 12-28-2006, 05:15 PM - Thread Starter
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Quote:
Originally Posted by gremmy View Post

Since on/off contrast of this magnitude is easily measureable with the right equipment, I certainly hope that no ISF technician was laughing this off as an unattainable goal. If it was just an attendee, then we can chalk it up to ignorance. But a tech? That person should know better.

It was an attendee, and the other occasion in 2005 which appeared to confuse ANSI as the most CR we can see (200:1) was also an attendee, but both said that the person knew what they were talking about so believed them and dismissed anything to the contrary.

Iif the course is giving the wrong impression then something needs to be changed. If it's being taught that way, then that's a further worry.

Another thing that was mentioned was that ISF greyscale calibration was a waste of time with a room that had bright coloured walls and was not a batcave. Whilst I can see the relevance of that - a bright blue object could end up cause a blue wash bouncing back from the walls onto the screen, you will still notice red skin tones or pink whites if the greyscale is wrong, so although the room isn't perfect, there's no reason why you shouldn't correct errors elsewhere IMHO. I don't know if that was a conclusion of the attendee or if it was actually said that way, but if so that would put an awful lot of ISF calibrators out of business and would be a shot in the foot for the ISF itself, so I can't imagine them actually saying that.

Gary

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Originally Posted by elmalloc
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post #95 of 505 Old 12-28-2006, 05:36 PM
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Quote:
Originally Posted by tbrunet View Post

I removed my own post. Is it possible you have issues with empirical data?

No, I have a problem with someone who trolls any thread related to contrast ratio and then whose sole contribution to such threads is to post links to things, generally offering very little in the way of evaluation or analysis of your own -- all of this in an attempt to challenge people without getting your own feet wet in the logic of the debate.

I've read several of these threads where Darin and Chris get tangled up in these troll fests with you. These threads generally follow this script:

1) Darin makes a good point with real analysis and explanation
2) Chris makes a good point with real analysis and explanation
3) You post a link with no real analysis of your own, often misinterpreting and misapplying data.
4) Repeat... for pages and pages and pages

I'm beginning to think that you cannot think for yourself. If the mods removed your ability to post links, I'm not sure you'd have anything to say.

Oh, and just in case you plan on responding to this by posting a link, please allow me to beat you to the punch:

http://secure.hop.com/index.cfm?AFID=10&redirCampID=27


P.S.

Mods, if this is over the line, just know that I won't be responding in this thread anymore, so hopefully I can get a pass here?
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post #96 of 505 Old 12-28-2006, 06:22 PM
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Quote:
Originally Posted by HoustonHoyaFan View Post

You have asked for references and I have given you a Heinrich and Bach paper.

You have claimed that your chief scientist says 300:1 is the limit and that there is 50 years of research to back this up, yet the only link you provided says 100:1. So, with 50 years of research, which is it. 100:1 or 300:1?
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Originally Posted by HoustonHoyaFan View Post

I am puzzled by your continued personal attacks on my "understanding" of the limits of the HVS, despite the fact that I have stated that one should not use the HVS CR numbers to draw any conclusions about display device instantaneous CR benchmark numbers (ANSI CR in particular).

I usually respect what you say, but right now you are doing a pretty good imitation of tbrunet claiming that CR beyond 219:1 is not possible with our 8 bit video, then looking for any link he can find that implies linearity while refusing to tell us what the correct ft-lamberts levels are for things like 25%stim (or 25 IRE) with 10 ft-lamberts for 100 IRE and also refusing to even admit that he doesn't know. And refusing to do any measurements of light levels to support his claims. All that while claiming to understand this subject better than some of the rest of the people here (like Guy Kuo and Greg Rogers).

Over the last couple of years when the subject of how much instantaneous CR projectors need before we cannot detect improvements comes up you often post that 300:1 number you posted here. If it isn't relevant, then why have you brought it up multiple times? If it is relevant, why don't you tell us how you think it is relevant? It doesn't even match the number in the one link you gave.

You claim:
Quote:
Originally Posted by HoustonHoyaFan View Post

It is more a measure of the range of light levels that the HVS can discern in a single visual frame. levels outside that range are clipped into white and crushed into black.

So, shouldn't we observe things outside that range getting clipped in our vision if we do a test? For instance, if we have transitions that are 20:1 above a reference level and 20:1 below that reference level, one of those better get clipped or there is at least a 400:1 range that a person is seeing the transitions for without clipping. Do you disagree?

You've been making this 300:1 claim long enough and in a smart alec way claim that you understand it, so I don't understand your apparent refusal to explain what you think it means. And with 50 years of research you should be able to point us to something that matches the 300:1 claim you and your chief scientist support instead of one that is off by about 3x from that. Why not say 100:1 if you think that is the limit?

--Darin

This is the AV Science Forum. Please don't be gullible and please do remember the saying, "Fool me once, shame on you. Fool me twice, shame on me."
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post #97 of 505 Old 12-28-2006, 06:23 PM
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Originally Posted by ChrisWiggles View Post

You're puzzled? You're being extremely confusing. Darin and I and others have been fairly clear about what different numbers mean.

Just wanted to make sure this is personal.

It is pretty clear you know absolutely nothing about the HVS. I am not sure why you are attempting to have a conversation on the subject. Whatever naive tests you come up with, the HVS will still have <300:1 CR on a per frame basis.

The wierd thing is that my first post on this thread was to Tom cautioning him about confusing the HVS CR number with ANSI CR number.
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Originally Posted by HoustonHoyaFan View Post

Note that the < 300:1 is not the same as an ANSI CR measurement. It is more a measure of the range of light levels that the HVS can discern in a single visual frame. levels outside that range are clipped into white and crushed into black.

In fact, you dug up an old post of mine and included it:
Quote:
Originally Posted by HoustonHoyaFan View Post

People may not like it, but most medical research supports the conclusion that the simultaneous contrast range for the HVS is < 200:1! To put that number in perspective, the typical contrast range for a glossy magazine/book cover is only 60:1!

The problem occurs when people then try to use those numbers to say one only needs 200:1 on/off or even 200:1 ANSI CR, which is clearly incorrect.

At the time I thought that was odd, now I understand.

I see from your numerous "Darin and I" that you are Darin's lapdog, and you are trying to pick a fight to impress him. Well where I come from we don't play that hide behind a computer game. You want to call me out, pick a time and place and I will come to you. If you are man enough, do it to my face, and we will take it from there.
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post #98 of 505 Old 12-28-2006, 06:29 PM
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Originally Posted by dlarsen View Post

Some interesting optical illusions that seem to demonstrate the phenomenon.

http://www.hutchinsoncenter.umaine.e...ve/DynLum.html

I like those. They show multiple things. One, how the proximity of bright to dark affects things at different points in our vision. People should be able to see from that that a person trying to measure the most CR that anybody could detect before they couldn't detect any improvements could fix somebody at a viewing ratio that would not give the maximum, but some more limited value. Also, they could use smooth transitions (like smooth sine waves) instead of sharp transitions and likely get a lower value than the maximum. Of course, finding the maximum under all conditions is about doing the things that give the maximum, not things that give a lower value because of some other limitations.

--Darin

This is the AV Science Forum. Please don't be gullible and please do remember the saying, "Fool me once, shame on you. Fool me twice, shame on me."
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post #99 of 505 Old 12-28-2006, 06:40 PM
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Originally Posted by darinp2 View Post

Over the last couple of years when the subject of how much instantaneous CR projectors need before we cannot detect improvements comes up you often post that 300:1 number you posted here.

Not true. In fact, as in my post your lap dog came up with, I have consistently maintained that one should not confuse the HVS CR number with an ANSI CR number.
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post #100 of 505 Old 12-28-2006, 06:42 PM
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Originally Posted by HoustonHoyaFan View Post

Well where I come from we don't play that hide behind a computer game. You want to call me out, pick a time and place and I will come to you. If you are man enough, do it to my face, and we will take it from there.

My daddy can beat up your daddy. Meet me behind the lunchroom at recess....

Edit: If you think that part of your post is silly enough that you want to edit it out, I'll delete this post...
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post #101 of 505 Old 12-28-2006, 06:43 PM - Thread Starter
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But isn't it being confused with an on/off number which is equally misleading?

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Originally Posted by elmalloc
Who says Cameron is "right" and why do we care about him so much - lol!

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post #102 of 505 Old 12-28-2006, 06:53 PM
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Originally Posted by HoustonHoyaFan View Post

Not true. In fact, as in my post your lap dog came up with, I have consistently maintained that one should not confuse the HVS CR number with an ANSI CR number.

Of course it shouldn't be confused with ANSI CR. I have explained how ANSI CR shouldn't be confused with simultanteous CR or instantaneous CR, so your statement that it shouldn't be confused with ANSI CR doesn't tell us what you think the implications are. Why not just tell us? And if the number is 300:1 with over 50 years of research supporting that, you should be able to provide links to research that says 300:1, not 100:1. I see that you still don't seem to want to tell us which number is the right one. The 300:1 number is a lot closer to the results from the Contrast Sensitivity research over the years that has been discussed, especially why it isn't even about determining the upper limit.

Why not just tell us what you think the implications of the 300:1 instantaneous limit you claim are? Telling us that it shouldn't be confused with the ANSI CR number doesn't tell us anything knowledgable people didn't already know and doesn't answer the question.

It sure seems like you are trying to avoid giving straight answers to things like, "And you should be able to tell us whether your position is that people would not be able to perceive improvements beyond 300:1 simultaneous CR in any image or not." and are trying to blame us for asking. Why not just make your position about that clear? Including if you think it has nothing to do with whether we could perceive improvements beyond 300:1 simultaneous CR or not.

--Darin

This is the AV Science Forum. Please don't be gullible and please do remember the saying, "Fool me once, shame on you. Fool me twice, shame on me."
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post #103 of 505 Old 12-28-2006, 07:04 PM
 
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Originally Posted by HoustonHoyaFan View Post

Just wanted to make sure this is personal.

It is pretty clear you know absolutely nothing about the HVS. I am not sure why you are attempting to have a conversation on the subject. Whatever naive tests you come up with, the HVS will still have <300:1 CR on a per frame basis.

I have not personally attacked you. I did express some disbelief in your positions and the nature of your postings in this thread, which have been confusing, contradictory, and ambiguous.

Darin asked you for clarification of what your 300:1 number meant and applied to. You can think I'm an idiot and don't know anything. I don't care. But at the very least clarify what your position is. It is very much unclear where you stand and what you are trying to say. You make statements which seem to defend claims that humans can only see 300:1 across a scene, and then say that this has nothing to do with ANSI CR. An Ansi CR checkeboard is "a scene" and so to maintain logical coherence I have to interpret this to mean that you are making very much contradictory and hypocritical statements. Fine. Insult me for being too dense and unintelligent to properly interpret your posts. That doesn't bother me. But please clarify my understanding of your position if I am mischaracterizing it.

But you have not done that at all yet. Instead you refuse to do simple tests, you refuse to clarify your statements, and you basically refuse to engage in the discussion in any substantial way. Instead you accuse me of not knowing anything about the HVS and being Darin's lapdog. Why don't you put that energy into articulating your point?

Quote:


I see from your numerous "Darin and I" that you are Darin's lapdog, and you are trying to pick a fight to impress him. Well where I come from we don't play that hide behind a computer game. You want to call me out, pick a time and place and I will come to you. If you are man enough, do it to my face, and we will take it from there.

Now I'm being challenged to a fist-fight? All I did was express dismay and frustration at your confusing and ambiguous posts which seemed to posit totally contradictory views. By all means just clarify what the heck you mean, because you've thrown so many contradictory arguments out there I don't know what your position is. Do you agree, or disagree with what I've been saying? Lets just start with that, and then maybe we can go from there.
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post #104 of 505 Old 12-28-2006, 07:14 PM
 
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So here, let me simplify my understanding of your position Houston:

1) We cannot see more than 300:1 CR in a single scene.
2) We can see much greater than 300:1 with an ANSI checkerboard

So, how is an ANSI checkerboard not "a single scene?" Please explain how these two things which on their face are clearly in disagreement, can be true at the same time. Or conversely, please correct my understanding of what you are trying to say. But whatever you choose to do, please articulate what the f**k you mean because I'm pretty irritated going around in circles with people who are not willing to make concrete statements about what they think is true.

For instance, here is my position based on figures which I have some trust in:

1) We can see about 5 orders of magnitude in a single scene, or 100,000:1
2) This means that ANSI CR contrast performance that is significantly less than that cited in #1 is above our visibility threshold and does not exceed the capabilities of our vision, generally.

From these two points of view which I hold (accurately or not), I can say that ANSI CR performance of say 500:1 does not exceed our visual capability and there is room for improvement which could be detected by human viewers viewing that scene at a relatively normal viewing ratio that we encounter in most home-theater viewing environments.

Please explain your position in this type of manner, in a way that is on-topic and addresses the various display-related issues that are being discussed.
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post #105 of 505 Old 12-28-2006, 07:53 PM
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Originally Posted by skogan View Post

My daddy can beat up your daddy. Meet me behind the lunchroom at recess....

Edit: If you think that part of your post is silly enough that you want to edit it out, I'll delete this post...

My dad has been dead for > 10 years, so your dad may last a few rounds.
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post #106 of 505 Old 12-29-2006, 12:43 AM
 
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You're not going to articulate your position? Or explain what the 300:1 number means?
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post #107 of 505 Old 12-29-2006, 03:16 AM
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I recall having a discussion like this one a year or so ago with Rogo, perhaps Darin, others. The solution as I recall was that the 300:1 max CR is correct, but only for a patterned type test, say a checkerboard or bright-dark lines with a high spatial frequency (i.e. small angular separation).

Real scenes are not like this, there are large areas of bright and dark, with their own edges. The idea is that transitions beyond 300:1 cannot be differentiated from those at 300:1. But, since the transitions could be say 15fL/0.05fL in one spot but say 3fL/0.01fL in another spot, we need the CR of 15fL/0.01fL or 1500:1 to not produce a hazy scene.

I have 800:1 LCD panels, recently had a 1300:1 panel, it was very obvious that I was perceiving a much higher CR with the latter. The meaning of the 300:1 is that in a 15fL/0.05fL transition one could not differentiate between that and a 15fL/0.0fL transition. Now Chris might argue against this with his felt test, but that does introduce a new edge, and you see that edge. I would maintain that yes, you do see the edge, because you are able to perceive a transition between say 0.05fL/0.01fL, as that is only 5. Now if he argues that covering a square completely with felt makes that square look blacker than another square, that would be a problem.

So my take is that both sides could be correct. We see many edges at once with our wide field vision, and all of this information goes into the CR perception. As a previous poster said, we need 300:1 at all transitions and all intensity levels to max out.
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post #108 of 505 Old 12-29-2006, 06:18 AM
 
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Quote:
Originally Posted by ChrisWiggles View Post

Again, if you could only see 100:1, 200:1 or even 300:1, you would have very significant visual impairments and at the very least you shouldn't ever be driving a vehicle at night because it would be nearly impossible for you to see anything. Yet that's what is being claimed, unfortunately, by people who should be able to explore this with relative ease and easily "see" that this claim is quite silly.

Local Contrast Perception
"While we can see a vast dynamic range across a scene, we are unable to see more than a small portion of it within a small angle subtended by the eye. This inherent limitation can be explained by scattering properties of the cornea, lens, and vitreous fluid, and by interreflection from the retina. It reduces the visibility of low contrast features in the neighborhood of bright light sources. One example is the difficulty encountered when trying to discern the license plate numbers of an oncoming car at night if the headlights are on."
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post #109 of 505 Old 12-29-2006, 06:28 AM
 
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Originally Posted by gremmy View Post

3) You post a link with no real analysis of your own, often misinterpreting and misapplying data.

OK gremmy, I'll analyze the "facts" for you..above I linked/quoted for you a master thesis on the very subject matter of 'dynamic range', or in this case HDR. Tell me if/where I misinterpreted any info from Matthew Trentacoste research?
http://www.cs.ubc.ca/~mmt/Papers/MscThesis.pdf
Please point out all the mathematical errors he has made, oh and BTW, he also goes into extreme detail on the SM coding of LDR images, JND, HVS, perceptual models, CIE color models, and target intensity. According to his research Chris, Darin, ect. do not have a clue regarding the coding of image INTENSITY.
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Originally Posted by tstites View Post

Chris,

You have it exactly backwards...

Whats new
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post #110 of 505 Old 12-29-2006, 08:17 AM
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Quote:
Originally Posted by Raul GS View Post

Within what time line?


As I said within my post: "This is all within the same field of view at the same time."

-Steve
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post #111 of 505 Old 12-29-2006, 08:26 AM
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Originally Posted by HoustonHoyaFan View Post

Just wanted to make sure this is personal.


I see from your numerous "Darin and I" that you are Darin's lapdog, and you are trying to pick a fight to impress him. Well where I come from we don't play that hide behind a computer game. You want to call me out, pick a time and place and I will come to you. If you are man enough, do it to my face, and we will take it from there.

Dude. Making threats in an interweb forum:

1) Is Lame

2) Is the epitome of hiding behind your computer screen.

Unless you are serious with intent, in which case let the filing of charges begin!

-Steve
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post #112 of 505 Old 12-29-2006, 10:11 AM
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I have noticed some interesting consistencies in the devolution of thread discussions, this one in particular being a case in point:

1. The topic is CR.
2. Chris and Darin will always participate.
3. They will invariably piss people off.
4. The debate turns ad hominem
5. Little is actually learned.
6. New participants are totally turned off.


"A foolish consistency is the hobgoblin of little minds"
-Ralph Waldo Emerson
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post #113 of 505 Old 12-29-2006, 10:48 AM
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Quote:
Originally Posted by scaesare View Post

Dude. Making threats in an interweb forum:

1) Is Lame

2) Is the epitome of hiding behind your computer screen.

Unless you are serious with intent, in which case let the filing of charges begin!

Where exactly is the threat?
I am very serious with intent!
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post #114 of 505 Old 12-29-2006, 11:21 AM
 
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Originally Posted by HoustonHoyaFan View Post

Where exactly is the threat?
I am very serious with intent!

So, are you going to answer the questions that have been posed to you or not?

I am just trying to understand your position.
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post #115 of 505 Old 12-29-2006, 11:40 AM
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Quote:
Originally Posted by mdtiberi View Post

I have noticed some interesting consistencies in the devolution of thread discussions, this one in particular being a case in point:

1. The topic is CR.
2. Chris and Darin will always participate.
3. They will invariably piss people off.
4. The debate turns ad hominem
5. Little is actually learned.
6. New participants are totally turned off.


"A foolish consistency is the hobgoblin of little minds"
-Ralph Waldo Emerson

Good summary.
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post #116 of 505 Old 12-29-2006, 11:47 AM
 
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Originally Posted by tbrunet View Post

OK gremmy, I'll analyze the "facts" for you..above I linked/quoted for you a master thesis on the very subject matter of 'dynamic range', or in this case HDR. Tell me if/where I misinterpreted any info from Matthew Trentacoste research?
http://www.cs.ubc.ca/~mmt/Papers/MscThesis.pdf
Please point out all the mathematical errors he has made, oh and BTW, he also goes into extreme detail on the SM coding of LDR images, JND, HVS, perceptual models, CIE color models, and target intensity. According to his research Chris, Darin, ect. do not have a clue regarding the coding of image INTENSITY.
Whats new

I am making an exception to my policy of not responding to this user's posts, but it is interesting to point out that the paper he cites quite clearly bolsters the claims that I have made in this thread, and those that Darin have made. Despite the claims here to the contrary that I don't have a clue, it's fairly clear to anyone who actually read through the excerpts 'tbrunet' is citing and the paper he is referring to, that it is very much in agreement with my claims here. That should be of no surprise since it is a paper from one of the Brightside guys, and they are one of the primary sources I have been citing thus far.

Here is the entire section, unaltered, lest there be any ambiguity about what is being discussed in the excerpts 'tbrunet' is citing, which quite clearly are in agreement with what I have been putting forward in this thread:

Quote:


2.1.1 Local Contrast Perception
While we can see a vast dynamic range across a scene, we are unable to see more than a small portion of it within a small angle subtended by the eye. This inherent limitation can be explained by scattering properties of the cornea, lens, and vitreous fluid, and by interreflection from the retina. It reduces the visibility of low contrast features in the neighborhood of bright light sources. One example is the difficulty encountered when trying to discern the license plate numbers of an oncoming car at night if the headlights are on. Typical LDR display settings cannot produce the contrast ranges for this to have an effect on the perception of the displayed image. However, it has significant influence on perception of real world scenes, and of images on HDR displays.

Ocular scattering, a well documented phenomenon, depends on a large number of parameters including spatial frequency, wavelength, pupil size as a function of adaptation luminance [51], and age of the subject. This scattering of light has been the topic of numerous studies and is conventionally modeled as an Optical Transfer Function (OTF) in the angular frequency domain and as a Point Spread Function (PSF) in the angular domain. Different researchers [55, 56] have derived models based on various sets of the aforementioned parameters and Vos [75] attempted to unify a number of the existing models. Much of the subsequent work [17, 48] has either validated or built upon his model, largely by considering additional parameters of the model or by optimizing for specific applications.

While different values are reported for the threshold past which we cannot make out high contrast boundaries, most agree that the maximum perceivable contrast is somewhere around 150 : 1. Scene contrast boundaries above this threshold appear blurry and indistinct, and the eye is unable to judge the relative magnitudes of the adjacent regions. From Moon & Spencer's original work on glare [52], we know that any high contrast boundary will scatter at least 4% of its energy on the retina to the darker side of the boundary, obscuring the visibility of the edge and details within a few degrees of it. If the contrast of an edge is 25 : 1, then details on the darker side will be competing with an equal amount of light scattered from the brighter side, reducing visible contrast by a factor of 2 in the darker region. When the edge contrast reaches a value of 150 : 1, the visible contrast on the dark side is reduced by a factor of 12, rendering details indistinct or invisible. Figure 2.1 shows the model by Deeley et al [17] at several adaptation luminances.

Just because human observers cannot perceive all details in the presence of high
contrast features, one cannot claim high contrast content has no effect - clearly it does. An observer will notice when one region is much brighter than another, both by the challenge it creates in viewing the boundary, and by the accommodation that goes on when shifting from side to side. When the threshold is very large, observers notice a sensation and may even experience discomfort as they attempt to see detail near a bright source. A familiar example for any driver is that a photographic print of a nighttime scene with an oncoming car and headlights is merely an allusion to the real experience - it cannot duplicate the visceral experience of glare, or reproduce the effect it has on a human observer. It is exactly this kind of experience that an HDR display can uniquely reproduce.

HDR display technology described is Section 2.3 only exploits the inability of humans to see detail in the immediate vicinity of a highcontrast boundary; it makes no assumptions about our overall response to varying brightnesses. Relative (and even absolute) luminances are maintained, and edges will be reproduced exactly when they are below the maximum contrast of the front display of about 250 : 1 in the current production model. Only when this range is exceeded is some fidelity lost near high contrast boundaries, but this effect is well below the detectable threshold, and has not been visible in any experiments [65].

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post #117 of 505 Old 12-29-2006, 12:03 PM
 
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Quote:
Originally Posted by ChrisWiggles View Post

Here is the entire section, unaltered, lest there be any ambiguity about what is being discussed in the excerpts 'tbrunet' is citing, which quite clearly are in agreement with what I have been putting forward

Well now it seems you admit 'Matthew Trentacoste' knows a thing or two regarding HDR..now lets see what else you are clearly in agreement with?

"This fact is incorporated into the design of all optioelectric transfer functions (OETFs), such as the television standard Rec. 709 and the computer standard sRGB , which are similar to L* described in Section 2.1.2.

The response is plotted in Figure 2.3. A linear segment is included for practical reasons and the break occurs where the function equals an L* value of 8, corresponding to a contrast ratio of 100:1. Obtaining values below 8 is rare in practice and the break is considered the effective limit for video applications, reinforcing the fact that L* is only applicable to LDR images.

We were unable to ascertain the exact method that inspired the formulation of L* and have been forced to make an educated guess based on targeted applications and indirect evidence. Regardless of the exact function, it is apparent that it is not an accurate fit for larger dynamic ranges."

Have a nice day
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post #118 of 505 Old 12-29-2006, 12:10 PM
 
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Well now it seems you admit 'Matthew Trentacoste' knows a thing or two regarding HDR..now lets see what else you are clearly in agreement with?

STOP MISREPRESENTING MY OPINIONS.
This statement insinuates that at some time in the past that I had disagreed with this person and his papers. I have never said anything like that, ever!

I have asked you many times previously to refrain from mis-representing my positions and statements. It is clearly intentional on your part, because you continue to mis-quote me and put words and opinions in my mouth which I never even came CLOSE to saying. It is unbelievably disingenuous for you to continue to insinuate this nonsense about my statements. Stop it.
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post #119 of 505 Old 12-29-2006, 12:19 PM
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Quote:
Originally Posted by ChrisWiggles View Post

So, are you going to answer the questions that have been posed to you or not?

I have answered "the questons" several times now.

1) The HVS can discriminate differences in light intensity of < 200:1 (99.999 % pop),at any given instance in time. That window varies over a dynamic range of > 10^8, and can change in as little as < 100 ms.

2) I do not know what per frame display instantaneous CR would exceed the limits of 1) above. I suspect that the Sony LCD which has measured ~1,300:1 ANSI CR still does not exceed the HVS limits.
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post #120 of 505 Old 12-29-2006, 12:32 PM
 
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Quote:
Originally Posted by ChrisWiggles View Post

This statement insinuates that at some time in the past that I had disagreed with this person and his papers. I have never said anything like that, ever

Fair enough, I take it every time you and Darin insisted the the 100:1 number used by 'Matthew Trentacoste' or myself was "wrong", and actually should read infinity or 1000:1 ....never happened? That I was correct all along, and now you see the light!(pun intended). Amazing
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