Originally Posted by Drexler
The whole discussion feels a bit like one guy argues with complex fluid dynamics and aerial mechanics calculations with references to scientific papers that it is impossible for the bumblebee to fly, whereas his friend repeatedly responds "but look!!!, I can see it hover right in front of me!!!"
That is a reasonable analogy. Another one I think is that this is somewhat like a person claiming that people can't lift more than 20 lbs of bricks at one time and continues to give their own interpretation of what the science says on the subject matter, but won't actually go do a test to see if they or others can ever lift more than 20 lbs of bricks at once.
The human visual system is more complicated than the lifting example, but it doesn't mean that intelligent people can't test a hypothesis that humans cannot see across a range of more than 1000:1 in any single images when looking around different locations with them. This doesn't require an ophthmalogist or even a scientist, but does require some intelligent thought not to make some mistakes that seem common.
If a person measures the levels for an image setup and people can see highlight detail and lowlight detail by looking around, then by definition the relevant white level for their vision must have been at least as high as one step down from the brightest detail they could differentiate and the relevant black level for their vision must have been at least as low as one step up from the darkest detail they could differentiate. If the ratios for those one steps in were more than 1000:1 and people are able to differentiate those levels from one step out, then by definition those people have seen detail that was separated by more than 1000:1 in that image.
Originally Posted by Trepidati0n
Note: Your hand-puppet example is a red-herring argument. Stare into a flashlight for a minute then do your hand puppet. How long does it take for you to see the "shadow"? By your example it should be instant. Care to wager i'm wrong?
You aren't wrong about the expected result of your test, but I would say you are wrong about how it applies to Drexler's claim. Do you have any idea how much CR range you are talking about for your example? Others have made these arguments years ago and so I have tested and measured some of these things. Your flashlight example can be millions:1. I don't remember the exact numbers I measured for this kind of test, but I'm sure I posted them years ago and they were not very relevant to limits of 100:1 or 1000:1.
I'm guessing you wouldn't use a test of whether somebody could pick up a car to prove that they couldn't pick up 20 lbs. You are right that the disagreement here is about what the levels are, not whether there are limits to human vision in short amounts of time that are much smaller than those when given large amounts of time. I think we all agree on that. The ballpark for the actual limits for single images are relevant to what we experience with projectors and the 1000:1 claim for single images is wrong.
Originally Posted by Trepidati0n
I've read this whole thread. What makes you qualified?
That is a fair question. You don't have to believe me though. Do a proper test yourself and you should be able to find out whether coderguy's claim about people not being able to see across more than 1000:1 in any single images is true. I will also stand on my record that when I describe tests people have been able to reproduce them themselves and get reasonably similar results.
As I said, people in the past on this very forum have made similar claims about how limited human vision was for single images and some of us have actually done tests. People also made claims about how higher on/off CR (like more than 4000:1) would be impossible to see any difference with to human vision and so I did tests to help show that this was not the case. I think time has been on my side on that one as projectors have improved on/off CR and my positions have generally been validated.
I know I'm not the only person here intelligent enough to come up with reasonable tests of hypothesis like that, even when projectors had difficulty providing some of the ranges to make it easy to test. There are ways to create images that have bigger CR ranges than the projectors themselves can do (I'll describe one below). Now many people have projectors that can do some of the much larger ranges themselves without having to do too many special things to create images with high CR ranges.
For people in Seattle I have shown them some of this stuff in person so that they can see with their own eyes. I know I've had some advantages in having equipment to measure actual light levels fairly accurately, but others can do proper testing themselves with a little bit of help here.
Originally Posted by coderguy
You guys are not saying I'm wrong as much as you're really saying the Wiki is wrong and the scientist that explained it that apparently had a background in this stuff.
No, you are still wrong and blaming it on others.
Originally Posted by coderguy
Because I didn't come up with the number, I just said it seems to make sense.
You didn't come up with the number, but you are the one who is applying it to a situation that it doesn't apply to based on your own logic. Please don't blame the scientists because you applied something for an instant to all single images. Not the same thing with human vision.
Originally Posted by coderguy
That is why the displays need more contrast to do frame to frame stuff, but for intrascene our eye does have limitations in short periods of time.
Of course they do. They just aren't as low as you claim.
Originally Posted by coderguy
It got side-tracked, I came up with an experiment if someone wants to try it...
Try this, if any of you have old projector lamps or can just project very dark, set your display to like 2fL to 4 fL super super dim (if you can) and start watching stuff, what is the first thing you notice?
You start missing out all the detail, why is that?
The detail is still there, right?
It's because our eyes have trouble seeing the delineation in darker intrascene ranges, even when the delineation is there...
It is a good experiment for showing certain things (and something I have demonstrated for people and posted about here between a high gain screen and low gain screen), but it doesn't address the point of contention. I think you know that the issue of disagreement is your claim that people can't see across a range of more than 1000:1 from any single images (like a painting), even if they look around. As long as you are testing, why not test that actual thing? You have a JVC, so it shouldn't be that hard.
Here is one test people with projectors can try. I did tests like this years ago. Find a dark scene with a little bit of bright stuff. I can suggest things from more popular movies like The Dark Knight if it would help, but since it is already posted I will use some frames from The Last StarFighter. Consider the 4th and 5th images down at:
They contain a planet on a starfield. Either one could be used for this test. The discussion is an upper limit for the most range the eye can see from one image and easier images are therefore most appropriate. That would make the 4th one a good one, but I'll use the 5th one for now as I think it will work.
Whether you can get more than 1000:1 CR from the screen depends on the projector and screen. A recent JVC shouldn't have a problem with that itself and then it depends on the room, but there are other things that can be done to create more CR range from the image. For instance, go buy some black posterboard and put it up on the left side for this image and/or get some dark gray paper. Those things can be combined for an extra step of luminance.
For the 5th image I would suggest moving the projected image to the right to create some space between the left side of the projected image and the screen border. Maybe a foot or two. This will create an area of luminance even less than the projector can do itself for that scene.
If a projector has a feature to blank some of the image near the edge I would use some of it to make sure some of the image on the left part is as dark as the projector can go. For this test I would also turn the Brightness for the projector down a few notches to make sure it is attempting to do black for the darkest parts of the image.
The contrast control can be turned up to the point that detail in the planet starts to crush. Now a person can test themselves and then test on others to verify that what they believe they see is confirmed by what others see when those other people don't know what has been changed.
Relevant questions are things like can a person tell whether the detail in the planet is crushed or not (this will be controlled by settings in the projector) and whether they can see the step from the projected black, to the reflected black (the part on the screen on the left side between the image and the screen border), and the step from the reflected black to the screen border. If a person picked up some black posterboard or dark gray paper a relevant question is whether a viewer can tell whether it is up on the screen on the left side (I would place it so that the black from the projector is hitting the right half of this dark material).
As an example, if the brightest part of the planet is 40 cd/m2 and higher, the black on the left projected side is .02 cd/m2, the part of the screen the projector is not falling on is about .002 cd/m2 and the screen border is about .0002 cd/2m, then if the person can look and see the detail in the brightest part of the planed their relevant white level by definition is at least 40 cd/m2. If they can then look on the left side of the image and see the step between .002 cd/m2 and .02 cd/m2, then by definition their relevant black level is .02 cd/m2 or darker. In that case seeing this detail in one image would mean that they had seen detail that was separated by a ratio of 2000:1.
The black poster board or dark gray paper would of course create other levels. From memory of doing these kinds of tests myself the black poster board I got was less than .10 gain (maybe ~.05 gain). I could always verify at some point as the gain of the material can be gathered by measuring it with white light to get into an accurate range for a meter.
Pioneer and Panasonic have both demonstrated things related to this subject whether they meant to or not. I wasn't at CES when Pioneer showed a prototype plasma next to a current model, but the situation was described to me by somebody who was there and I saw similar things with a Panasonic (IICR) demonstration at CES 2012.
Pioneer had an image where there was bright stuff in the center of the screen (like a flower) and nothing surrounding it. On the current set the background 16:9 image was pretty clearly visible against the edge of the plasma, while on the prototype set the difference between the background and border was not visible. This was all while the detail in the center of the screen was visible to viewers who chose to look there. I was told that the current set did look like somebody who owned that year's Pioneer experienced at home, so didn't seem like they had made it look like bad black level on purpose. This was a set that could do pretty high intra-image CR for an image like that (definitely higher than 1000:1).
I saw a similar thing with the Panasonic demo and their current plasmas also did not have much trouble doing more than 1000:1 with images with bright stuff near the center of the screen.
I had the Planar 8150 and JVC (probably the RS20 or RS40) at the same time and did many side-by-side comparisons between them both by myself and with other people. I would block half of each image and flip the image for one side digitally so that both projectors showed the same content side-by-side on the same screen. With dark images like I described both projectors could do more than 1000:1 and my theater room is mostly black velvet (including the ceiling and floor).
My memory is that with both projectors setup to the same ft-lambers for white there were scenes where we could see that the Planar was crushing detail near white, while the JVC was not, and at the same time we could see that the JVC was doing darker black than the Planar.
There are multiple reasons that the implementation of the dynamic iris for the Planar would crush whites, but one of them is because normal people can see detail that is separated by more than 1000:1 in many single images (unless I and everybody I have tried things like this with somehow have super vision). Dynamic iris systems would be easier to implement without visible artifacts if people never could see detail that is across more than 1000:1 from single images.
There is a pretty good scene that I believe is in one of Woody Allen's movies where there is a girl sitting under a bright lamp in a dark study. The scene is mostly very dark, but there is detail near her that can be crushed or not. I know I've posted it on this forum before, but don't recall the thread.
I wonder if coderguy is going to claim that a person wouldn't be seeing detail across more than 1000:1 from what is in front of them if for example they could see the crushed whites on the Planar vs the JVC and the darker blacks from the JVC with a side-by-side of the following:
- Planar whites are at 42 cd/m2 with crushing there
- JVC whites are at 42 cd/m2 with visible detail between 40 cd/m2 and 42 cd/m2
- Planar black at about .02 cd/m2
- JVC black at about .004 cd/m2