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Digital Hi-End Projectors - $3,000+ USD MSRP

skogan's Avatar skogan
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Quote:
Originally Posted by armadillo View Post

So in the case of TV monitor, CR would not matter. If you sit in front of a projection screen, then it will matter, because your eyes can adapt to "subimages" of the larger picture.

I'm afraid I must disagree with this as well. Not the science, but your application of the science.

We are talking about the CR on the screen, not in your eye. What happens if in the top right corner there is a bright light, while in the middle of the screen it is dark. Your screen would crush the blacks in the middle of the screen because it is rendering the light in the corner. You would lose all definition in the center of the screen.

So even though the fovea may have the limit you suggest, that doesn't mean a small screen only needs 300:1 cr. Once again, I'm not disputing the 300:1 number, or the science behind it, I'm only disputing the way you are applying it.
armadillo's Avatar armadillo
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HHS: I missed that link before, but it neatly demonstrates the dynamics of contrast adaptation. Very cool.
armadillo's Avatar armadillo
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skogan: I don't know what you mean by saying that the "screen would crush the blacks". As I understand it, a monitor with CR of say 100:1 will display the bright light at 100x the dark area. The HVS would perceive that normally. If you had a monitor with 1000:1 and you would project the same image, it would have to make that light 1000x brighter than the black. The HVS would not be able to let you tell the difference in those exact relations. In fact, people have a hard time telling luminances apart. So if you didn't know what brightnes the light was in absolute terms, and you had two monitors with those CR, you would not be able to tell whether the higher CR monitor produced a light that 10x brighter than that of the other. I hope I have understood your point.
darinp2's Avatar darinp2
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Quote:
Originally Posted by armadillo View Post

skogan: I don't know what you mean by saying that the "screen would crush the blacks". As I understand it, a monitor with CR of say 100:1 will display the bright light at 100x the dark area. The HVS would perceive that normally. If you had a monitor with 1000:1 and you would project the same image, it would have to make that light 1000x brighter than the black.

The "black" could just be 10 times darker with the white the same. And if the "black" is near the far edge and the TV has a black frame, then one of the questions is whether you would be able to see the transition between the black frame and the "black" in the image that is more of a gray. If you can see that transition (because of low CR) then the TV had room for improvement in CR, because there is a CR at which the frame and the "black" in the image right next to it would be indistinguishable.

I still am not clear on your position about whether CR outside the few degrees of central vision matters. Are you fine with everything out there getting crushed so that you could not tell whether there was anything there or not? For example, if somebody was crouching in the shadows, you wouldn't be aware that they were there with low contrast ratio around them, while you would be with a higher contrast ratio around them (because of the Just-Noticeable-Difference factor). Do you only care about the foveal region of your vision? I think we can confidently say that a person who had no vision at all outside of a few central degrees of vision would be a danger to themselves and others. And their ancestors would have been eaten long ago if that is all the vision they had. High contrast ratios matter out there because they are one of the things that allows us to be aware of things out there. If you didn't want to be seen in the periphery of somebody's vision, you would want to wear something that was very similar to the background, because something that was high contrast with the background would make you easier to see.

--Darin
armadillo's Avatar armadillo
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darinp2: I was talking about relative values, not absolute black. We all would like to have absolute black. As to your point about peripheral vision, you are of course correct that it is important for our survival. Note, however, that our peripheral vision lacks color and responds primarily to motion contrast and not static contrast. This has to to with so-called lateral inhibition of interneurons in the retina. These in fact enhance contrast. But lateral vision is not really a relevant factor when watching movies. For example, when you watch a dialog with two people on the screen, you concentrate on the person speaking and you can see every little detail in their face. If you watched the same scene but forced yourself to concentrate on the features of the listener, you would not be able to tell any facial expression of the speaker, let alone hair color or details within the hair. So peripheral vision is important to change your foveal focus to something that may be just a silhouette or contrast change or movement, but you can't actually tell what it is unless you change your foveal area to that subject.
darinp2's Avatar darinp2
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Quote:
Originally Posted by HoustonHoyaFan View Post

The reason one cannot perceive the second image for a few seconds is that the adaptation mechanisms have moved the visual frame's dynamic range window. Literally, the frame's CR window is outside the range of the slightly grey disk so if is compressed into the background!

If that is true then shouldn't a black disk in place of the grey disk also be invisible with the same test?
Quote:
Originally Posted by HoustonHoyaFan View Post

If the CR was as large as 10^5 as has been suggested, no adaptation would have occured, ant the slight grey would not have vanished!

I don't think it shows that for multiple reasons. One, it doesn't say how small the CRs can be there for you to still see them. Do you think that illusion would have worked the same way if the disc had been black in the right hand image? Also, what I heard was "without the iris moving", not that there couldn't be any other factors like parts of the image moving to fall on different parts of the back of the eye. A single receptor in the eye could have a range of 100:1 without adaptation while all receptors in the eye put together could have a much higher range (since different receptors can be acclimated to different levels). Do you agree or disagree with that? It seems that one clue to me is that the person has to focus so that the white and then gray part fall on the same receptors in the eye. I doubt that having them fall on different receptors works.
Quote:
Originally Posted by HoustonHoyaFan View Post

At least that is my misunderstanding of the startup's researcher's explaination of the test.

I hope that you will get some more information from him and he will help explain the position.

It seems that your position in the example I gave about a dozen posts above in post #165 must be that a person couldn't see the things that are 400:1 simultaneously with the limit you believe is true for the full frame. But if that is a false assumption, please say so. That was the example with 4 levels at:

White laserpointer: Much higher than 20 ft-lamberts
White square: 20 ft-lamberts
"Black" from projector: 0.05 ft-lamberts
Posterboard: 0.0025 ft-lamberts

--Darin
darinp2's Avatar darinp2
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Quote:
Originally Posted by armadillo View Post

Note, however, that our peripheral vision lacks color and responds primarily to motion contrast and not static contrast.

Primarily yes, but that is different than saying it can't sense any static contrast.
Quote:
Originally Posted by armadillo View Post

But lateral vision is not really a relevant factor when watching movies.

Sure it is relevant to whether movies can even come close to what real life can do and whether things can seem real at all. I'm getting the feeling that you think that if we can't make out all the small details or what the exact contrast is out there then it doesn't matter, but that simply isn't the case. It isn't as good as our central vision, but CR is definitely relevant outside of the central few degrees.

--Darin
armadillo's Avatar armadillo
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What I'm saying is that the fovea can only do 300:1, peripheral vision pales in comparison. So if we had a display in which the center part is high contrast and the periphery has only 100:1, I would predict that your peripheral perception would be indistinguishable from that of display that had high contrast all around. You just cannot tell differences apart in your peripheral view. When I write this text, I cannot discriminate any icons on the right hand side of the monitor. Enhancing their contrast would not make a difference.
darinp2's Avatar darinp2
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Quote:
Originally Posted by armadillo View Post

What I'm saying is that the fovea can only do 300:1, peripheral vision pales in comparison. So if we had a display in which the center part is high contrast and the periphery has only 100:1, I would predict that your peripheral perception would be indistinguishable from that of display that had high contrast all around. You just cannot tell differences apart in your peripheral view. When I write this text, I cannot discriminate any icons on the right hand side of the monitor. Enhancing their contrast would not make a difference.

I tried your test and I could tell that there was a transition out in my periphery that was from bright to dark. If you can tell 300:1 in the very center and a difference between having 2:1 outside that on each side vs having 1000:1 outside that on each side, then the total that you were able to notice for the whole frame was higher than 300:1. Do you disagree? Also, it seems that you want to talk about the far periphery. How many degrees is the fovea again? And as I said, you don't have to be able to make out all the detail for a higher CR display to display the image in a way that the extra CR is noticable. All you have to be able to do is tell that there is a difference. Just to be clear, is your position that if you can tell a difference, but you can't make out all the detail, that the difference between what the displays were able to do wasn't visible?

And BTW. 300:1 and 100:1 in your example above is a lot more than 300:1 in the whole field unless you are saying the CR for the periphery is limited to within that 300:1 of the fovea.

--Darin
mark_1080p's Avatar mark_1080p
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Nonsense, Darin's example sheds light on this perfectly. IF you stare at a 300:1 transition, in your foveal vision, is the rest of the field of view (if all points outside of the foveal region are darker) crushed into black? Of course not. Therefore, we do see >300:1. Sure, if you stare at an extremely bright source, your eye becomes saturated with scattered light. But as Chris quotes from the paper, move the source outside the fovea, and you resolve detail in the shadows.

Further, we need not move our eyes to do it. Sure, lateral vision is less detailed, but we can see transitions in luminance. I read alot of scientific papers, not in this field, and I write them as well. You have to be careful in applying their conclusions to the real world. In my humble opinion, and I do make mistakes, you and HH are not applying the science properly.
armadillo's Avatar armadillo
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Darin: Check this link

http://www.cis.rit.edu/people/facult...p_9/ch9p1.html

at the bottom of the page, it'll give you the answer to your question.
ChrisWiggles's Avatar ChrisWiggles
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Quote:
Originally Posted by HoustonHoyaFan View Post

I see I was correct in my earlier post about your personal attacks on people who have a different opinion than yours.

That's a personal attack? It's an accusation of intellectual dishonesty, it's hardly an ad hominem attack. He is misquoting and misrepresenting sources. That's being intellectually dishonest. Your perception of what constitutes a "personal attack" seems somewhat strange to me.
ChrisWiggles's Avatar ChrisWiggles
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Quote:
Originally Posted by armadillo View Post

What I'm saying is that the fovea can only do 300:1, peripheral vision pales in comparison.

First of all, to be clear, this is YOUR claim. This is not the claim in the literature. It is also unclear what kinds of angles are involved.

Quote:


So if we had a display in which the center part is high contrast and the periphery has only 100:1, I would predict that your peripheral perception would be indistinguishable from that of display that had high contrast all around.

Ridiculous. Did you read the papers that you yourself linked earlier in the thread? In order to reproduce accurately real-world luminances far greater CR across a scene is necessary. We can sense and are affected by significant CR even where in localized regions we may lose the ability (for instance at a localized high-contrast boundary) to discern small changes in luminance adjacent to a bright image element. And of course, even pretending that the papers you earlier cited did not fully refute your thinking, what happens if a viewer decides to move their eyes around to view other parts of the image?

Quote:


You just cannot tell differences apart in your peripheral view. When I write this text, I cannot discriminate any icons on the right hand side of the monitor. Enhancing their contrast would not make a difference.

It certainly would make a difference if they were significantly brighter. You are typing on a computer monitor. Look at some text and turn on a bright light of flashlight next to the monitor pointed at your eyes. Can you still read the text? Can you sense that there is a light source there? Does this affect the nature of this scene? Of course it does.

It is still quite unbelievable that noone wants to do the simple checkerboard tests Darin is describing.
ChrisWiggles's Avatar ChrisWiggles
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Quote:
Originally Posted by armadillo View Post

Chris: I'm baffled. I explicitly said that the real world in 3D has huge contrasts. The point is that these contrasts cannot be visualized withing the human viewing angle at the same time with the same contrast and same acuity. Our acuity, color and contrast perception is localized to a small area of the retina called the fovea. We are also able to dynamically adjust our eyes to a wide range of incident light. But what cannot achieve is that we resolve the full contrast unless we move the region of interest to a particular area. So as we optimize our vision for a subimage of the entire visual field, the periphery is not resolved in acuity, color, and contrast. If you don't believe me, try and resolve color and contrast outside of the text you are currently reading on screen. It just doesn't work.

That is not the claim that you were making or the one that I was rejecting. The claim is that there is a limited ability to discern contrast through a very small angle. And that our peripheral vision is even worse than that. Therefore, there is no benefit to have a display that can create higher than the limited CR we can discern through very small angles. That is the essence of your line of argument, and that is ridiculous. We can move our eyes around across a single scene with limited or no iris adaptation and view huge ranges of contrast and discern small changes of luminance across this huge range of luminance across a single scene.

Quote:


As I also said, it would be very desirable to have displays match the real world contrast, because we could then inspect that image by moving our fovea to points of interest and adapt the contrast relevant to that area. This would all be within a single frame. But if you want to see the entire image within the fovea at the same time, it cannot be too large and will be limited by the CR your eyes have adjusted to.

This contradicts your earlier claims in the thread:
Quote:
Originally Posted by armadillo View Post

From reading through a couple of the papers cited in the above link, I would supect that for a 24 FPS movie, 300:1 contrast is more than ample and a higher contrast ratio would not be noticeable; from one paper it would seem that even ~100:1 is pushing it).


Quote:


As to the text that states you can discern details in a tree against the sunlight, I did that test and I can say that my eyes cannot resolve contrast next to the sun. As soon as I blank out the sun, the tree is clearly visible in high contrast.

Through what kind of viewing angle? If there is a sun in the sky somewhere in your peripheral vision, can you then make out details in darker portions of the scene? If you cannot, then that means you probably have some serious visual impairments and should not operate a motorvehicle. You should also see an optometrist.
ChrisWiggles's Avatar ChrisWiggles
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Quote:
Originally Posted by armadillo View Post

Darin: Check this link

http://www.cis.rit.edu/people/facult...p_9/ch9p1.html

at the bottom of the page, it'll give you the answer to your question.

You totally avoided Darin's questions.

Also, what are you referencing in this website? I don't see anything on that page that is relevant to your claims, or to Darin's questions.
HoustonHoyaFan's Avatar HoustonHoyaFan
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Quote:
Originally Posted by darinp2 View Post

A single receptor in the eye could have a range of 100:1 without adaptation while all receptors in the eye put together could have a much higher range (since different receptors can be acclimated to different levels). Do you agree or disagree with that?

IIMU that the receptors (rods and cones at the light facing part of the retina) have the ability to capture and discriminate a range from a few photons, up physical damage. AFAIK thats ~10^-6 6 to 10^8. It is the ganglion cells (neurons) at the back of the retina which have a limited light intensity dynamic range of <200:1. It is a many to many system, overlapping receptors are firing against overlapping ganglion cells.

IIMU that once a visual frame adaptation window is established, neurons within that frame fire a level within that frame, ( of course with redundacies and outliers).

The dynamic range limits of the ganglion cell (Barlow and Levick) was the first paper suggested to me.

It does not matter what the receptors receive, the ganglion cells are limited in their "reporting' capability to a range of light intensity < 200. I was told that CW has been < 100, but more recent work has suggested slightly higher.
ChrisWiggles's Avatar ChrisWiggles
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Quote:


It does not matter what the receptors receive, the ganglion cells are limited in their "reporting' capability to a range of light intensity < 200. I was told that CW has been < 100, but more recent work has suggested slightly higher.

But this is over very local areas, i.e. adjacent ganglia. This is what is described in the research in my understanding. Across the entire range of a scene the total range is far more significant.
HoustonHoyaFan's Avatar HoustonHoyaFan
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Quote:
Originally Posted by mark_1080p View Post

In my humble opinion, and I do make mistakes, you and HH are not applying the science properly.

If you point out specifically where I have misapplied the science, I will make corrections. I have stated that I am not a HVS researcher. I have been very clear that I am not concluding any display benchmark number from the HVS CR number.

I also will not put as much emphasis on the ANSI CR number
Quote:
Originally Posted by gregr View Post

...The ANSI contrast is just a figure of merit. You can't compare it to, or combine it numerically with the full-field contrast ratio to calculate intra-image contrast. Intra-image contrast is related to proximity and distribution,...


HoustonHoyaFan's Avatar HoustonHoyaFan
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Again from IMO the most respected display expert. I added the bold emphasis:
Quote:
Originally Posted by gregr View Post

Intra-image contrast has traditionally been measured using a 4x4 checkerboard pattern and an ANSI specified process that could have only been designed by a committee. I've explained this in other threads in the past so I won't detail it again here, but the ANSI process leads to measurement errors, poor repeatability, and produces higher contrast values in the least important parts of the picture (especially for non-CRT projectors), which are then weighted equally with the lower contrast values in the more important parts of the picture. So in my opinion, although the ANSI contrast ratio is just a figure of merit, it is about as bad a figure of merit as anyone could imagine (especially for non-CRT projectors). So for the last few years I have been using my own modified-ANSI contrast ratio measurement process (which I've detailed here previously), which I believe substantially corrects these issues. But the result is still just a figure of merit. i.e. It allows you to compare projector A vs projector B, but there is still no way to numerically compute the resulting intra-image contrast for any real image content. That is way beyond anything that could be done with a few test patterns and without very complex computations.

When we refer to intra-image contrast we are usually talking about contrast at fairly low frequencies. i.e. not the smallest image details. MTF is a way of measuring contrast vs spatial frequency isolated from the factors that affect contrast at low frequency, so it tells us about the sharpness and resolution of the projector independent of other factors. It takes some rather sophisticated equipment to measure MTF at high spatial frequencies.

http://www.avsforum.com/avs-vb/showt...03#post9315703
darinp2's Avatar darinp2
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Quote:
Originally Posted by HoustonHoyaFan View Post

It does not matter what the receptors receive, the ganglion cells are limited in their "reporting' capability to a range of light intensity < 200. I was told that CW has been < 100, but more recent work has suggested slightly higher.

I would appreciate you commenting on what I said back in post #149 in this thread:
Quote:
Originally Posted by darinp2 View Post

I'm not sure if any of these others are doing this, but if for instance a 400:1 CR would be perceived as 80:1 and an 8000:1 CR as 120:1 by the brain, then I would say that improvement beyond 400:1 had been perceived. In other words, 400:1 wouldn't have been enough for people to not see improvement, even if it registered as less than that.

My point is that if the brain perceives a lower contrast than is coming off the screen, but a higher contrast ratio off the screen would be perceived as better, then the images still haven't reached the point where improvements wouldn't be seen. And it is the CR off the screen that matters here as far as what displays need to do before we can no longer perceive improvements. I'm not clear whether your position is that something in our eyes can't report more than 200:1, or that improvements beyond 200:1 in an individual frame for the eye would not change what gets reported in a way that would be noticable to a human.

And just to be clear, that ganglion cell reporting of <200:1 isn't <200 levels, but a range of 200:1 in ratio of luminance from the brightest to the dimmest, right? Getting the junior researcher to answer the question I asked in post #165 about whether 4 levels could be seen at once in that example where two transitions are 400:1 apart would probably help. I'm still not clear whether your answer is that it would be impossible for the eye to "see" those at once and report that there are 4 levels (and not 3) where the transitions have a ratio of 400:1, but it seems like it has to be "No, it is impossible in a single frame" if your claim of <300:1 for a single frame stands.

--Darin
armadillo's Avatar armadillo
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Darin: Did you see the contrast adaptation in http://vision.psych.umn.edu/~gellab...nPaper_Kwon.pdf ? I just did it again, but I took the images and inverted them in a graphics program, so that the left spot is black. It works just as well as the original white. So I would suspect that in your experiment, as you concentrate on the brightness of the laser pointer and adapt to its brightness, the faintest object will indeed disappear.
HoustonHoyaFan's Avatar HoustonHoyaFan
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Quote:
Originally Posted by darinp2 View Post

My point is that if the brain perceives a lower contrast than is coming off the screen, but a higher contrast ratio off the screen would be perceived as better, then the images still haven't reached the point where improvements wouldn't be seen.

Agreed! I suspect we will need a Brightside type solution, before we could consider taxing the HVS.
Quote:
Originally Posted by darinp2 View Post

And just to be clear, that ganglion cell reporting of <200:1 isn't <200 levels, but a range of 200:1 in ratio of luminance from the brightest to the dimmest, right?

A discrimination range of <200:1 in ratio of luminance is my understanding.
Quote:
Originally Posted by darinp2 View Post

Getting the junior researcher to answer the question I asked in post #165...

I have recommended that she get a Pearl, from AVS, since she is interested in a pj and seems interested in my limited and likely incorrect explaination of the DI. Hopefully she will join AVS, and give you clearer answers than I have been able to.

She has cautioned me about comming to simplistic conclusions about HVS limitations based solely on luminance discrimination. The reality is that the retina is preprocessing and streaming multiple layers of info to the cortex in parallel. Luminance discrimination is just one layer. Edge, boundry and shape discrimination is likely in another layer, Color in another, Motion in another. The Visual Cortex is responsible for integrating this parallel stream of info and creating perception. Info in a layer may change our perception of info in another layer.
darinp2's Avatar darinp2
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Quote:
Originally Posted by armadillo View Post

Darin: Did you see the contrast adaptation in http://vision.psych.umn.edu/~gellab...nPaper_Kwon.pdf ? I just did it again, but I took the images and inverted them in a graphics program, so that the left spot is black. It works just as well as the original white. So I would suspect that in your experiment, as you concentrate on the brightness of the laser pointer and adapt to its brightness, the faintest object will indeed disappear.

I may have to try that, but you are still using the same receptors, right? What if you concentrate right on the plus for one side, but offset the + a little to the left or right for the other side, so that you are now using some different receptors for the circle? And how about leaving the left side as white, but making the right side black instead of gray, or putting a black circle within the gray circle?

And in my experiment I wouldn't concentrate on the laser pointer and adjust to its brightness. I would concentrate on something darker and leave the laser pointer and white square outside the exact center of my focus. Then if I could see transitions that were something like 20:1 above and 20:1 below, or even 80:1 above and 5:1 below at the same time, that would be 400:1 total.

--Darin
armadillo's Avatar armadillo
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Darin: Actually, in thinking about it some more, I don't know what the outcome of your experiment will be. There are several options and I freely admit that I cannot easily predict how the brain would process the image. There are several possibilities: 1. It could try and maintain the low contrast portions of the image by clipping the bright spot (possibly depending on the size of the spot); 2. it could indeed fade the lowest contrast into perceived black; 3. it could clip on either end.
darinp2's Avatar darinp2
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Quote:
Originally Posted by armadillo View Post

Darin: Actually, in thinking about it some more, I don't know what the outcome of your experiment will be. There are several options and I freely admit that I cannot easily predict how the brain would process the image. There are several possibilities: 1. It could try and maintain the low contrast portions of the image by clipping the bright spot (possibly depending on the size of the spot); 2. it could indeed fade the lowest contrast into perceived black; 3. it could clip on either end.

Just to be clear, your position is that I wouldn't be able to see all 4 levels at once though. Is that right? Your position seems to be that only the center of vision is 300:1 and in this experiment the person is not required to have all 4 levels in the center of their vision. They can move to a distance or gaze at a spot they choose that gives them the best chance of seeing all 4 levels at the same time.

Do you have projector? Could you get some black posterboard and a white laser pointer (or just modify one of the squares to have both 100 IRE and 80 IRE)?

--Darin
armadillo's Avatar armadillo
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Darin: Yes, you have to use the same receptors in order for adaptation to occur, although the adaptation is not actually happening in the receptors (but they are still connecting to the same interneurons). In fact, these are grouped into what people call receptive fields that partially overlap (at least that's what recall from physiology class). Anyway, if you concentrate on the low contrast area, than you won't see the faintest square disappear. It's like looking away from the sun. That's not a fair situation, since you are separating the contrast and looking at a subimage, not the entire image within your fovea. So you are indeed taking advantage of selective adaptation and not giving the laser the chance it deserves
darinp2's Avatar darinp2
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Quote:
Originally Posted by armadillo View Post

That's not a fair situation, since you are separating the contrast and looking at a subimage, not the entire image within your fovea. So you are indeed taking advantage of selective adaptation and not giving the laser the chance it deserves

I'm not sure if you are joking here or not. I don't have to have everything in the fovea for it to matter. If I can see the 4 levels then I can see them. If you claim that people can't see more than 200:1 or 300:1 or whatever in a full image and we can see transitions of 400:1 and beyond at one time, then things like "that isn't fair" won't make your claim true.

Once again, when looking for the most, if somebody comes up with things that you have to do in order to lower the amount you can see so that they can claim a lower limit, then they aren't looking for the most. Like only letting us consider things that are right next to each other.

I'm starting to get the feeling again that you are fine with all the information outside of the fovea blurring into nothingness, which isn't realistic and would be a problem (or weakness of the display). We don't need to be able to make out the exact details out there for that information to be relevant to our perception. Going back to the peripheral vision being best at detecting movement, if the CR in the periphery is small enough then movements that should have been detectable will not be. And that can also be a problem with a display that should have rendered a moving object with enough CR for us to detect it.

--Darin
armadillo's Avatar armadillo
09:17 PM Liked: 10
post #208 of 505
12-30-2006 | Posts: 108
Joined: Jul 2005
Darin: Ha!!! I just did a cool experiment. See for yourself. Make an image in PS or your favorite graphics app. Make it 600x600 with black background. Then create four equally size squares 0f 250x250 and place them on the image so that you reatin a 20 pixel distance. Set the brightness of the squares as topleft: 2% (adjust this value so that you just barely see it against the black background); topright 20%; bottomleft 40%; bottomright 60%. Finally create a fifth square of 250x250 and place right in the middle of the four and make that 100% brightness. You should place this square into a separate frame (or cut to the clipboard).

Now look at the center of the four squares. You should be able to see all of them at the same time, although the top left one will be ever so faint. You can even concentrate on the right or bottom bounds of that faint square to actually see the contrast. Now make the white center square visible (either by activating the layer or pasting it) and you will see that the top left square is gone. Make the white square invisible and the square will slowly reappear.

Edit: You can even even make all four squares faint (I can go up to brightness of 3% on my monitor). As soon as you make the white square visible, they all disappear for me. Even if I try to actively see the boundaries of the squares, which are still there, I cannot see them while the white square is present.
darinp2's Avatar darinp2
09:27 PM Liked: 75
post #209 of 505
12-30-2006 | Posts: 21,229
Joined: Sep 2003
Quote:
Originally Posted by armadillo View Post

Now make the white center square visible (either by activating the layer or pasting it) and you will see that the top left square is gone. Make the white square invisible and the square will slowly reappear.

I may try something like this later. We've already discussed how one paper talks about 4% of the energy washing out the other stuff and how people can make the bright parts big relative to other things if they want to make it seem like our vision is more limited than it is, or can make the bright parts smaller so that their energy is less and there is less washout to the dark side.

It seems like your experiment is pointing out one of the things I believe I've tried to talk about. You have a JND factor and if low CR makes the transition smaller than the JND, then you won't see it. But this is a problem with low CR and shows one of the reasons that high CR is needed in order to maintain more details.

--Darin
ChrisWiggles's Avatar ChrisWiggles
12:07 AM Liked: 15
post #210 of 505
12-31-2006 | Posts: 20,730
Joined: Nov 2002
Quote:


Darin: Actually, in thinking about it some more, I don't know what the outcome of your experiment will be. There are several options and I freely admit that I cannot easily predict how the brain would process the image. There are several possibilities: 1. It could try and maintain the low contrast portions of the image by clipping the bright spot (possibly depending on the size of the spot); 2. it could indeed fade the lowest contrast into perceived black; 3. it could clip on either end.

Or 4: you could be completely wrong and we could see all this at the same time without any difficulty at all.

I would bet money on 4, but since Darin already reported that to be the case, it's kind of a case of betting on a known outcome which isn't fair.

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