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post #2011 of 2022 Old Today, 09:18 AM
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Hi Javs, I've done perceptual studies on material appearance. We found using an HDR display that even at an intraframe dynamic range of 40,000:1 people can discern differences in things such as specular highlights on glossy surfaces. The increased brightness makes differences in gloss more salient. This was on a display with peak luminance just under 1,000 cd/m2.

You can't use adaptation as an argument for an upper limit on dynamic range. Color appearance depends on both relative luminance and absolute luminance. If you scale everything into a single constant range assuming perfect adaptation (adaptation is not perfect) then some of the perceived brightness and colorfulness gets sacrificed.
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post #2012 of 2022 Old Today, 11:09 AM
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Quote:
Originally Posted by Javs View Post
What you are saying is still not dynamic range of any sort its the iris in your eyes readjusting to a different range but still 14 stops or so wide. Clamped down if you will, or lower exposure if you will, but still 14 stops approx.

The wider range our eyes may be able to adapt to doesn't translate onto the screen, what you see on screen is always a simultaneous range is it not?
Even considering it as always a simultaneous range, it still takes a big dynamic range from a display overall to be able to do both bright content and dark content at the limits of human vision while people are watching different scenes. If a display could only do 16,000:1 total range that wouldn't be enough to match what humans can see if we assume 16,000:1 for human vision for single scenes.

Cameras can be used to shoot daylight scenes with ND filters on them and then dark scenes without filters on them, and the material we see is largely graded afterward (with or without digital effects) anyway.

Many scenes only use the lowest end of the range and if the display can't do high CR then while showing material that only uses the low end human vision can often see the deficiency. For instance, if one were to display a 5% video level on black checkerboard (like from the 2nd Spears and Munsil disc) on a display that had a total dynamic range of 16k:1 then the display probably wouldn't do over 50:1 for that image, where many displays with much higher dynamic ranges could provide much more simultaneous CR for that image.

Displays systems don't have to be able to do more than even 1000:1 ANSI CR to be HDR.

--Darin

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post #2013 of 2022 Old Today, 02:36 PM
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The question is not HDR, or HFR. Both of these are coming to UHD. The market will select/reject each of them over the next several years.

But back to the topic, will there be a UHD BD any time soon? If we are to see a UHD BD by this christmas, it sure seems like we should have heard of a finalized spec by now. Why hasn't that happened yet? Pretty soon, someone will deliver a high bitrate UHD streaming service, and UHD BD will become OBE.
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post #2014 of 2022 Old Today, 03:07 PM
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Originally Posted by rak306 View Post
The question is not HDR, or HFR. Both of these are coming to UHD. The market will select/reject each of them over the next several years.

But back to the topic, will there be a UHD BD any time soon? If we are to see a UHD BD by this christmas, it sure seems like we should have heard of a finalized spec by now. Why hasn't that happened yet? Pretty soon, someone will deliver a high bitrate UHD streaming service, and UHD BD will become OBE.
I'd say CES 2016 is the better bet for the big announcements.

Listen up, studios! Just say "NO" to DNR and EE!!
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post #2015 of 2022 Old Today, 03:10 PM
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I'm a bit tired of the industry as of late. Too many half baked ideas being thrown to the market. They are alienating the true early adopters.
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post #2016 of 2022 Unread Today, 05:20 PM - Thread Starter
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Quote:
Originally Posted by rak306 View Post
The question is not HDR, or HFR. Both of these are coming to UHD. The market will select/reject each of them over the next several years.

But back to the topic, will there be a UHD BD any time soon? If we are to see a UHD BD by this christmas, it sure seems like we should have heard of a finalized spec by now. Why hasn't that happened yet? Pretty soon, someone will deliver a high bitrate UHD streaming service, and UHD BD will become OBE.
From statements made by reps of the BDA at CES, and shortly thereafter, it appears the BDA will not announce the spec. by itself. Rather, they plan to announce both the spec. and the patent license package at the same time this summer. The spec. itself may be agreed some months before the patent license packet is finalized and members of the BDA (includes the BD player manufacturers) will not need to wait for the actual announcement to move forward with the development of their 1st generation UHD Blu-ray players.
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post #2017 of 2022 Unread Today, 05:40 PM
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Quote:
Originally Posted by EvLee View Post
Hi Javs, I've done perceptual studies on material appearance. We found using an HDR display that even at an intraframe dynamic range of 40,000:1 people can discern differences in things such as specular highlights on glossy surfaces. The increased brightness makes differences in gloss more salient. This was on a display with peak luminance just under 1,000 cd/m2.

You can't use adaptation as an argument for an upper limit on dynamic range. Color appearance depends on both relative luminance and absolute luminance. If you scale everything into a single constant range assuming perfect adaptation (adaptation is not perfect) then some of the perceived brightness and colorfulness gets sacrificed.
Can you elaborate a bit? I'm not sure I follow you. Are you saying people can see subtle variations on very bright objects, that are ~40k brighter than the dimmest object on the screen? How does one even get 40k:1 on the screen at the same time?

Even if that is true - it is not surprising, what would be surprising is if one could also discern subtle black levels at the same time that were physically located near the bright highlights.

Last edited by rak306; Today at 05:46 PM. Reason: added thought
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post #2018 of 2022 Unread Today, 06:46 PM
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Quote:
Originally Posted by rak306 View Post
Can you elaborate a bit? I'm not sure I follow you. Are you saying people can see subtle variations on very bright objects, that are ~40k brighter than the dimmest object on the screen? How does one even get 40k:1 on the screen at the same time?

Even if that is true - it is not surprising, what would be surprising is if one could also discern subtle black levels at the same time that were physically located near the bright highlights.
This is precisely my point. Couple links and quotes of interest. Remember, we are not talking total dynamic range here, we are talking what you can see in mixed APL scenes. I would also be interested to see some info on links on how we can see 40k:1 at once on a screen.

http://en.wikipedia.org/wiki/Human_eye#Dynamic_range

"The retina has a static contrast ratio of around 100:1 (about 6.5 f-stops). As soon as the eye moves it re-adjusts its exposure both chemically and geometrically by adjusting the iris which regulates the size of the pupil. Initial dark adaptation takes place in approximately four seconds of profound, uninterrupted darkness; full adaptation through adjustments in retinal chemistry (the Purkinje effect) is mostly complete in thirty minutes. The process is nonlinear and multifaceted, so an interruption by light merely starts the adaptation process over again."

http://www.practical-home-theater-gu...t-ratio-1.html

"It is the same with the eye; at any given instant, the eye can possibly see over a range of 400 to 800:1 in contrast detection. Some may even see up to 1,000:1 and possibly a little beyond but the eye would not detect any difference above approximately 1,000:1. For anything above that, the whites would be already too bright and the blacks would be too dark for the eye to distinguish any further detail.

The wider dynamic range of the eye is possible as once the eye moves (saccades), it re-adjusts its exposure both chemically and by adjusting the iris. Over time, it is possible for the eye to resolve a contrast ratio range (sort of the dynamic contrast range in HDTVs) of between 1,000,000 and 10,000,000:1.

However, the eyes' ability to detect contrast depends on the scene brightness, with the contrast sensitivity of the eye decreasing to about 8% of its maximum at low light levels; the eye sensitivity also decreases with lower contrast subjects.

To complicate matters, the eye Contrast Sensitivity Function (CSF) is not linear; in as much as it decreases with a decrease in brightness, there is a brightness level above which the eye contrast sensitivity falls once again. It is estimated that the sensitivity of the eye is some 600 times less in bright sunlight.

At low light levels, the eye is able to integrate image information over a period of some 15 seconds to be able to see dimly lit subjects (it is like when you increase the camera exposure time to record subject information during low light level conditions).

However, moving from one brightness range to another would take time for the eye to adapt. A 'dark-adapted' eye would be able to see a faint star in the sky, but this dark adoption process by the eye takes 30 minutes or so to complete - provided you haven't been exposed to bright sunlight during the day, otherwise, it may take even up to one hour for full adaptation to take place. Looking at a bright subject by a dark adapted eye would simply kill your night vision"


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post #2019 of 2022 Unread Today, 06:51 PM
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I'm a bit tired of the industry as of late. Too many half baked ideas being thrown to the market. They are alienating the true early adopters.
Completely agreed. It almost feels like desperation. Any half-baked idea to sell and promote...seemingly every so many months.

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post #2020 of 2022 Unread Today, 06:52 PM
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Quote:
Originally Posted by darinp2 View Post
Even considering it as always a simultaneous range, it still takes a big dynamic range from a display overall to be able to do both bright content and dark content at the limits of human vision while people are watching different scenes. If a display could only do 16,000:1 total range that wouldn't be enough to match what humans can see if we assume 16,000:1 for human vision for single scenes.

Cameras can be used to shoot daylight scenes with ND filters on them and then dark scenes without filters on them, and the material we see is largely graded afterward (with or without digital effects) anyway.

Many scenes only use the lowest end of the range and if the display can't do high CR then while showing material that only uses the low end human vision can often see the deficiency. For instance, if one were to display a 5% video level on black checkerboard (like from the 2nd Spears and Munsil disc) on a display that had a total dynamic range of 16k:1 then the display probably wouldn't do over 50:1 for that image, where many displays with much higher dynamic ranges could provide much more simultaneous CR for that image.

Displays systems don't have to be able to do more than even 1000:1 ANSI CR to be HDR.

--Darin
I see what you are saying, good points. Though, isnt that checkerboard display how they measure ANSI? My 300ES apparantly does ~450:1 on those, where are you getting 50:1 from? That seems way low.

Just goes to show ANSI contrast is the most important projector measurement of contrast...

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post #2021 of 2022 Unread Today, 07:25 PM
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Originally Posted by Ron Jones View Post
From statements made by reps of the BDA at CES, and shortly thereafter, it appears the BDA will not announce the spec. by itself. Rather, they plan to announce both the spec. and the patent license package at the same time this summer. The spec. itself may be agreed some months before the patent license packet is finalized and members of the BDA (includes the BD player manufacturers) will not need to wait for the actual announcement to move forward with the development of their 1st generation UHD Blu-ray players.

And to do that, they don't need a license. They do not need a license before they start selling the machines. But I am not optimistic about them selling machines before 1st Q 2016.

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post #2022 of 2022 Unread Today, 09:36 PM
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[quote=Javs;33643969]I see what you are saying, good points. Though, isnt that checkerboard display how they measure ANSI?[/qoute]It is the same layout (4x4), but what I mentioned was with the brightest rectangles at 5% video level instead of 100% video level. The ANSI CR checkerboard is an extremely bright pattern. For instance, somebody did some measurements on The Dark Knight recently and less than 1% of the frames measured from that were as bright as the ANSI checkerboard.

The checkerboard I mentioned is more representative of dark images, where our eyes can often see that the display is showing CR weakness.
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My 300ES apparantly does ~450:1 on those, where are you getting 50:1 from? That seems way low.
With a normal gamma 5% video level should be about 1/700th of white. That is darker than the "black" during that ANSI checkerboard where you get 450:1 from the projector (and even less off the screen). So, if your projector only had about 500:1 sequential also that 5%/0% checkerboard might only get 2:1 or 3:1 intra-image.

I got the 50:1 from calculating about 22:1 from the sequential CR of 16k:1 with 16k/700, then assuming some extra washout from the brighter rectangles and raising gamma some just out of black to make up for the low intra-image CR for that kind of image. The 50:1 was just a ballpark estimate of about the most I would expect from a display for that 5%/0% pattern with "only" 16k:1 sequential. Lower sequential and it would get even worse that that.
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Just goes to show ANSI contrast is the most important projector measurement of contrast...
I think it shows much the opposite. For instance, there was a Sony LCD that Sony tried to sell for mastering content. I measured one and the ANSI CR off the display was something like 480:1, with a sequential CR of about 520:1 (I would have to check my notes to get better numbers). This display did a horrible job with blacks for real video content. The CRT near it with much lower ANSI CR did much better at doing black for real video content.

The reason goes back to things like that 5%/0% checkerboard I mentioned, where sequential CR quickly became the limiting factor for intra-image CR. There are some people who must believe that ANSI CR tells us what intra-image CRs we will get with real content since it is an intra-image CR test, but that is a fallacy. Whichever is worse between ANSI CR and sequential CR on their own scales can be the limiting factor for intra-image CRs with real content.

I've attached an image from 3 different scenarios in my room with different combinations of ANSI CR and sequential CR off my screen. The image is a 4x4 checkerboard of about 16% video level on black. Here the low sequential CR off the screen for the highest system ANSI CR cases to do worse for this pattern than the scenario that had the lowest ANSI CR, but the highest sequential (on/off) CR.

Here is some data from The Dark Knight:

AVS APL Study - Adjunct to AVS Contrast Project

Showing that while less than 1% of the images were as bright as the ANSI checkerboards, about 23% of the images were as dark as my 16%/0% checkerboard (which results in about 1% Average Display Luminance after gamma).

--Darin
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