Using ambient light - improves image contrast perception? - AVS Forum
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post #1 of 15 Old 12-23-2013, 10:57 AM - Thread Starter
 
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I read about how adding ambient light, especially one coming behind the screen works on eye retinas and how human eye can only capture 600-800 CR image. I have a window right behind my TV and I open shutters just enough to get some light through. It really does make blacks seem blacker. I can barely tell where the the screen ends and bezel begins.when the background is pure black.

I hear some people say that their "which-ever pro-calibrated LCD TV" performs as well as their plasma TV during the day, but not at night. I take it ambient light is the reason for it. But does it really have an effect on eye retinas that make an LCD TV with 0.05 cd/m^2 black level and 2000:1 CR seem like it has a much higher contrast ratio? like a plasma TV? So, technically, plasmas only shine in a completely light-less room? Maybe that is the reason people prefer LCDs when they go to stores since plasmas are no longer as dim as they used to be, and since there is light all around - LCD image doesn't seem to be much worse, even though in dark rooms it is. I also hear plasmas flicker at 60Hz like LCDs flicker at 48Hz or CRTs flicker at 60Hz - true?

I also hear about ambient lights you can buy, but is there a way to make them with home supplies or lamps? Do they have to have special brightness to them? Positioning? Color?
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post #2 of 15 Old 12-23-2013, 11:06 AM
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Quote:
Originally Posted by MonarchX View Post

I read about how adding ambient light, especially one coming behind the screen works on eye retinas and how human eye can only capture 600-800 CR image. I have a window right behind my TV and I open shutters just enough to get some light through. It really does make blacks seem blacker. I can barely tell where the the screen ends and bezel begins.when the background is pure black.

I hear some people say that their "which-ever pro-calibrated LCD TV" performs as well as their plasma TV during the day, but not at night. I take it ambient light is the reason for it. But does it really have an effect on eye retinas that make an LCD TV with 0.05 cd/m^2 black level and 2000:1 CR seem like it has a much higher contrast ratio? like a plasma TV? So, technically, plasmas only shine in a completely light-less room? Maybe that is the reason people prefer LCDs when they go to stores since plasmas are no longer as dim as they used to be, and since there is light all around - LCD image doesn't seem to be much worse, even though in dark rooms it is. I also hear plasmas flicker at 60Hz like LCDs flicker at 48Hz - true?
Spend some time with the "sticky" threads at the top of this section of the forum. They are there for enduring educational value, not just "popularity." Many of your questions are answered there. This one in particular covers in detail your main point:, especially the last two paragraphs of the opening post:

'D65 Video Bias Lighting- Fundamental Theory And Practice'
http://www.avsforum.com/avs-vb/showthread.php?t=1162578
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post #3 of 15 Old 12-23-2013, 11:11 AM - Thread Starter
 
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I didn't even see those and I've been here for a while. Usually forums have Sticky threads at the top in large bold font for all to see.immediately.
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post #4 of 15 Old 12-23-2013, 11:17 AM - Thread Starter
 
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Is there a specific number as far as perceived contrast goes? For example, "2000:1 would appear as 10000:1 with ambient light" is an example, but with proper numbers, not the ones I just made up.
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post #5 of 15 Old 12-23-2013, 11:20 AM
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Originally Posted by MonarchX View Post

Is there a specific number as far as perceived contrast goes? For example, "2000:1 would appear as 10000:1 with ambient light" is an example, but with proper numbers, not the ones I just made up.
No.
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post #6 of 15 Old 12-23-2013, 11:25 AM
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I didn't even see those and I've been here for a while. Usually forums have Sticky threads at the top in large bold font for all to see.immediately.
That was an arbitrary decision by the moderators, perhaps due to the number of "stickies" that had accumulated. I don't consider the decision to be helpful to the readership, but I'm not a moderator.
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post #7 of 15 Old 12-23-2013, 11:37 AM - Thread Starter
 
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It was quite helpful, although I haven't gone through all the links within that thread. I just wish there was more specific info on lamps, where to get them or how to make them and also updated info on how plasma and LCD displays are perceived with ambient light. They demonstrated old technologies there - CRT and DMD.
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post #8 of 15 Old 12-23-2013, 11:53 AM
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Originally Posted by MonarchX View Post

It was quite helpful, although I haven't gone through all the links within that thread. I just wish there was more specific info on lamps, where to get them or how to make them and also updated info on how plasma and LCD displays are perceived with ambient light. They demonstrated old technologies there - CRT and DMD.
The most viewing environment tutorial information that I am aware of, along with practical solutions, and additional related links, can be found at my web site. All emissive type displays will benefit from the use of bias lighting. Flat panel displays are not different in that regard. The issue is an emissive video image as it's perceived by the human visual system. Front projection display systems are a separate category.
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post #9 of 15 Old 12-23-2013, 12:00 PM - Thread Starter
 
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I am sure they are because they need to be viewed in dark environment - movie theaters. I wonder what contrast ratio they have but regardless, I know that in reality blacks are gray in movie theaters but they are perceived pitch-dark blacks and 4K resolution movies look stunning in movie theaters like IMAX.
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post #10 of 15 Old 12-23-2013, 02:14 PM
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Originally Posted by GeorgeAB View Post


'D65 Video Bias Lighting- Fundamental Theory And Practice'
http://www.avsforum.com/avs-vb/showthread.php?t=1162578

can't believe I missed this. Very interesting, I always assumed that being adapted to higher ambient lighting would lower both blacks and whites. Turns out I was wrong. I'm reading through some of Fairchild's work right now.
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post #11 of 15 Old 12-23-2013, 02:57 PM
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Since the early days of Joe Kane's mission, he has been saying that the most frequently ignored element of proper display system setup is the viewing environment. It is still true today.

One of more frequent statements made by experienced calibrators that perpetuates this ignorance is: "Adjust your TV picture controls for the lighting conditions you usually watch in." The problem with this statement is the fact that no video display currently available can produce its best picture in high ambient lighting. Consumers have not been taught this reality for the most part. A video display should first be aligned for darkened room viewing. Alignment for brighter ambient lighting should be secondary in priority. Brighter room lighting unavoidably compromises, contaminates, and even can obscure the video image.

Properly implemented bias lighting is part of a reference viewing condition in color grading and mastering suites around the world. Reference imaging in the home must emulate professional practice to maximize fidelity.
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post #12 of 15 Old 12-23-2013, 03:00 PM - Thread Starter
 
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Where do you find such lamps with those exact specs though?

"1. The color of light should be as close as possible to the video white point of 'CIE D65' (loosely referred to as 6500 Kelvins) for color video viewing .
2. The color rendering index (CRI) is often published for a given lamp. A minimum CRI of 90 out of 100 is recommended for color reference applications."
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post #13 of 15 Old 12-23-2013, 03:03 PM
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Quote:
Originally Posted by MonarchX View Post

Where do you find such lamps with those exact specs though?

"1. The color of light should be as close as possible to the video white point of 'CIE D65' (loosely referred to as 6500 Kelvins) for color video viewing .
2. The color rendering index (CRI) is often published for a given lamp. A minimum CRI of 90 out of 100 is recommended for color reference applications."
Go back and read post #8.
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post #14 of 15 Old 12-23-2013, 04:43 PM - Thread Starter
 
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Can't find the link to your website anywhere - its not even in your profile.
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post #15 of 15 Old 12-23-2013, 04:49 PM
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