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post #1 of 10 Old 04-27-2012, 08:04 AM - Thread Starter
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I watch my Tv in the evening on weekdays & daytime at weekends.

How do I calibrate for the correct room lighting? I have read something about putting a light behind the television.

Does it make a difference whether I calibrate for daylight or night?
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post #2 of 10 Old 04-27-2012, 08:41 AM
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Quote:
Originally Posted by sefmiller View Post

I watch my Tv in the evening on weekdays & daytime at weekends.

How do I calibrate for the correct room lighting? I have read something about putting a light behind the television.

Does it make a difference whether I calibrate for daylight or night?

This article addresses your concerns fairly comprehensively: 'The Importance Of Viewing Environment Conditions In A Reference Display System.' Video displays offer controls and features that only attempt to compensate for competing viewing environment conditions. It it usually more effective to control the viewing environment than to expect picture adjustments to overcome the laws of physics or correct for the limitations of the human visual system.

"Correct room lighting" has been defined by motion imaging industry standards bodies for decades. This article lays out the essentials: 'D65 Video Bias Lighting Fundamental Theory and Practice.' Display calibration cannot completely correct for conflicting viewing environment elements. Therefore, it is recommended to solve such conflicts prior to calibrating the display, or engaging in critical viewing sessions, when you want the ultimate image quality and viewing experience possible.

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.
A Lion AV Consultants affiliate

"Advancing the art and science of electronic imaging"
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post #3 of 10 Old 04-27-2012, 09:56 AM
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Both of those articles are excellent for understanding the why's and wherefore's of bias lighting, albeit a bit technical for the uninitiated. The simple answer is a neutrally colored wall behind the tv with a light source as close to 6500k (accurately measured) as is possible.

Day and night calibration is a different matter so I'll let the professionals detail that one. Some folks seem to get by with one calibration and just change the backlighting a bit to compensate for the changing room conditions but it depends on what your room conditions are to start with. Vague I know, but....
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post #4 of 10 Old 04-27-2012, 10:20 AM
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Quote:
Originally Posted by sefmiller View Post

I watch my Tv in the evening on weekdays & daytime at weekends.

How do I calibrate for the correct room lighting? I have read something about putting a light behind the television.

Does it make a difference whether I calibrate for daylight or night?

if your set allows day and night modes you can have separate calibrations for each set of viewing conditions

however, reference viewing is best done in a dark room with a dim surround and a light, neutral colored wall behind the TV for best results

look for a 6500K light bulb that's not too bright and has a high CRI rating and place it behind your TV facing the wall when viewing TV at night

here a helpful link for properly implementing bias lighting

http://www.avsforum.com/avs-vb/showthread.php?t=1162578
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post #5 of 10 Old 04-27-2012, 10:47 AM
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Originally Posted by Otto Pylot View Post

Both of those articles are excellent for understanding the why's and wherefore's of bias lighting, albeit a bit technical for the uninitiated. The simple answer is a neutrally colored wall behind the tv with a light source as close to 6500k (accurately measured) as is possible.

Day and night calibration is a different matter so I'll let the professionals detail that one. Some folks seem to get by with one calibration and just change the backlighting a bit to compensate for the changing room conditions but it depends on what your room conditions are to start with. Vague I know, but....

Unfortunately, your "simple" answer leaves out critical information such as:

"Neutral" must be understood in video industry terms, not interior design terms. Interior designers will refer to all "earth tones" as neutrals. The recommended "neutral" color for display surrounds is that which reflects all colors equally (shades of gray, including white).

The light source must also be located behind the TV, so that it is not directly visible to the viewer, so that it "washes" the wall with illumination. This is necessary in order to avoid light reflecting off of the TV's screen.

The amount of illumination reflected from the wall is recommended to be about 10% of the brightest white the TV produces after it has been calibrated for dark viewing conditions.

It should be mentioned that so-called "day" and "night" calibration modes do not eliminate viewing environment problems. Any "day" mode cannot completely correct for the consequences of high ambient room lighting, or conflicting colors in the area surrounding the TV screen (within the observer's field of view). All a "day" mode can do is partially compensate for conflicting viewing conditions. Only a "night" mode has any chance of delivering a reference viewing experience.
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post #6 of 10 Old 04-27-2012, 11:34 AM - Thread Starter
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Do the room surfaces have to be black? This seems a bit of a grim colour, from an interior perspective, for a living room.

Should the bias lighting, behind the tv, be the only light in the room? So no traditional light shade hanging from the ceiling?

Do I need a luminance meter?
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post #7 of 10 Old 04-27-2012, 11:37 AM
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Quote:
Originally Posted by sefmiller View Post

Do the room surfaces have to be black? This seems a bit of a grim colour, from an interior perspective, for a living room.

Should the bias lighting, behind the tv, be the only light in the room? So no traditional light shade hanging from the ceiling?

Do I need a luminance meter?

actually lighter colors are best like some grays and whites

the bias light should be the only light in the room since you don't want any light hitting the screen directly

you don't need a luminance meter but certain test patterns on setup discs can help


day modes are a compromise but can offer a brighter overall image (higher peak light output and lower gamma) for when ambient lighting cannot be controlled/fully eliminated

night modes are for reference viewing and allow the TV to be set to a lower peak light output value and higher gamma, with the bias light being the only source of ambient light in the room
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post #8 of 10 Old 04-27-2012, 11:40 AM - Thread Starter
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To quote the article in the first reply: "Room surfaces should be a dark color that is neutral or nearly neutral. A flat black ceiling is highly recommended because the ceiling is usually the closest reflective room surface to the screen."

This recommends a dark color. Obviously, white isn't a dark color. I have no intention of having grey or black rooms in my house, though.
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post #9 of 10 Old 04-27-2012, 11:48 AM
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Originally Posted by GeorgeAB View Post

Unfortunately, your "simple" answer leaves out critical information such as:

That's why I put "simple" in quotes without a detailed caveat. No argument on your points, but I figured if the OP wanted to get into the details, he'd ask and others would offer more detailed, and exacting, explanations. This area can be daunting at times for someone who hasn't been here before so I thought it might be best to start off a little slow. Maybe I was wrong.
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post #10 of 10 Old 04-27-2012, 12:02 PM
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Quote:
Originally Posted by sefmiller View Post

To quote the article in the first reply: "Room surfaces should be a dark color that is neutral or nearly neutral. A flat black ceiling is highly recommended because the ceiling is usually the closest reflective room surface to the screen."

This recommends a dark color. Obviously, white isn't a dark color. I have no intention of having grey or black rooms in my house, though.

Your quote is from the 'For Front Projection Display Systems' section of the article. Different rules and recommendations apply for such systems. You will have fewer questions and less confusion if you pay closer attention to context when reading such articles or these forum posts.

No one has recommended a totally gray or black room to be necessary for your type of display. The wall behind the TV is what needs to be neutral. Other surfaces in the room can be nearly neutrals. If any wall is dark, the one opposite the TV screen is a most likely candidate. Doing this can help with screen reflections when watching TV in high ambient light conditions.
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