A Question about Bias Lighting - AVS Forum
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post #1 of 14 Old 03-30-2014, 12:27 PM - Thread Starter
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I purchased a reel of Adjustable White LED Strip Light(s) to use for bias lighting behind a Sony KDL-55W900A, mounted on a Peerless SAL770 articulating wall mount. Originally I was thinking I would 'ring' the perimeter of the display. But, I came across GeorgeAB's post, D65 Video Bias Lighting- Fundamental Theory And Practice, where he states, "7. Completely surrounding the monitor screen with illumination is not necessary to realize the principle benefits of the technique.", in response to the question of "What are the recommended elements of properly implemented bias lighting?"

Are there pros and cons to placing lights along the perimeter and/or in the center of a display? Are there any rules of thumb on the placement of bias lighting? In particular, when the lights are attached to the rear face of a display, on an articulating arm.


BTW, the panel is on an articulating arm, more to adjust the panels distance from the wall rather than to pan left or right.
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post #2 of 14 Old 03-30-2014, 02:34 PM
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Originally Posted by ShadesOfGrey View Post

I purchased a reel of Adjustable White LED Strip Light(s) to use for bias lighting behind a Sony KDL-55W900A, mounted on a Peerless SAL770 articulating wall mount. Originally I was thinking I would 'ring' the perimeter of the display. But, I came across GeorgeAB's post, D65 Video Bias Lighting- Fundamental Theory And Practice, where he states, "7. Completely surrounding the monitor screen with illumination is not necessary to realize the principle benefits of the technique.", in response to the question of "What are the recommended elements of properly implemented bias lighting?"

Are there pros and cons to placing lights along the perimeter and/or in the center of a display? Are there any rules of thumb on the placement of bias lighting? In particular, when the lights are attached to the rear face of a display, on an articulating arm.


BTW, the panel is on an articulating arm, more to adjust the panels distance from the wall rather than to pan left or right.
Pros and cons? As in all of the rest of life- it depends.
Rules of thumb? It depends.
In particular......? You don't provide enough information about your setup. Typically, wall mount brackets will block the spread of illumination from anything mounted on the back of a TV. Perhaps photos would help, but even they can fall short of communicating the right details. Often it requires some experimentation to get the best result.

There are two categories of considerations when implementing bias lighting. Most important is the fundamental technical principles of the technique. After that, will be the aesthetic considerations of how the illumination is distributed behind the display. I have yet to find any LED product that fulfills the first category. The most significant obstacle for LED is having sufficient spectral power distribution (SPD) or color rendering index performance (CRI).

Excellence in any endeavor requires getting the essential fundamentals right. If the fundamentals are compromised, it's like the proverbial house built upon sand. The foundation must be solid. A logical construct may appear reasonable, but cannot result in success if the premise is faulty.

Unfortunately, many consumers, and even professionals, start out with a convoluted conception of why bias lighting is worthy of consideration. Many think it's of value because it "looks cool" to have illumination coming from behind a video display. Others think its just for eye strain relief. The best way to implement the technique correctly is to fulfill the fundamental principles before addressing the aesthetic issues in a particular installation.

Sadly, there is no shortage of video display installations that have fundamental flaws preventing the best outcome. This is one reason why I usually try to dissuade my customers from mounting their TV on a wall. Another major flaw is having the wrong color of wall behind the display, or enclosing it in a niche or huge cabinet. Juggling such compromises complicates one's ability to get the best technical results.

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 14 Old 03-31-2014, 04:30 AM
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You nailed it George! After all, your the guru on the subject. I purchased the Ideal-Lume a few years back for behind my Panasonic 60GT30. I took your advice on ditching the wall mount (my previous Panny 50VT25 was wall mounted). My only problem with the Ideal-Lume is what you stated, my wall color is not ideal. This is my living room and I can't get away with neutral colors due to my wife. As you might guess, I haven't used the Ideal-Lume in awhile due to the wall color and the light illumination. My display is calibrated with about 35fl light output, we've been watching in total darkness when viewing movies and have not experienced eye fatigue.

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post #4 of 14 Old 03-31-2014, 04:47 AM
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I agree, the Ideal-Lume is probably the best choice, but most of use has less than perfect environments. My wall currently is not neutral ( i plan on rectifying that within the next year), but my main reason for a bias light once I moved to plasma was eye fatigue. I found that watching a long movie in a dark room if the move had many scenes that were light and dark then at the end of the movie my eyes were fatigued. At that time (2007) I picked up a LED light strip from Ikea, which was far from ideal as it cast a very yellowish light, but my eyes were no longer fatigued. This year I picked up the Antec LED strip bias light and it is great. Even Chad B. commented on how good the color was, he said it was lacking green, but otherwise was a decent bias light. I run it along the back top of my VT60 a few inches down. It casts an even light across the top back wall and a subtle light along the sides and bottom. With my VT60 calibrated to 38fl it is awesome and being USB it turns on and off with the TV. My second VT60 in the basement gym has same bias light and looks great mostly because the wall is white.
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post #5 of 14 Old 03-31-2014, 05:36 AM
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Originally Posted by kluken View Post

Even Chad B. commented on how good the color was, he said it was lacking green, but otherwise was a decent bias light. I run it along the back top of my VT60 a few inches down. It casts an even light across the top back wall and a subtle light along the sides and bottom. With my VT60 calibrated to 38fl it is awesome and being USB it turns on and off with the TV. My second VT60 in the basement gym has same bias light and looks great mostly because the wall is white.

I'm quite surprised at that as the Antec's are actually magenta.
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post #6 of 14 Old 03-31-2014, 08:36 AM
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I'm quite surprised at that as the Antec's are actually magenta.

Lacking green = too magenta ?

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post #7 of 14 Old 03-31-2014, 10:48 AM
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Originally Posted by kluken View Post

... but my main reason for a bias light once I moved to plasma was eye fatigue.

yep, I recently bought a cheap led lamp from canadian tire for that very reason. Ideally I'd have a lamp that was closer to D65 and had good CRI, and have neutral colors on the back wall, but for now that is impossible smile.gif

But I can now watch video on my FW900 without eye fatigue which is great!
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post #8 of 14 Old 03-31-2014, 01:26 PM
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Originally Posted by ThePrisoner View Post

You nailed it George! After all, your the guru on the subject. I purchased the Ideal-Lume a few years back for behind my Panasonic 60GT30. I took your advice on ditching the wall mount (my previous Panny 50VT25 was wall mounted). My only problem with the Ideal-Lume is what you stated, my wall color is not ideal. This is my living room and I can't get away with neutral colors due to my wife. As you might guess, I haven't used the Ideal-Lume in awhile due to the wall color and the light illumination. My display is calibrated with about 35fl light output, we've been watching in total darkness when viewing movies and have not experienced eye fatigue.
Here we have a classic quandary! Females of the species are actually more sensitive to color than the male. Their retinas have more cones than men. This makes women biologically equipped to better distinguish between, and appreciate more readily, subtle differences in colors than their mates. Unfortunately, physiology and biology don't inherently foster an appreciation for logic and reason.

Ever really looked at a major departments store's makeup department? How many shades of pink, beige, coral, etc., do you see there? If the store lighting was changed significantly, all those color samples would look substantially different. Would your wife care? Most would.

Color selection in wardrobe items, makeup, hair color, etc., has been developed into a fine science in the fashion industry. Most of it is based upon complexion. How the color of a garment interacts with the color composition of a woman's face/eyes/hair is at issue. Certain colors are "unflattering" with a particular woman's type of complexion. It's a perceptual issue for anyone viewing the woman.

These exact same points can be made when it comes to surrounding a painting, photograph, video display, etc, with any particular color. The only way to avoid unflattering interactions between the image on a video display and its environment is to surround the TV or monitor with a neutral color (any shade of gray- from near black to white). It's not the entire room that has to be neutral, just the wall that is within the observer's field of view when watching the display. Truly neutral colors complement any other color near it, because neutrals reflect all other colors equally.

Common decorator practice in designing rooms includes having most of the walls a near white color for good light reflection, but one wall a more vivid accent color to complement other design elements (carpet, furniture, drapes, etc.). Unfortunately, I've seen many times where the TV will be placed in the middle of the accent wall. This is just plain ignorance on the part of the designer. Of all the walls to choose for the accent color, the TV wall is the worst. Surrounding a video display with any color other than neutral will skew the color perception of the viewer. The color of the surround will be subtracted from the video image. More saturated color in the surround will increase this effect. Less colorful surrounds have less effect.

Room lighting also affects the perception of the surround, as well as how the image on the screen is perceived. The intensity and color of ambient lighting in a video viewing environment impact the viewing experience. Pick the wrong elements, and the picture quality of a video system will be unavoidably flattered or distorted/contaminated/compromised/disrupted/diminished. There are demonstrations of this phenomenon included in this video interview with Scott Wilkinson: http://www.avsforum.com/t/1499286/the-room-is-a-video-component-with-alan-brown .

How many walls are in your house? Tell your wife she has control of all of them.............except one. You get one wall- she gets all of the rest.
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post #9 of 14 Old 03-31-2014, 02:02 PM
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How many walls are in your house? Tell your wife she has control of all of them.............except one. You get one wall- she gets all of the rest.

Funny you should mention that. We just remodeled our family room/kitchen and I got exactly one wall to pick the paint color. Whew!
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post #10 of 14 Old 03-31-2014, 03:25 PM
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Lacking green = too magenta ?

True. From memory with the colorimeter red was really poor reading on it low 20s and blue was through the roof. I'm pretty sure somebody took an accurate reading of the Antec lights here.

Those Antec's are better than the other LEDs.
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post #11 of 14 Old 03-31-2014, 04:53 PM
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Originally Posted by GeorgeAB View Post

Here we have a classic quandary! Females of the species are actually more sensitive to color than the male. Their retinas have more cones than men. This makes women biologically equipped to better distinguish between, and appreciate more readily, subtle differences in colors than their mates. Unfortunately, physiology and biology don't inherently foster an appreciation for logic and reason.

Ever really looked at a major departments store's makeup department? How many shades of pink, beige, coral, etc., do you see there? If the store lighting was changed significantly, all those color samples would look substantially different. Would your wife care? Most would.

Color selection in wardrobe items, makeup, hair color, etc., has been developed into a fine science in the fashion industry. Most of it is based upon complexion. How the color of a garment interacts with the color composition of a woman's face/eyes/hair is at issue. Certain colors are "unflattering" with a particular woman's type of complexion. It's a perceptual issue for anyone viewing the woman.

These exact same points can be made when it comes to surrounding a painting, photograph, video display, etc, with any particular color. The only way to avoid unflattering interactions between the image on a video display and its environment is to surround the TV or monitor with a neutral color (any shade of gray- from near black to white). It's not the entire room that has to be neutral, just the wall that is within the observer's field of view when watching the display. Truly neutral colors complement any other color near it, because neutrals reflect all other colors equally.

Common decorator practice in designing rooms includes having most of the walls a near white color for good light reflection, but one wall a more vivid accent color to complement other design elements (carpet, furniture, drapes, etc.). Unfortunately, I've seen many times where the TV will be placed in the middle of the accent wall. This is just plain ignorance on the part of the designer. Of all the walls to choose for the accent color, the TV wall is the worst. Surrounding a video display with any color other than neutral will skew the color perception of the viewer. The color of the surround will be subtracted from the video image. More saturated color in the surround will increase this effect. Less colorful surrounds have less effect.

Room lighting also affects the perception of the surround, as well as how the image on the screen is perceived. The intensity and color of ambient lighting in a video viewing environment impact the viewing experience. Pick the wrong elements, and the picture quality of a video system will be unavoidably flattered or distorted/contaminated/compromised/disrupted/diminished. There are demonstrations of this phenomenon included in this video interview with Scott Wilkinson: http://www.avsforum.com/t/1499286/the-room-is-a-video-component-with-alan-brown .

How many walls are in your house? Tell your wife she has control of all of them.............except one. You get one wall- she gets all of the rest.

George, I always enjoy reading your posts. Maybe if we do our basement over I could finally have a neutral colored wall!

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post #12 of 14 Old 05-17-2014, 12:50 AM
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Originally Posted by GeorgeAB View Post

These exact same points can be made when it comes to surrounding a painting, photograph, video display, etc, with any particular color. The only way to avoid unflattering interactions between the image on a video display and its environment is to surround the TV or monitor with a neutral color (any shade of gray- from near black to white). It's not the entire room that has to be neutral, just the wall that is within the observer's field of view when watching the display. Truly neutral colors complement any other color near it, because neutrals reflect all other colors equally.

Common decorator practice in designing rooms includes having most of the walls a near white color for good light reflection, but one wall a more vivid accent color to complement other design elements (carpet, furniture, drapes, etc.). Unfortunately, I've seen many times where the TV will be placed in the middle of the accent wall. This is just plain ignorance on the part of the designer. Of all the walls to choose for the accent color, the TV wall is the worst. Surrounding a video display with any color other than neutral will skew the color perception of the viewer. The color of the surround will be subtracted from the video image. More saturated color in the surround will increase this effect. Less colorful surrounds have less effect.

Room lighting also affects the perception of the surround, as well as how the image on the screen is perceived. The intensity and color of ambient lighting in a video viewing environment impact the viewing experience. Pick the wrong elements, and the picture quality of a video system will be unavoidably flattered or distorted/contaminated/compromised/disrupted/diminished. There are demonstrations of this phenomenon included in this video interview with Scott Wilkinson: http://www.avsforum.com/t/1499286/the-room-is-a-video-component-with-alan-brown .

George,

One question of you that I haven't been able to nail down in my reading. If I have a color not on the white to gray scale, in this case a cream that I am working to identify on the munsell color spectrum to better understand its properties; and if this (assumed) non-neutral color will tint the 6500K bias light that is reflected to the viewer, should I explore using bias lights of colors temps other than 6500K to create a reflected light that comes closer to 6500K as perceived from the viewer post reflection off the wall? Would any of the calibration and color measurement tools that a calibrator carries be helpful in measuring the reflected light? or in helping to determine if a different color temp is needed and which way to go with the temp?

Thanks for your thoughts!
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post #13 of 14 Old 05-17-2014, 02:14 PM
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Originally Posted by GeorgeAB View Post

These exact same points can be made when it comes to surrounding a painting, photograph, video display, etc, with any particular color. The only way to avoid unflattering interactions between the image on a video display and its environment is to surround the TV or monitor with a neutral color (any shade of gray- from near black to white). It's not the entire room that has to be neutral, just the wall that is within the observer's field of view when watching the display. Truly neutral colors complement any other color near it, because neutrals reflect all other colors equally.

Common decorator practice in designing rooms includes having most of the walls a near white color for good light reflection, but one wall a more vivid accent color to complement other design elements (carpet, furniture, drapes, etc.). Unfortunately, I've seen many times where the TV will be placed in the middle of the accent wall. This is just plain ignorance on the part of the designer. Of all the walls to choose for the accent color, the TV wall is the worst. Surrounding a video display with any color other than neutral will skew the color perception of the viewer. The color of the surround will be subtracted from the video image. More saturated color in the surround will increase this effect. Less colorful surrounds have less effect.

Room lighting also affects the perception of the surround, as well as how the image on the screen is perceived. The intensity and color of ambient lighting in a video viewing environment impact the viewing experience. Pick the wrong elements, and the picture quality of a video system will be unavoidably flattered or distorted/contaminated/compromised/disrupted/diminished. There are demonstrations of this phenomenon included in this video interview with Scott Wilkinson: http://www.avsforum.com/t/1499286/the-room-is-a-video-component-with-alan-brown .

George,

One question of you that I haven't been able to nail down in my reading. If I have a color not on the white to gray scale, in this case a cream that I am working to identify on the munsell color spectrum to better understand its properties; and if this (assumed) non-neutral color will tint the 6500K bias light that is reflected to the viewer, should I explore using bias lights of colors temps other than 6500K to create a reflected light that comes closer to 6500K as perceived from the viewer post reflection off the wall? Would any of the calibration and color measurement tools that a calibrator carries be helpful in measuring the reflected light? or in helping to determine if a different color temp is needed and which way to go with the temp?

Thanks for your thoughts!
In theory, it should be possible to correct for a surface color with the right light source. However, in practice, the challenge is coming up with the right light. Cost is always a practical consideration, both in time and money. The simple and affordable solution is to simply provide a neutral wall color or fabric covering. If one's priority is how the room looks when not viewing a video display, why bother? If the priority is video image accuracy, a non-neutral wall color will be troublesome.

I have experimented with adjustable RGB LED arrays, measuring with a spectroradiometer. Their bandwidths for each color diode are so narrow that results typically just look odd to the eye when viewing the reflected results. Spectral power distribution is quite poor when using LEDs in the present state of the technology. Advances in color rendering have been made with LEDs, but cost is high. Metal halide lamps are far superior for daylight color simulation. Heat and dimming are the challenges with that technology.

I have also experimented with color filters a lot. Results have not been satisfactory with that method, either. The steps between various options are not fine enough in most applications. Combining filters can help, but too much light output can be lost along the way.
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post #14 of 14 Old 05-17-2014, 03:13 PM
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Originally Posted by GeorgeAB View Post

In theory, it should be possible to correct for a surface color with the right light source. However, in practice, the challenge is coming up with the right light. Cost is always a practical consideration, both in time and money. The simple and affordable solution is to simply provide a neutral wall color or fabric covering. If one's priority is how the room looks when not viewing a video display, why bother? If the priority is video image accuracy, a non-neutral wall color will be troublesome.

I have experimented with adjustable RGB LED arrays, measuring with a spectroradiometer. Their bandwidths for each color diode are so narrow that results typically just look odd to the eye when viewing the reflected results. Spectral power distribution is quite poor when using LEDs in the present state of the technology. Advances in color rendering have been made with LEDs, but cost is high. Metal halide lamps are far superior for daylight color simulation. Heat and dimming are the challenges with that technology.

I have also experimented with color filters a lot. Results have not been satisfactory with that method, either. The steps between various options are not fine enough in most applications. Combining filters can help, but too much light output can be lost along the way.

Thanks for your thoughts. The wall in question is part of my combined family/kitchen/dining room so paint is not a great option. However, much of the viewing is non-critical and I have enough other lighting issues during those times. Sounds like an approach where I can drape some neutral color fabric during critical movie viewing might be a way to go.
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