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Reid Malenfant
07-01-2011, 19:55
I'm not sure how many people have heard about or actually use this so i figured i'd get a post up about it :)

D65 back or bias lighting actually improves the picture that you'll see on your TV & help prevent eye strain. The proof of the pudding is in the eating so they say. As i own a Philips TV with Ambilight i can have lots of pretty colours blown on to the wall behind the TV that is supposed (according to Philips) to enhance the viewing experience. These are or can be set to match colours that are produced around the screen edges. What it actually does is distort the colour that you view on the screen. I'll see if i can find something to demostrate this, i think you'll be pretty surprised, i know i was :eek:

Having discovered this & being lucky that i happen to have Ambilight spectra 3 i soon discovered that i could set the Ambilight to very close to the colour temperature 6500 Kelvin (6500K - D65) & lock it there. The difference this made to viewing was pretty astounding to say the least. No light need to be on in the room as the Ambilight supplies enough from behind the screen to do whatever you need to do. It also improves the contrast ratio :mental:

All that is needed to carry this out is some kind of 6500K source of light with a colour rendering index (CRI) of 90 or more. Something like a 15W triphosphor 6500K energy saver right hard up against the back of the TV itself should do the trick for a 42" TV ;) Other tubes that could be used include older halophosphate tubes such as "Northlight" at about 20W due to it being less efficient.

What you are aiming for is about 10% of full screen white brightness as a maximum ;) Smaller TVs will need less powerful tubes, larger TVs a bit more..

Here is a bit of bumph i just found just so you don't think Mark has lost the plot :eyebrows:

What are the recommended elements of properly implemented bias lighting?

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 ['D50,' the 'E' point, or ~5400K in other specific applications].
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.
3. The illumination should originate from behind the frontal plane of the screen to avoid reflections, haze, and glare (which interfere with, contaminate, and obscure the image).
4. The lamp itself should not be directly visible to the viewer, but rather the illumination should be reflected by surrounding surfaces, such as the wall behind the monitor.
5. The brightness of the reflected illumination should be 10% or less of the brightest white the monitor is adjusted to (calibrated for a dark environment).
6. Surrounding surfaces within the observer's field of view of the monitor screen should be neutral in color (gray to white), see: Munsell Color Order System's neutral value scale.
7. Completely surrounding the monitor screen with illumination is not necessary to realize the principle benefits of the technique.
8. It usually works best for the lamp to be mounted on the back of the monitor or TV cabinet (rather than on the wall), in order for the illumination to spread out over some distance.
9. Test patterns for adjusting bias lighting relative to the monitor screen are available in many optical disc programs for setting up home entertainment systems (see: 'Avia II- Guide to Home Theater,' 'Digital Video Essentials' series, etc.).

What are the proven benefits of correctly implemented bias lighting?

1. Reduces or eliminates eye strain and viewing fatigue in dark viewing conditions.
2. Eliminates image contamination due to reflections, haze and glare on the screen from conventional room lighting.
3. Enhances perceived black levels, contrast ratio, and picture detail by enabling dark adapted viewing.
4. Preserves correct color perception of the video image by the viewer.
5. Prolongs monitor phosphor life by enabling dark room viewing and lowering of screen brightness requirements (phosphors are used in CRTs, plasmas, and LCDs with CCF or white LED back lighting).
6. Provides a low level of illumination in the room for movement and peripheral activities.

Says who?

The following organizations are confirmed to define, recommend, specify, and/or use the technique of video bias lighting:

The Society of Motion Picture and Television Engineers (SMPTE)
The International Organization for Standardization (ISO)
The International Telecommunications Union (ITU)
The National Institute of Standards and Technology (NIST)
The Metropolitan Museum of Art
Industrial Light and Magic (ILM)
The Imaging Science Foundation (ISF)
THX, Ltd.
Electronic Arts (EA)
by deluxe
Microsoft Corporation
Image Entertainment
Universal Studios
PostWorks
Joe Kane Productions
Ovation Multimedia
DisplayMate Technologies
CNET Labs
Radical Games
Factor5 Studios
High Moon Studios
CinRam
Rev13 Films
Advanced Television Evaluation Lab- Communications Research Centre- Canada
Apple Corporation
Filet Post Production
Post and Beam
Cheyenne Mtn. Entertainment
Zombie Studios
CBS Television
Deluxe Digital Studios
Splice Here
Slant Six Games
New Hat LLC
Roush Media
Samsung Germany
Digital Film Lab- Denmark
Nice Shoes, VFX New York
Desperate Housewives, Editorial
Rockhopper Post
Live Nation Studios
LionAV Consultants
Avical
Technicolor-NY
Technicolor-Canada
Max Post
Bandito Brothers Studio
Chainsaw Edit
Twin Cities Public Television
Colorflow Post
ABC Television
The Moving Picture Company



Courtesy of this site here (http://www.allquests.com/question/4233037/D65-Video-Bias-Lighting-Fundamental-Theory-And-Practice.html)

sburrell
11-08-2011, 13:22
Funnily enough I read something about this recently when reading up on how to calibrate my TV. As a result I now use an Ikea lamp behind my TV at night as my sole source of light. I don't think it's the correct colour temperature or anything, but it's a nice start.

Something you didn't mention was that cinema auditoriums implement side-lighting using this principal - the auditorium is never allowed to be lit solely by the movie. This convinced me to give it a try.

I hope others give this thread a read, because I find it makes a very pleasant difference to my viewing experience, and I've not even implemented this according to the defined specs.

It actually makes me think I should do the same for my computer monitor - I often play games into the night in an otherwise unlit room, and can vouch for the sensation of eyestrain. Hmm, may go out today and try to source the right equipment...

:)

HighFidelityGuy
11-08-2011, 13:42
Hmm, sounds interesting. Could this be done with LED's to make a low power consumption version?

EDIT: Scrap that, a quick eBay search tells me you can....

sburrell
11-08-2011, 13:50
I've just been phoning around, and found this for under 4:
http://www.amazon.co.uk/PureLite-Natural-Daylight-Bulb-Screw/dp/B004GAXCQY
On another website it was described as a 6500K bulb, though I can't find a manufacturer's website to confirm.

HighFidelityGuy
11-08-2011, 13:54
Here's an LED one that states 6500K: http://www.energybulbs.co.uk/products/Day+Light+Bulbs/Daylight+GU10+Bulbs/Economy+Daylight+GU10+Bulbs/Economy+Low+Energy+GU10+7W+Daylight/2876887848

sburrell
11-08-2011, 15:41
I just picked up one of these (http://www.ecat.lighting.philips.com/l/genie/lp_cf_ceconcfg_eu_fa_gb_lp_prof_atg/cat/gb/?lpType=Lam) in John Lewis for 2.10 - 11W (50W), 590lumens, 6500K, along with a suitable wee lamp. I got the lowest lumen emitting bulb I could find, to try to aim for the 10% total screen brightness value you referred to (I calibrated my display to 100cd/m^2, so knowing the size of the screen I imagine I could actually calculate the exact values I need, right?)

I had a chance to test the bulb whilst in the store and I was astonished at how blue it appeared against the rest of the store lighting - I calibrated my own monitors to 6500K and don't recall them being that blue, but then perhaps it was the contrast with the store lighting that emphasised it?

Anyway, I'll be testing this out this evening when I get in, replacing what must be a rather warm bulb in the Ikea lamp for this one - should be interesting!

I was reminded of something a step-uncle showed to me once. He was a sufferer of S.A.D. and had a light box for that reason, and he demonstrated the effect it had on colours when viewing the art on the walls of his living room - more were visible, especially in the purples.

Whilst I realise that most TVs are back-lit, I suppose there's an element of reflection to, so ambient light temperature must have some bearing on the viewing experience.

Anyway, I'll report back with impressions later. :)

HighFidelityGuy
11-08-2011, 20:56
I remembered I had a couple of LED GU10 bulbs spare that I found to be too blue/white for use as a normal room light. So I stuck them in some spare up-lighters and mounted them behind my TV pointing at the wall.

Here's what it looks like:

With one light:

http://i2.photobucket.com/albums/y48/DTM2000/Hi-Fi/Singlerear.jpg

With two lights:

http://i2.photobucket.com/albums/y48/DTM2000/Hi-Fi/Twinrear.jpg

They both look a bit brighter in the photo's than in real life and the ring shape is less prominent too. No other lights were on in the room. I can't decide whether one or two bulbs look best yet but I think two. What do you guys think? :hmm:

HighFidelityGuy
11-08-2011, 21:04
Here's the temporary setup behind my TV:

http://i2.photobucket.com/albums/y48/DTM2000/Hi-Fi/Rearview.jpg

sburrell
11-08-2011, 21:19
Well, I guess it depends what you find better on the eye. I'm cognisant that Mark specified a 10% of total screen brightness for the ambient lighting - that's pretty low, according to my colorimeter. I'd go with the single bulb for that reason.

I set up mine and found the 50W output of the 11W bulb too much, so I've covered the top of the shade with a speaker grille from my Monitor Audios, and it's much better.

https://lh3.googleusercontent.com/-sv88DaJPNq0/TkRGYxUT6PI/AAAAAAAAASI/y7X-AmgivjI/s800/ambient.jpg

I like it. I think it _is_ easier on the eyes. I'm going to live with it a see how things go :) I'll have to find a better way of mounting the lamp round the back though - the box it's on just now reflects too much light. I'll try to find some material (perhaps felt) to cover the box tomorrow.

sburrell
17-08-2011, 21:33
I removed the magnolia carpeting from the fireplace and replaced it with some beige upholstery fabric, and I think it looks a lot better. The magnolia was too reflective and, well, the cats had been at it so it was getting tatty. Here's how it looks now:
https://lh5.googleusercontent.com/-mrbopNiiSV0/TkwzFY3TO4I/AAAAAAAAASU/Oglm3uc-lsQ/s800/IMG_0381.JPG
Neater and less reflective, and the colour strikes me as being more auditorium-like.

Oh, and yes, that is Van Damme - his nipples talk to him when it gets cold. :lol: Probably one of the few ad campaigns that actually makes me want to buy the related product! :)

Reid Malenfant
17-08-2011, 21:40
Pleased to see a few people have discovered this thread :eyebrows:

There is definate eyestrain reduction & enough light to see what you are doing without messing up the picture ;) Contrast actually appears to improve, though obviously it can't in reality - but blacks look blacker!

Wouldn't be without it on any future TV, if it doesn't have Ambilight i'll be going for small 6500K CFLs myself :)

sburrell
20-08-2011, 02:22
Any advice forthcoming or linkable regarding a good way to paint your ceiling? I'm looking for a colour that's suitable both for improving movie viewing and for general daily living. Something that's a good compromise. Currently bright white with magnolia walls.

colinB
20-08-2011, 11:49
I just checked my bulb at the back of the tv. This is the one i got after starting a similar thread if you remmeber Mark. Its only 2700k.
Im searching for a 6500k bulb ( not tube ) and cant find any that go above 85 cri.

Reid Malenfant
20-08-2011, 16:29
That's about as good as you'll get Colin :rolleyes: If you go over to a tube you might find Northlight tubes which have a CRI of over 90, but that's about it ;) Trouble is they are old Halophosphate (rather than tri-phosphor) tubes so less efficient & they last for considerably less time.

Reid Malenfant
20-08-2011, 16:31
Any advice forthcoming or linkable regarding a good way to paint your ceiling? I'm looking for a colour that's suitable both for improving movie viewing and for general daily living. Something that's a good compromise. Currently bright white with magnolia walls.
No idea, mine certainly isn't ideal either & i have a projector & the screen is on a white wall :doh: Needs to be dark in reality...

Gazjam
30-09-2011, 09:03
Just caught this thread, going for the bias lighting with my 50" plasma, but unsure of which of two options to take and wonder if anyone can advise please?
I've tracked down these two online;

1: 6500k 5w bulb, CRI of 82
2: 6000K 15w bulb, CRI of 95

I will be trying it on the cheap at first by sticking a small lamp behind the tv panel to light the back wall, so just buying the best bulb for this particular setup.

What would be best?
*One or Two small lamps behind TV with the 5w bulbs...
*One lamp behind TV with the 15w bulb...

Will 15w be too bright for this application, its nigh on the same as a 100watt bulb?
Also, Whats more important in this situation, closeness to 6500K or a CRI value of 90+. The 5w bulb seems ideal (and cheaper too!) bit will a CRI of 82 be worse than the other bulb, which is three times brighter?

...or what about something completely different and marine tank flourescent at 6500k high CRI?
My plasma is about a foot away from the wall so have the room to stick a tube behind there.
Just not sure how I would mount it?
The lamp idea sounds a good start though as long as its effective...

Yup, its the usual FUD before trying something new... :)


ta.

colinB
30-09-2011, 09:34
I went for the 15w bulb and apart from the annoying shine from the bulb on the tv base it works very well. Even with my new varifocals my eyes are relaxed when i switch of the room lights :)

Mark Grant
30-09-2011, 10:37
Some of the 6500K bulbs appear too blue for me.

Has anyone found any reasonably priced RGB led strips with a decent controller that can be set to any colour ?

This kind of LED strip:
http://www.led-tape.com/led-strips/high-colour-changing-rgb

http://www.led-tape.com/led-strips/colour-changing-rgb

Probably with a DMX controller unless there is another way to have any colour and easy to control to preset colours etc:
http://www.led-tape.com/dmx-control

-

DaveK
30-09-2011, 11:48
If those light boxes they sell to treat SAD give out light of the correct wavelength to aid TV viewing it might be a cheaper (and safer for some) option to buy one ready made.

colinB
30-09-2011, 11:55
Years back in my store i started selling these bulbs that were meant to be good for SAD. They were silly prices and when i tested one at home they were very blue.

YNWaN
01-10-2011, 00:52
What are the proven benefits of correctly implemented bias lighting?

1. Reduces or eliminates eye strain and viewing fatigue in dark viewing conditions.
2. Eliminates image contamination due to reflections, haze and glare on the screen from conventional room lighting.
3. Enhances perceived black levels, contrast ratio, and picture detail by enabling dark adapted viewing.
4. Preserves correct color perception of the video image by the viewer.
5. Prolongs monitor phosphor life by enabling dark room viewing and lowering of screen brightness requirements (phosphors are used in CRTs, plasmas, and LCDs with CCF or white LED back lighting).
6. Provides a low level of illumination in the room for movement and peripheral activities.

I thought the idea of having low level lighting behind ones TV was reasonably well known?

I do think this list of benefits is funny though. Basically, viewing in the dark enhances contrast and means the screen brightness can be turned down, but can tire the eyes. However, a light in front of the screen can cause reflections so put it behind the screen. The last one is the best, a bit of light means you won't stub your toe when you get up to go to the loo :).

Jason P
02-12-2011, 18:28
I've been doing this for a while now. In my working life I edit TV programmes, and my edit suite setup at home features all grey walls (18% grey recommended IIRC) and D65 lighting. It has to be this as the colour standard for all broadcast programmes conforms to a standard - REC601 in the case of standard definition and REC709 for HD.

Many of the better TVs now feature an ISF mode (or cinema mode) that emulates this standard, and without the correct lighting you won't be seeing colours as the director intended. Ambient lighting can skew your perception noticeably, but the human eye is very good at correcting information that goes against expectations - for instance if you know someone is wearing a white shirt you perceive it as such even if it's looking rather pink, or blue, depending on the ambient light. Take a picture of said shirt with a camera incorrectly set, however, and it will soon seem wrong.

IMHO getting the correct lighting for an AV system is every bit as important as positioning speakers in your stereo - after all, you wouldn't put one in a corner and the other facing out the room and say 'that's close enough' would you? Get the lighting right, and get your display calibrated (plasma or LCD/LED) and you'll be amazed at the upgrade in picture quality...

Jason