Do you ever hear your kids complaining about their sore eyes? Do you ever notice even your eyes start to fatigue after watching TV? What is happening is your eyes are being forced to work extra hard due to your viewing environment.
Why Screens Strain Our Eyes
Your eyes work on averages – When you look at something, eg. car headlights in the distance, a pretty landscape, or a television screen, the pupils dilate to regulate light entering your eyes. The dilation is triggered by the average light received by your lights from the entire scene—not just the single brightest point of light within that scene.
When you watch television or use the computer in a dark room, your eyes see the screen as a window of bright light in the sea of darkness which is your room. The screen is very bright compared to the room. Your eyes adjust to the average brightness across your entire field of view (which includes the room) instead of only the screen brighness.
This causes two problems – First, you’re not seeing the blacks on the screen as dark because the rest of the room is darker.
Second, and more important, your eyes rapidly fatigue. Your eyes are set in the middle between bright screen and dark room. They need to focus when comprehending the bright screen. And this is why you feel dry or watery eyes, discomfort, and even tension headaches radiating from the temple. In some cases people have been getting ocular migraines—visual disturbances or even extreme headaches from the intense eye strain.
So lighting is very important for your kids. Bias lights can help a lot. Your kids eyes are not fully developed at a young age.
How Bias Lights Relieve Strain
The key is to increase the brightness in the room without introducing problems that arise from just indiscriminately flipping all the lights on.
Let’s look at the below 3D mockup of a pretty typical living room setup.
In your typical space, you have ceiling lights, floor and table lamps—all of which are located above or, in the case of maps and accent lighting, in front of the screen at roughly the same height as the viewer’s head.
Turning on these lights while watching TV does mitigate the issue of the bright screen framed against a very dim room. However, it introduces a more problems. Lighting to the side or behind the viewer projects light onto the viewing monitor. This decreases contrast, introduces glare and haze to the image, and creates another eyestrain problem.
Bias lighting is placed behind the screen you are viewing, unlike regular lighting. This raises the surrounding light levels in your viewing area without shining light toward your eyes or toward the screen itself.
The light originates outside of the sight line of the viewer and does not reflect onto the screen, you get all the benefits of increased light in the room without the problems of glare or light shining directly from the source into your eyes.
The Bonus Benefits of Bias Lighting
It makes your TV look better
First, the additional indirect lighting provided by the bias lighting increases the contrast of the on-screen image, making your picture look better.
Refer to the optical illusion image above to see the effect made apparent. The bar that stretches across the center of the image is one constant shade of gray (RGB: 142, 142, 142) but it appears to be lighter in on the dark side of the gradient and darker on the light side of the gradient. This illusion, known as the simultaneous contrast illusion, illustrates how your eyes perceive gray to be darker and richer when seen against a lighter background (on the right side), but more washed out when seen against a dark background (on the left side). Illuminate the wall behind your screen and the same contrast illusion takes effect: the grays and blacks on your screen appear richer, and the contrast seems stronger between them and the surrounding area. This makes your blakers black without shelling for an expensive monitor
Reduc brighness
Many people adjust the values for brightness and contrast to higher levels in order to get the intensity of color and black contrast they desire. They increase the brighness to that of a headlamp!
If the environment you’re watching the screen in already helps boost the contrast and create a better looking image on the screen, then you can turn the brightness back down. Not only will your eyes thank you because the screen isn’t shining at your face like a headlamp, but you’ll extend the life of the backlight mechanism in your HDTV or monitor.
Eye fatigue reduction, better looking images, and a longer life for your monitor’s backlight? What’s not to love about bias lighting? Let’s take a look at how to set it up so you don’t have to live another day with screen-induced eyestrain and washed-out pictures.
How to easily Select and Set Up Bias Lighting
Fortunately for you, it’s really cheap to implement a perfectly functional bias lighting system.
There are very pricey ways to go about doing it (such as purchasing a Philips TV equipped with their custom color-shifting bias lighting Ambilight system) but there’s absolutely no need to incur such expenses when there are plenty of inexpensive alternatives.
First, let’s break down what makes for a good bias light and why. Then, let’s look at some economical DIY and off-the-shelf solutions.
Selecting a Bias Light
Colour temperature is important
Light bulbs have a color temperature listed using the Kelvin Color Temperature Scale. Lower numbers correspond to warmer and more red the light; the higher numbers, the cooler and more blue the light. Candle flames are 1,900K and are very warm and cast a reddish/yellow light. Standard incandescent light bulbs are ~2,800K and quite warm. “Cool White” or “Daylight” bulbs have color temperatures ranging from 5,000-6,500K.
That temperature we want is 6500K. That is the reference point used in the industry that both screen manufacturers and content creators use.
The bulbs (CFL or LED) inside your TV or monitor are calibrated to 6500K. The film and digital video is color corrected to have a 6500K white reference point. The editing suites where content is edited and worked on have 6500K bias lights. Regardless of whether you use a fluorescent tube light, a strip of LEDs, or an incandescent light bulb, you want one with as close to a 6500K color temperature as you can get if your goal is to maximize the quality of the on-screen image.
This immediately rules out the majority of lighting we use around our homes, as there is a distinct consumer preference for warmer light. What makes for a homey and warm feeling in your abode makes for a poor bias light.
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