Color Accuracy is often taken for granted in our day-to-day lives. We figure if we flip the light switch and the light comes on, we are "good to go." This isn't necessarily the case. For instance, if you flipped the light switch and a red light came on, would that affect which shirt or blouse you were going to wear that day? Would turning on a blue light affect which sock goes with which while folding your laundry? Of course, the color of light affects any color-related tasks we perform.
Color Temperature descibes the color of light emitted by a particular light source. Each form of artificial light, whether incandescent, fluorescent, or Light Emitting Diode (LED) has its own color temperature (measured in degrees Kelvin, or "K"). The color temperature of sunlight changes dramatically during the course of the day. At sunrise and sunset, the color temperature of the sun is at 2000K. An hour later, the color temperature climbs up to 3500K. By noon, in the summertime., on a clear day, the color temperature has risen to 6500K. The question you must ask yourself is when it comes to matching colors, do you want to use the color of light you get at sunrise, or at noon?
For example:
Incandescent bulbs (2800K) emit an orangish/red color of light similar to the light seen about 1/2 hour after dawn
Warm white fluorescents (3500K) produce a yellowish/orange light which resembles the light seen about an hour after dawn
Cool white fluorescents (4100K) emit greenish/yellow light which resembles the light seen at about 2 hours after dawn
Daylight fluorescents (5000K) produce a bluish/white light which most closely resembles sunlight in the midday sky
Daylight II fluorescents (6500K) produce a greenish/blue light which supposedly mimics the sun + sky in the summer months
In order for a light source to be considered "full spectrum" or "color-balanced" it must meet or exceed the following three criteria:
1. The Color Temperature of the light source must be greater than 5000K
2. The Color Rendering Index (CRI) value for the light source must be > 90
3. The Chromaticity Values (x and y coordinates) must reside in the central white portion of the Black Body Locus (see graphic below.)
Color Rendering Index (CRI) refers to how accurately a color is perceived at a given color temperature of light. Think of the CRI value as a percentage. Sunlight, by definition, has a CRI value of 100, because it is perfect. If an artificial light source, say an incandescent light bulb, has a color temperature of 2800K, but a CRI of 100, then that means that any colored object viewed in that orange/red light source will be viewed as accurately as it can... in an orange-red light source!
Click HERE for a demonstration of both Color Temperature and Color Rendering Index (CRI)
Now, if you view an object under a 4100K light source (which tends to appear yellow/green) and the CRI is only at 61, then you can see that it would be very difficult to accurately match colors. This is why it is important to understand that if you want to accurately match colors, or if you just want the most natural, color-balanced light available, you must choose a light source that has a color temperature that is at least 5000K (sunlight at around noon), with a CRI of at least 90.
Chromaticity Values (or Lighted Appearance Values) as seen in the graphic (below) involves both an x and a y value. The closer the intersection of the x & y values are to the center of the white portion of the locus, the more accurate color rendering will be.
As you can see, when it comes to accurate color rendering and improved visual performance, NaturaLux™ Filters are your best choice for safe, natural lighting!