Color Temperature, measured in degrees Kelvin, is a characteristic of visible light radiated from a black body heated to a specific temperature. In Lighting, it refers to the amount of orange vs blue hue to the white light. "Warm" Light has a more orange hue vs. "Cool" light, which has a more bluish tint to it. This can be somewhat confusing, as the lower the color temperature, the "warmer" the light and the higher the color temperature, the "cooler" the light.
Warm Light (2000K-3000K): Typically for ambient lighting in relaxation/leisure areas like Living Rooms, Hotel Lounges, Restaurants.
Neutral Light (3500-4500K): Typical for general purpose such as Offices, Lobbies, Classrooms, and Retail
Daylight White (5000-6000K): Typical for high task high visibility needs such as Workshops, Laboratories, Kitchens, and Manufacturing
Cool White (5500-6500K): Typical for outdoor lighting such as street lights, parking lots, warehouses
Comparing Full Spectrum vs Intermittent Spectrum Light Sources
In the graphic above, the top image is the spectral color distribution of light produced by American Green Lights' PerformaLUX LED. Every wavelength within the visible spectrum of light is present and in significant strength. The Fluorescent lamp's spectral distribution is full of peaks and valleys, with dominant wavelength in the green color wavelengths, and smaller peaks in the orange, yellow, cyan and blue wavelengths, and a tiny little peak of red. As such, the green visible light dominates. When a human is engulfed in the environment, the brain will self adjust to some degree, and the perception of the green is minimal. The colors will not be vibrant, but the brain adjusts perception. But in photographs, it becomes much more apparent.
The image to the right is a single photo. Both light sources are in the same room separated by a barrier to isolate the light to the left and the right of the barrier. Notice the green tint of the walls on the left compared to the right of the barrier. Because of the lack of red wavelengths from the fluorescent, you will see the contrast between the red and black
Our eyes are used to the full spectrum lighting of sunlight to see vibrant colors and accurate colors. Under sunlight, every wavelength of light is present and in significant amounts, along the entire visible light spectrum. Therefore, every color is vibrant and true.
Full Spectrum and Skin Tone
The effect of the full spectrum light is especially apparent when viewing skin tones under artificial light. Note that under fluorescent light, the dominant green wavelength and the lack of red wavelength makes the hand look washed out and unattractive, compared to the high CRI LEDs where the skin looks healthy and full of color.
This is especially important when taking photographs, applying makeup, printing or painting, selecting and displaying fabrics and clothing, or other situations where color and visual appeal are critical.
Wavelengths (Light Waves) of Visible Light
Light as we know it is made up of waves of electromagnetic radiation that fall within a specific range of wavelengths or frequencies. Within ths narrow range of wavelengths, our eyes are able to detect and perceive visible light. Electromagnetic radiation of outside the visible spectrum includes extremely short wavelengths that make up Gamma rays, X-Rays, and UV Rays. On the opposite end of the electromagnetic spectrum includes longer wavelengths such as Infrared, Microwaves, and Radio Waves.
Artificial Light and the challenge of color accuracy
Color accuracy under artificial light is a challenge, as various methods of creating artificial light radiates different wavelengths of the light spectrum. We have worked closely with the California Lighting Technology Center at UC Davis to determine that high color rendering lighting is necessary for color critical environments such as in art studios. paint stores, clothing, textile and fabrics, hospitals, and other areas where color accuracy is needed. But not just color rendering, but full spectrum high color rendering lighting.
Color Accuracy, Full Spectrum Lighting and Color Rendering Index
Color Accuracy is the current hot topic within the lighting industry. In order for your eyes to see a specific color, that wavelength of light must be present, and reflect off of the object of the same color as the light wave. If the wavelength of light is not present, that color will not be seen accurately.
Noontime Sunlight in San Diego September 1
Color is an important aspect to lighting. Color can improve the image of a space,. Color can improve the look of your products. Color can create or change the mood of the enbvironment. Color can affect your health. Here, we explore the technical aspects of light and the ways in which light is measured and specified to get the results you desire.
The main topics discussed on this page are:
American Green Lights
Typical Color Temps
1000K: Low Pressure Sodium
2200K: High Pressure Sodium
2700K: 60W Incandescent
3000K: 200W Incandescent
3400K: Tungsten Halogen
4000K: Standard Metal Halide
4200K: Typical Office Fluorescent
5000K: Daylight White
5500K: Noontime Sunshine
5500K: Daylight Metal Halide
7500K: Overcast Sky Mid-Day
10000K: Aquarium Lighting