White is a color that can be made by combining red, green, and blue (RGB) light. The specific combination needed to make white depends on whether you are working with additive or subtractive color mixing.
Additive Color Mixing
With additive color mixing, white is made by combining red, green, and blue light at full intensity. This is how computer and TV screens make white – by lighting up all the red, green, and blue subpixels to their maximum brightness.
The red, green, and blue components can each be described with 8 bits, allowing integer brightness values from 0 to 255. To make pure white on a computer monitor using additive RGB:
- Red intensity = 255
- Green intensity = 255
- Blue intensity = 255
This can be written in hexadecimal as #FFFFFF. When added together, the maximum intensity of red, green, and blue light appears as white.
Subtractive Color Mixing
With subtractive color mixing, white is made by absorbing no color. This is how paints and inks make white – by not absorbing any wavelengths of visible light. All wavelengths are reflected back to the eye, creating the appearance of white.
The absorbance or reflectance of red, green, and blue can each be described from 0% to 100%. For subtractive color mixing:
- Red absorbance = 0%
- Green absorbance = 0%
- Blue absorbance = 0%
With no colors absorbed, white is the result. This is equivalent to:
- Red reflectance = 100%
- Green reflectance = 100%
- Blue reflectance = 100%
When red, green, and blue light is fully reflected back to the eye, white is perceived.
Examples
Here are some examples of how to make white RGB colors for different applications:
| Application | Red | Green | Blue |
|---|---|---|---|
| Computer monitor | 255 | 255 | 255 |
| TV display | 255 | 255 | 255 |
| Web colors | #FF | #FF | #FF |
| Paint | 100% reflectance | 100% reflectance | 100% reflectance |
| Ink | 0% absorbance | 0% absorbance | 0% absorbance |
As shown, for additive color systems you want the maximum red, green, and blue values. For subtractive systems, you want no absorbance/full reflectance of red, green, and blue.
True White vs Off White
The examples above all produce a “true” white by mixing fully saturated red, green, and blue. You can also make “off whites” by lowering the intensities.
For example, an RGB value of (250, 250, 250) would appear as an off white with a slight gray tint. Values like (240, 248, 255) can give different white tones.
Pure white light contains equal intensities of all visible wavelengths. Deviating from full red, green, and blue mixes produces various shades of white.
Shades of White
There are many shades of white that have common names. These originate from different mixes of RGB components. Some examples include:
- Ivory – Slightly yellowish white
- Cream – Soft warm white
- Pearl – Cool light grayish white
- Snow – Crisp clean white
- Linen – Natural muted white
Different ratios of red, green, and blue can produce these shades. For instance, ivory has more red, pearl has more blue, and so on. Adjusting the RGB balance allows almost any white hue to be created.
White Balance
When mixing light sources, the overall “white point” can vary. Computer monitors, TVs, light bulbs, and daylight all produce white at different color temperatures.
White balance controls adjust RGB levels to set the white point and correct for ambient lighting conditions. This ensures whites appear consistent across different environments.
Non-RGB White Light
While red, green, and blue are the primary colors for screens, other light sources can produce white in different ways. Some examples include:
- Incandescent bulbs – Mixing wavelengths from heated filament
- Fluorescent lighting – Ultraviolet generating photophosphors
- LED bulbs – Combining blue LED with yellow phosphor
- Sunlight – Full spectrum emission from sun
These sources appear white due to emitting a broad spectrum of wavelengths, or blending complementary colors.
Additive vs Subtractive Summary
In summary, there are two primary ways to make white:
- Additive white – Mixing red, green, and blue light at maximum intensities
- Subtractive white – Absorbing no red, green, and blue wavelengths
Additive mixing is for light emission, such as displays. Subtractive is for surface reflection, like paint and ink.
True white occurs when there is uniform intensity or reflectance across visible wavelengths. Off whites can be made by adjusting RGB components.
Conclusion
White is made by blending red, green, and blue colors of light. For additive mixing, this means combining fully saturated RGB components. For subtractive mixing, it involves none of the components being absorbed.
The specific RGB values required depends on the medium. But in general, white is produced when there is equal intensity or reflectance of all visible wavelengths of light.
Pure white light can be desaturated to create off whites and tinted shades. Overall, a balanced RGB mix allows great flexibility in producing any desired white color.
