Black is an interesting color when it comes to digital representations like RGB (red, green, blue). Unlike other colors, black is the absence of light rather than the presence of specific wavelengths. So how do devices like computer monitors and TVs display black using RGB? Let’s take a closer look at the technical details.
RGB Color Model
The RGB color model uses varying intensities of red, green, and blue light to create the colors we see on screens. By mixing different amounts of these three primary colors, all the colors of the visible spectrum can be represented.
RGB uses an additive color model, meaning the more of each primary color added, the lighter the color becomes. Starting from black (the absence of any color), adding equal amounts of red, green and blue makes white.
Representing Black in RGB
In the RGB model, the color black is represented by turning all three components off. So an RGB value of (0, 0, 0) renders as complete black. This means no intensities of red, green or blue.
Since black is the lack of light rather than a specific color wavelength, setting RGB values to zero produces a black pixel by emitting no light.
| Color | Red | Green | Blue |
|---|---|---|---|
| Black | 0 | 0 | 0 |
As you can see in the table, black in RGB is (0, 0, 0).
Shades of Gray in RGB
While pure black is (0, 0, 0), shades of gray can be created by setting equal, low intensities of red, green and blue. For example:
| Color | Red | Green | Blue |
|---|---|---|---|
| Dark Gray | 64 | 64 | 64 |
| Medium Gray | 128 | 128 | 128 |
| Light Gray | 192 | 192 | 192 |
Using equal RGB values while increasing the intensity equally creates darker or lighter shades of gray.
Near Black Colors in RGB
While pure black is (0, 0, 0), very dark colors can be represented in RGB by using small, non-zero values. These “near black” colors can create dark shades of other hues. Here are some examples:
| Color | Red | Green | Blue |
|---|---|---|---|
| Dark Red | 64 | 0 | 0 |
| Dark Green | 0 | 64 | 0 |
| Dark Blue | 0 | 0 | 64 |
| Dark Purple | 32 | 0 | 64 |
While not completely black, these very dark colors can appear similar to black on many screens.
The Black Point
Another important concept for understanding black in RGB is the black point. This refers to the darkest black a display can render by turning off all pixel elements.
However, most screens cannot achieve a true black point of (0, 0, 0) due to limitations in display technology. There is often some light leakage even when pixels are fully off.
So the black point represents the closest possible representation of (0, 0, 0) black on a given display. It provides a reference for calibrating other dark colors.
True Black vs. OLED/LED Screens
Many modern device screens use OLED or LED technology. Unlike older displays, OLED/LED pixels can turn completely off to achieve true black levels.
This enables OLED/LED screens to display an RGB value of (0, 0, 0) as the true absence of light. They have an ideal black point at absolute zero intensity.
Older LCD screens use always-on backlights, so cannot achieve a true black point. Even with pixels off, the backlight leaks through slightly. Their black point is often closer to an RGB value like (5, 5, 5).
Black on CRT and Plasma Displays
On legacy CRT and plasma displays, displaying black was achieved by turning off the cathode ray or plasma discharge to a pixel completely.
So these older technologies could display true black by shutting off light emission from pixels, similar to OLED/LED screens. They did not suffer from light leakage issues of LCD displays.
True Black vs. Display Black
When dealing with displays, there is an important distinction between true black and display black:
– True black – The total absence of light in an absolute sense. No wavelengths are emitted or reflected.
– Display black – The darkest color the display is capable of showing, limited by its technology. May not be true zero intensity.
So while (0, 0, 0) RGB represents true black, most displays cannot accurately reproduce absolute black due to technical constraints. Their display black will be slightly above zero intensity.
Black Level and Contrast Ratio
The black level of a display determines how dark its display black is. Black level is measured in units like candelas per square meter (cd/m2).
Lower black level values indicate displays that can render darker blacks and higher dynamic range between black and white.
Contrast ratio compares the display’s black level to its white point. Higher ratios indicate it can produce a greater variance between dark and light.
Uses of True Black
While most displays cannot render true black, there are some uses that take advantage of its total lack of light:
– Photo printing – ink with zero pigment absorption achieves true black.
– Color film photography – layers of silver halide crystals can block all light.
– OLED smartphone displays – turning off LEDs creates true black pixels.
– AMOLED screen technology – actively switching off LEDs allows true black.
So while directly viewing true black is impossible, we can capture and reproduce it indirectly using photography, printing, and select display technologies.
Black in Image File Formats
display formats store black differently than RGB hex colors:
– JPEG/PNG – store black as the number 0.
– GIF – represents black by the index color value 0.
– RAW camera files – store 12/14-bit black levels proportional to sensor values.
So when working with file formats, black is typically encoded as a minimal numeric value rather than an explicit hex code.
Black in Video Signals
Analog video signals like NTSC and PAL use voltage levels to encode black:
– 0 IRE – The lowest voltage that indicates pure black in the video signal.
– 7.5 IRE – Above black, used as blanking pedestal.
So the darkest blacks in analog video are represented by the lowest possible signal voltages, not specific colors.
Black Issues on Displays
Some common black issues can occur on digital displays:
– Black crush – Dark colors appear crushed to black due to poor dynamic range.
– Clipping – Near-black colors get rounded down to pure black.
– Backlight bleed – Light leaks through LCD black pixels cause grey blacks.
– IPS glow – Light spreads across IPS LCD black levels.
– Black smearing – Blacks blur across pixels on sample-and-hold displays.
– Black flashing – Quick black-to-color transitions show temporary black frames.
So while RGB can represent true black, real-world displays introduce impairments that affect dark color accuracy.
Black in Color Spaces
Looking beyond RGB, black is represented differently in other color spaces:
– CMYK – (0,0,0,100) signifies black by 100% key ink.
– HSL – Black is represented by hue and saturation at zero, with any lightness.
– YUV – The Y luma channel is minimal for black while chroma channels (U, V) are zero.
So the exact encoding for black varies by color space, but the core idea is minimizing light emission.
Psychology of Black
Human perception of black has psychological associations and symbolism:
– Mystery – black’s unknown nature evokes mystery.
– Emptiness – black can represent undefined voids and the absence of meaning.
– Power – black is seen as bold, powerful, and authoritative.
– Sophistication – black carries a refined, elite sensibility.
– Evil – black is often associated with death, evil, or darkness.
– Depression – excessive black can reinforce depressive feelings and mindsets.
So while black may simply mean no light, cultural meanings and mood associations go far deeper psychologically.
Black and Power Saving
On modern screens, displaying black pixels can conserve energy:
– OLED displays use less power to display black pixels since their LEDs are off.
– True black pixels do not light up the backlight on LCD screens as much.
– Phones and computers can leverage black themes and screensavers to extend battery life.
– Dark mode UI settings use more black to reduce display power draw.
So while black may seem like just another color, its ability to cut power consumption has very practical impacts on modern device battery life.
The Black History of Any Company or Technology
Discussing the history of black in relation to any relevant company or technology provides opportunities for further insights. A few examples:
– The first Apple computer displays capable of true black via LCD technology.
– Research into developing OLED TVs to surpass plasma black levels.
– Techniques for printing black on paper that absorbs nearly all light.
– Kodak’s film innovations for capturing true blacks in low light conditions.
– Samsung’s AMOLED screen development for displaying true blacks on phones.
There are countless stories around the pursuit of true black, display black, and near-black colors that provide historical context.
Conclusion
While black is simply the absence of visible light, its digital representation using RGB values involves many complexities. True black as (0,0,0) is ideal, but display technologies introduce real-world limitations on reproducing absolute darkness. Black carries cultural symbolism and enables power saving on devices. As display tech continues evolving, the rendering of digital blacks will remain an evolving challenge. The quest for the perfect black point reflects black’s mystique as both the simplest and one of the most nuanced colors.