Theme 4. Basics of Display Screens
#40: Color Depth
LG Display has continuously expanded the expressive capability of its displays to achieve more precise and lifelike picture quality. Among the many factors that define display performance, one of the most crucial is how smoothly and naturally a screen can reproduce color gradations. The key metric used to evaluate this capability is called ‘Color Depth’.
① What is Color Depth?
Color Depth (also known as bit depth) refers to the number of distinct colors a display can produce. Each pixel is made up of three subpixels—Red (R), Green (G), and Blue (B)—and each subpixel can represent a range of brightness levels expressed in bits. The higher the bit value, the greater the number of colors the display can generate.
Bits are digital units composed of 0s and 1s, where 0 represents “off” and 1 represents “on.” A single pixel can choose between these two states, so calculations are based on binary arithmetic. Therefore, a 1-bit display can represent 2¹ = 2 colors, typically black (0) and white (1).
Color displays use three subpixels—Red (R), Green (G), and Blue (B)—to produce a variety of colors. If each subpixel is 1 bit, the total number of colors is 2³ = 8, resulting in a 3-bit color display. For example:
- R(1)G(0)B(0) represents red,
- R(1)G(1)B(0) represents yellow (red + green), and
- R(0)G(0)B(0) represents black.
In reality, each primary color is not just simply on or off. Displays can reproduce many brightness and saturation levels (gradations) for each subpixel, allowing for a much wider range of colors. For example:
- 6 bit subpixels offer 64 levels (2⁶),
- 8 bit subpixels offer 256 levels (2⁸), and
- 10 bit subpixels offer 1,024 levels (2¹⁰).
The more gradation levels available, the finer the display can represent subtle color differences, enabling richer and more lifelike image quality.
For instance, a commonly used 8-bit display allows each RGB subpixel to represent 256 levels (2⁸). Combining these yields 2⁸ × 2⁸ × 2⁸ = 16,777,216 colors, or roughly 16.7 million colors. Using the same principle, a 10-bit display can produce about 1 billion colors.
In short, a higher color depth allows for smoother tonal transitions and more natural-looking images, resulting in richer and more realistic visuals.
② Why Color Depth Matters
When color depth is low, subtle gradients—such as skies or shadows—may appear with visible steps or stripes, a phenomenon known as color banding.
Early LCD panels (typically 6-bit) often suffered from this issue. Today, 8-bit color depth has become the standard for most consumer displays and video content.
However, professional monitors and HDR (High Dynamic Range) production environments commonly adopt 10-bit or higher color depth. For instance, the Rec. 2020 standard for 4K/UHD content specifies 10-bit or 12-bit color encoding.
Higher bit depth enables smoother gradation, reduces color distortion or banding during post-processing, and ensures greater color accuracy closer to the original source.
In modern HDR technologies, color depth plays a particularly critical role.
- HDR10 uses 10-bit color per subpixel,
- Dolby Vision supports up to 12-bit, allowing displays to render between 1 billion and 68.7 billion colors.
This enables extremely fine color gradations and enhanced detail in both bright and dark scenes, delivering a vivid and lifelike viewing experience.
