Grayscale Levels of LED Display Screen

Grayscale level refers to the number of distinct brightness levels of a single primary color (red, green, and blue) on an LED display screen, ranging from its darkest to its brightest.

LED lamps only have two states: “on” (brightest) and “off” (completely black). They cannot display images; they can only display text or patterns. This is because they lack grayscale.

When LED lamps can display different levels of “brightness,” from dim to maximum, the more levels they have, the more delicate the color and light transitions they can reproduce, resulting in more realistic and natural images. This is what we call grayscale.

1. How are grayscale levels represented?

Grayscale levels are usually represented using powers of 2, where N represents the number of bits.

8-bit grayscale: This is the most common basic level. It means each primary color has 2⁸ = 256 levels of brightness (from 0 to 255).

10-bit grayscale: Each primary color has 2¹⁰ = 1024 levels.

12-bit grayscale: Each primary color has 2¹² = 4096 levels.

14-bit grayscale: Each primary color has 2¹⁴ = 16384 levels.

16-bit grayscale: Each primary color has 2¹⁶ = 65536 levels.

 

For the entire pixel (composed of three sub-pixels: red, green, and blue): Based on 8-bit grayscale, the number of colors that a pixel can combine is 256 (red) × 256 (green) × 256 (blue) = 16,777,216 colors, which is 16 million colors.

If the grayscale is increased to 16-bit, the number of colors will be a huge number (65536³), far exceeding the limit of human eye resolution, and will be mainly used in professional fields to achieve the smoothest transition.

2.Why is grayscale level so important?

Grayscale level directly determines the image quality of an LED display screen, primarily in the following aspects:

（1）Color Richness:

The higher the grayscale level, the more colors can be mixed, resulting in more vibrant, saturated, and realistic colors. Low grayscale screens appear monotonous and distorted, especially when displaying gradients in the sky or skin tones, creating a heavy “color block” effect.

（2）Image Detail and Smoothness:

High grayscale enables extremely smooth color and brightness transitions. Low grayscale screens, when displaying gradients from dark to light, exhibit contour lines or “color blocks,” a phenomenon known as “color banding” due to insufficient grayscale.

（3）Detail Representation:

High grayscale retains more detail in the dark and highlight areas of an image. Low grayscale screens may render dark details as solid black and bright details as pale white.

（4）Contrast Ratio:

While contrast ratio primarily depends on the “black level” performance of the LED chips (such as using a black mask or lower reflectivity), higher gray levels mean more and finer brightness gradations to distinguish all states between “black” and “white,” thereby visually enhancing the dynamic range and three-dimensionality of the image.

3.Refresh rate is also crucial, as it’s inseparable from grayscale levels.

Grayscale levels: Determine the number of brightness levels.

Refresh rate: Determines the number of times the image is refreshed per second (in Hz).

Achieving higher grayscale levels requires a higher refresh rate. Forcing high grayscale levels with an insufficient refresh rate can lead to the following problems:

Image flicker: The human eye may perceive rapid switching.

Scanning lines appearing in photos: When photographing the screen with a phone or camera, black scanning lines or ripples may appear.

Therefore, when choosing LED display screen products, we should choose products with a grayscale level of 12-bit or higher and a refresh rate of 1920Hz or higher to ensure a good visual experience and shooting effect.