What is LED Display Grayscale?

LED Video Wall Display

What is LED Display Grayscale?

Grayscale refers to the shades of a color from light to dark. It’s also known as tone or gradation. Red, green, and blue all have grayscale. LED display screens generally have 8-bit, 10-bit, 12-bit, 14-bit, 16-bit, …N-bit, etc. RGB red, green, and blue, each primary color is divided into 2^N gray levels. For example, an 8-bit RGB full-color LED display has 2^8=256 gray levels for each primary color, and can display 256 X 256 X 256 = 16,777,216 colors. The number of shades determines the richness of the colors displayed. In term of LED screens, higher grayscale levels mean more detailed and vibrant images. It can display subtle details.

Table of Contents

Grayscale Principles

Grayscale images display different brightness levels between black and white. Each pixel in the image holds a value between these shades, usually represented by 8-bit data. Therefore, there are 256 possible grayscale levels, with no color involved.

The grayscale level depends on the system’s digital-to-analog conversion (DAC) capability. LED screens typically use the following systems:

1. 8-bit system: 256 levels of brightness between black and white.
2. 10-bit system: 1,024 levels of brightness.
3. 12-bit system: 4,096 levels of brightness.
4. 14-bit system: 16,384 levels of brightness.

A higher bit system gives smoother transitions between shades, which enhances the overall picture quality and detail. So is there any way to control the grayscale of LED display?

Methods to Control LED Display Grayscale

There are two main ways to control LED grayscale.

Change the current flowing through the LED.

Typically, an LED chip can handle a continuous current of about 20mA. For most LEDs, the brightness is proportional to the current, except for red LEDs, which may saturate at higher currents.

Pulse Width Modulation (PWM).

It uses the human eye’s persistence of vision. By rapidly switching the LED on and off, the brightness is controlled by adjusting the width of the light pulses. If the frequency pulses is fast enough, the human eye perceives a stable image without flicker.

Since PWM is ideal for digital control, nearly all modern LED displays use it to manage grayscale.

LED display control systems typically consist of a main control box, scanning boards, and display control devices. The main control box takes brightness data from the computer’s graphics card and distributes it to the scanning boards. Each scanning board controls several rows of LEDs. The signals for each LED are then transmitted in series.

There are two main ways to transmit control signals:

Centralized Control on the Scanning Board: The scanning board breaks down the brightness data into on/off signals (1 for on, 0 for off) for each LED. These signals are sent row by row in pulses to the LEDs. While this method requires fewer components, it results in high data transmission. For instance, a 16-level grayscale needs 16 pulses, and a 256-level grayscale requires 256 pulses, limiting the achievable grayscale levels due to device frequency constraints.

Decentralized Control with Individual PWM for Each LED

Instead of sending simple on/off signals, the scanning board sends an 8-bit brightness value to each LED. Each LED has its own PWM controller, adjusting its brightness directly. It reduces the number of pulses required for grayscale control, needing only 4 pulses for 16-level grayscale and 8 pulses for 256-level grayscale. This decentralized method makes it easier to achieve higher grayscale levels, up to 256.

How to Identify LED Screen Brightness Levels

Shop Interior Design and Mall Led Displays

Brightness identification levels refer to the range of brightness the human eye can perceive, from the darkest black to the brightest white. While LED screens can reach grayscale levels as high as 256 or even 1024, the human eye is not sensitive enough to distinguish all these levels. Often, adjacent grayscale levels may appear identical to us, and this sensitivity varies from person to person.

For LED screens, the more brightness levels the human eye can distinguish, the better. More distinguishable brightness levels mean a broader color space and the potential for richer, more vibrant images. Typically, with over 20 detectable brightness levels, LED screen are considered of good quality.

The higher the grayscale level of the LED screen, the more colorful and vivid the display becomes. On the other hand, lower grayscale levels result in simpler, less varied colors. However, higher grayscale levels also increase costs. Once the grayscale surpasses the human eye’s ability to perceive differences, the cost-effectiveness of the screen decreases.

When you are choosing LED screen grayscale parameters , you should balance visual performance with cost. You had better select a level that matches your needs without overspending.

Conclusion:

Above, we have introduced the grayscale knowledge of LED display. If you need to display more in-depth details, please choose a low-brightness, high-grayscale LED display. As a professional LED screen manufacturer, SightLED provides a variety of high-definition, high-grayscale LED displays. If you need it, please feel free to contact us.