LED display specifications explained

7.1 Pixel pitch

Smaller pitch places more pixels in the same physical area and usually supports a closer viewing distance. It also increases the number of components, data channels and manufacturing operations for a display of a given size, which affects cost and complexity.

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Figure 4. Pixel pitch and pixel density.

There is no universal formula that converts pitch into a guaranteed viewing distance. Minimum acceptable distance depends on content, eyesight, application, pixel shape, fill factor, surface treatment, contrast and tolerance for visible structure. A mock-up viewed with representative content is more reliable than a single rule of thumb.

7.2 Resolution and physical size

Resolution is the number of addressable pixels horizontally and vertically. In a modular LED display, it depends on both physical dimensions and pixel pitch.

The approximate relationship is:

Horizontal pixels = display width in millimetres / pixel pitch in millimetres

Vertical pixels = display height in millimetres / pixel pitch in millimetres

For a 1,920-pixel-wide image:

A large display is not automatically high resolution. A physically smaller fine-pitch display can contain more pixels than a much larger stadium screen.

7.3 Aspect ratio and canvas shape

Aspect ratio is the relationship between width and height. Common video is 16:9, but LED systems can be ultra-wide, portrait, square, curved or irregular. Non-standard canvases are useful, but they require deliberate content design. Simply stretching 16:9 material across an unusual shape can distort imagery or leave unused areas.

The actual pixel canvas should be documented as width by height in pixels, not only metres. That pixel map becomes the basis for content templates, source routing and testing.

7.4 Luminance and the nit

Display brightness is more accurately described as luminance and is commonly expressed in candelas per square metre, written cd/m2. The informal unit "nit" is numerically equivalent to 1 cd/m2. The National Institute of Standards and Technology's explanation of the candela provides the SI context.

Outdoor displays need sufficient luminance to overcome daylight, but maximum output is not the same as correct operating output. Excessive luminance can reduce comfort, increase power use and make black levels appear raised. Automatic or scheduled control can help match output to ambient conditions, provided the control strategy is commissioned and governed appropriately.

7.5 Contrast and black level

Contrast is the relationship between bright and dark output. Laboratory contrast figures may be measured in a dark environment, while real installations contain ambient light reflected from the display surface. For many indoor applications, surface reflectance and black appearance under room lighting are as important as peak luminance.

A display can achieve a strong dark-room ratio yet look grey in a bright space. Samples should therefore be assessed under lighting that represents the final site.

7.6 Colour gamut and colour space

A colour gamut describes the range of colours a system can reproduce. Common video references include ITU-R BT.709 for HDTV and the wider BT.2020 colour primaries for ultra-high-definition systems. The official ITU-R BT.709 recommendation and BT.2020 recommendation define more than primaries alone; they are parts of broader television systems.

A statement such as "140% Rec.709" is incomplete unless the measurement method and colour-volume interpretation are clear. More gamut is not always more accurate. The objective is to reproduce the intended colour space predictably, not to make every colour as saturated as possible.

7.7 White point and colour temperature

The white point defines the chromaticity treated as neutral white. Video workflows commonly target a D65-related white point, but perceived white is influenced by ambient light and surrounding surfaces. Displays used together must be matched to the same target and evaluated from relevant viewing positions.

Colour temperature controls labelled with kelvin values are useful only if the system is measured. A menu value is not proof of the emitted chromaticity.

7.8 Bit depth and greyscale

Bit depth describes the number of digital code values available for each colour channel. Higher internal precision can support smoother gradients and better low-level control, but the complete chain matters: source encoding, processor precision, driver architecture, calibration and noise all influence the visible result.

Marketing sometimes multiplies channel values into extremely large colour counts. Those numbers do not by themselves show whether a display can render clean dark gradients without banding, colour shifts or crushed detail. Low-grey test material is more revealing.

7.9 Refresh rate, frame rate and scan rate

These terms are related but different:

• Frame rate is the rate at which source images are presented, such as 25, 50 or 60 frames per second.

• Refresh rate is the rate at which the display updates or repeats pixel information.

• Scan ratio describes multiplexing, where groups of rows are driven in sequence rather than continuously.

• PWM frequency and behaviour influence how brightness is modulated.

A high refresh-rate number is valuable for camera use and visual stability, but it is not a complete camera-performance specification. Shutter angle, frame rate, genlock, scan pattern, brightness level, processor timing and panel design interact.

7.10 Viewing angle

Viewing angle describes the range over which luminance, colour and contrast remain acceptable. Published figures often use a threshold such as half-brightness, which may not correspond to the point at which colour shift becomes objectionable.

For a wide audience, evaluate both horizontal and vertical behaviour. Vertical viewing can be especially important when a display is mounted high or when floors and balconies create steep sightlines.

7.11 IP rating

An IP code classifies protection provided by an enclosure against access, solid foreign objects and water. The authoritative framework is IEC 60529; the IEC publication page and BSI's current standard listing describe the standard.

An IP code must be read digit by digit and applies to the tested enclosure arrangement. It does not automatically prove resistance to salt, ultraviolet exposure, condensation, pollution, wind-driven water, cleaning chemicals or poorly sealed site interfaces. Front and rear ratings may differ.

7.12 Power figures

Manufacturers may publish maximum, average or typical power per square metre. Compare like with like and ask:

• At what luminance and test image was the figure measured?

• Does it include all processing and cooling equipment?

• Is it input power at a stated voltage?

• What diversity assumption is acceptable for electrical design?

• How does automatic brightness control affect expected annual energy use?

Electrical infrastructure must be designed for the relevant maximum demand and local requirements, even when expected average consumption is lower.

7.13 Latency

Latency is the time between source input and visible output. It matters in live image magnification, broadcast, virtual production, interactive work and control rooms. The total includes source capture, switching, scaling, transport, display processing and scan-out.

A quoted panel latency is therefore only one part of the end-to-end path. Measure the complete system in its intended operating mode when timing is critical.

7.14 Lifetime and reliability claims

LED lifetime is often expressed as the time to a defined reduction in light output, sometimes called L70 or L50 in lighting contexts. Display manufacturers may publish figures such as 50,000 or 100,000 hours, but methods and criteria vary.

The complete screen includes parts with different ageing modes: LEDs, driver ICs, power supplies, fans, connectors, coatings, seals, circuit boards and mechanical structures. Temperature, luminance, environment, operating hours and content all affect stress. A headline lifetime should therefore be treated as a test claim, not a guaranteed date at which the complete display will fail or remain uniform.

7.15 Uniformity and calibration

Uniformity describes consistency of luminance and colour across pixels, modules and cabinets. Manufacturing binning reduces variation, while calibration systems can store correction values. Calibration is conceptually important but is not a permanent cure for physical ageing, contamination, optical damage or incompatible replacement parts.

The strongest evaluation uses flat fields, dark greys, gradients, skin tones and representative content at several luminance levels and viewing angles.