How TCL’s XRGB Achieves BT.2020 131% Color Gamut with a Four‑Color Pixel Architecture

Problem

Human vision can perceive colors beyond the gamut achievable with the conventional three‑color (RGB) pixel architecture. The cyan band around 495 nm, common in water, sky, and vegetation, is reproduced only by mixing green and blue, leading to color‑accuracy loss and detail loss in that spectral region.

Pixel Architecture Redesign

TCL Huaxing introduced an independent cyan sub‑pixel, creating an RGBC four‑color layout. The redesign involved:

Precise geometric reconstruction of pixel shape.

Systematic optimization of sub‑pixel spacing, area ratio, and optical crosstalk.

Maintaining overall pixel density comparable to standard RGB panels.

This restructuring balances energy efficiency with picture‑quality goals.

Cyan Filter and Backlight

A proprietary cyan color‑filter (C) was developed from an in‑house material library, providing high transmission for the cyan wavelength. To supply the correct cyan spectrum, a dedicated RGBC LED backlight (BLU) module emitting pure cyan at approximately 490‑500 nm was integrated, enabling the BT.2020 131 % color‑gamut target.

Color Mapping Algorithm

Existing RGB‑encoded content must be rendered on the four‑color panel. The RGBC color‑mapping algorithm proceeds in three steps:

Parse the input signal into the CIE‑XYZ color space to build a three‑dimensional color‑mapping model.

Decompose the XYZ coordinates into four independent drive components (R, G, B, C) according to spectral optimality, maximizing the cyan sub‑pixel contribution.

Apply per‑channel gamma calibration to ensure linear grayscale consistency across 256 levels for all four channels, eliminating color shift and banding.

The algorithm allows 4K HDR video, games, and photos to be displayed without changing the source content.

Key Specifications

Color gamut (BT.2020): 131 %

Native contrast: 7000:1

Reflectivity (LR): 0.7 %

Resolution: 3840×2160 (true 4K+)

Color architecture: RGBC four‑color

Demonstration

The full‑system display was showcased at the SID2026 exhibition, demonstrating the BT.2020 131 % gamut, high contrast, and low reflectivity.