Color Accuracy
Colors matter !
Despite decades of using LED screens to display meticulously crafted content, recent years have revealed a startling truth: most displays fail to reproduce colors accurately.
The Camera's Critical Eye
The surge in virtual production studios, where LED screens serve as backdrops, has intensified the demand for color accuracy. These displays must not only faithfully reproduce content colors but also, crucially, render them linearly. This linearity ensures simple and predictable color adjustments can be done on set to match the camera sensor's unique response.
The Importance of Color Accuracy
In early 2023, the Entertainment Technology Centre (ETC) at the University of Southern California conducted a comprehensive study on LED screen performance in the entertainment industry. Their findings highlighted color accuracy as the most critical factor in evaluating LED displays. The ETC rigorously tested around 15 panels from various manufacturers, publishing anonymized performance reports alongside detailed testing guidelines and methodology.
White Point Accuracy: The Foundation of Color Fidelity
Maintaining an accurate D65 white point across the entire brightness range is fundamental to achieving precise color reproduction on a display.
D65 white is defined by two parameters:
Color Temperature (˚K): This indicates whether the white appears too warm (reddish) or too cold (bluish).
∆uv: This value, orthogonal to color temperature, measures any deviation towards pink or green.
For optimal color accuracy, the displayed D65 white point should maintain consistent color temperature and ∆uv values at all brightness levels.
A hallmark of high-quality displays is a stable D65 white point. This means maintaining consistent color temperature and ∆uv values throughout the entire brightness range.
Evaluating Color Accuracy
Once the white point accuracy is established, the next crucial step is assessing a display's ability to faithfully reproduce a wide spectrum of colors. This involves displaying and measuring hundreds of color points at various brightness levels, then calculating the error for each displayed color.
To gain deeper insights, color error can be broken down into its constituent parts: brightness error and color error. The Entertainment Technology Center (ETC) chose to compute and report color error using the ICtCp color space, a sophisticated color space well-suited for HDR displays.
A color error of 1 Just Noticeable Difference (JND) in ICtCp indicates a color difference that is just barely noticeable, while an error of 2 JNDs would be slightly more noticeable but still relatively subtle. An error above 4JNDs is readily apparent.
Performance synthesis of a
Standard panel from the ETC report
Standard panel from the ETC report
While a typical LED display may exhibit acceptable color accuracy at its maximum brightness for the D65 white point, this performance often deteriorates significantly as brightness decreases below 200 nits. Consequently, the overall color accuracy of such displays remains subpar.
Performance synthesis of a
Panel with Deepsky components Inside
Panel with Deepsky components Inside
This display delivers remarkably consistent and accurate color reproduction across its entire brightness range. The D65 white point remains precisely calibrated at all levels. This level of color fidelity makes it a valuable tool for applications where color accuracy is paramount.
Performance synthesis of the
Best panel from the ETC 2023 report
Best panel from the ETC 2023 report
The top-performing panel tested in 2023 maintains excellent D65 white point accuracy across its entire brightness range. While its brightness errors for colors generally stay below 2 JND (Just Noticeable Difference), it exhibits noticeable chromatic errors.
Performance synthesis of a
panel with Deepsky components Inside
panel with Deepsky components Inside
Deepsky-powered LED displays deliver significantly improved color accuracy. Brightness errors for color points are consistently below 1 JND, making them virtually imperceptible. Chromatic errors remain impressively low, typically below 2 JND, ensuring a color-accurate experience.
Key metrics
The overall color accuracy of a display panel can be effectively summarized using two key metrics:
Average Error: Represents the typical deviation from the intended color across all measured points.
Maximum Error (95th Percentile): Highlights the worst-case color accuracy by focusing on the 5th worst displayed error (as used by the ETC).
In both cases, lower error values indicate superior color performance.
