Toward Human-Aligned Luminance Measurement for Large-Format LED Displays

TL;DR

This work addresses the gap between conventional luminance measurement and human perceptual experience for large-format direct-view LED displays. It introduces a 2D imaging luminance meter that mirrors the eye’s photopic response, entrance pupil, and foveal angular resolution ($$1/120$$ degree) to quantify perceived pixel luminance across viewing distances and angles. A perception-based luminance metric is developed, along with an optimized optical design that minimizes stray-light effects, reducing measurement error from around $$7\%$$ to $$2\%$$. The study demonstrates that perceptual luminance depends on viewing distance and angular sampling, proposing a foveal-aligned standard for pixel luminance evaluation to improve visual comfort and guide standardization for large-format LED systems.

Abstract

Direct-view LED displays are widely adopted in large-format applications due to their high luminance and reliability. However, visual comfort and accurate performance evaluation remain challenging due to the complex interaction between pixel luminance, human visual perception, and measurement artifacts. In this work, we introduce a novel 2D imaging luminance meter that replicates key optical parameters of the human eye, including entrance pupil size and angular resolution, to assess perceived pixel luminance. We report comprehensive measurements across various visual field angles and distances and establish a refined luminance metric that aligns with foveal vision standards (1/120 degree). Furthermore, a new method to quantify and mitigate stray light effects significantly improves measurement precision by reducing luminance overestimation from 7\% to 2\%. Our findings provide a foundation for optimizing LED display design for perceptual comfort and advancing standardization in pixel luminance evaluation.

Figures (9)

• Figure 1: Three stages of manufacturing the direct-viewing LED display: (a) An LED board is made from a number of discrete RGB chips; (b) An LED display box is integrated from LED boards and driver circuits; and (c) A fully assembled LED display.
• Figure 2: (a) An example of LED modules showing individual pixel units. (b) An example of luminance distribution of LED pixel units in pseudo color (measurement data obtained from Hangzhou SanTest testing laboratory).
• Figure 3: Illustration of photoreceptors on human retina. The density curves for the rods and cones on the retina demonstrate the high density of cones in the center fovea. These cones are responsible for both color vision and the highest visual acuity. Visual inspection of fine detail involves focusing light from the details onto the center fovea region. The rods are absent from the fovea area. Their density rises to a high value and spreads over a large area of the retina at a few degrees away from the fovea region. These rods contribute to human night vision, motion detection, and peripheral visions.
• Figure 4: The schematics of the proposed luminance meter, which characterizes the human eye viewing condition.
• Figure 5: Measurement setup (a) An example of a 2D imaging luminance meter, (b) experiment setup with a LED screen, and a 2D imaging luminance meter. Three experiments were carried out in this study. In the first experiment, the goal is to identify the LED screen luminance at different field of views (FOVs): The luminance distribution of each LED pixel on the screen on a 2-degree field of view was measured at different distances with a luminance meter detector (LMD) with a pixel angle resolution of 0.0011 degrees (909 PPD). The average luminance within different viewing angles was drawn as a function of viewing angle. And the pixel point luminance of the LED screen can be based on 1/60 degree (60 PPD).