US Army, CCDC Army Research Laboratory, Human Research and Engineering Directorate, United States.
US Army, CCDC Army Research Laboratory, Human Research and Engineering Directorate, United States.
J Neurosci Methods. 2020 May 15;338:108684. doi: 10.1016/j.jneumeth.2020.108684. Epub 2020 Mar 10.
Real-world illumination challenges both autonomous sensing and displays, because scene luminance can vary by up to 10-to-1, whereas vision models have limited ability to generalize beyond 100-to-1 luminance contrast. Brain mechanisms automatically normalize the visual input based on feature context, but they remain poorly understood because of the limitations of commercially available displays.
Here, we describe procedures for setup, calibration, and precision check of an HDR display system, based on a JVC DLA-RS600U reference projector, with over 100,000-to-1 luminance dynamic range (636-0.006055 cd/m), pseudo 11 bit grayscale precision, and 3 ms temporal precision in the MATLAB/Psychtoolbox software environment. The setup is synchronized with electroencephalography (EEG) and infrared eye-tracking measurements.
We show display metrics including light scatter versus average display luminance (ADL), spatial uniformity, and spatial uniformity at high spatial frequency. We also show a luminance normalization phenomenon, contextual facilitation of a high contrast target, whose discovery required HDR display.
This system provides 100-fold greater dynamic range than standard 1000-to-1 contrast displays and increases the number of gray levels from 256 or 1024 (8 or 10 bits) to 2048 (pseudo 11 bits), enabling the study of mesopic-to-photopic vision, at the expense of spatial non-uniformities.
This HDR research capability opens new questions of how visual perception is resilient to real-world luminance dynamics and will lead to improved visual modeling of dense urban and forest environments and of mixed indoor-outdoor environments such as cockpits and augmented reality. Our display metrics code can be found at https://github.com/USArmyResearchLab/ARL-Display-Metrics-and-Average-Display-Luminance.
真实世界的光照条件给自主感知和显示带来了挑战，因为场景亮度的变化范围可达 10 比 1，而视觉模型的泛化能力在 100 比 1 的亮度对比度之外非常有限。大脑机制会根据特征上下文自动对视觉输入进行归一化，但由于商业上可用的显示器的限制，这些机制仍然知之甚少。
在这里，我们描述了基于 JVC DLA-RS600U 参考投影仪的 HDR 显示系统的设置、校准和精度检查程序，该投影仪的亮度动态范围超过 100,000 比 1（636-0.006055cd/m），具有伪 11 位灰度精度，以及在 MATLAB/Psychtoolbox 软件环境中的 3ms 时间精度。该设置与脑电图 (EEG) 和红外眼动跟踪测量同步。
我们展示了包括光散射与平均显示亮度 (ADL)、空间均匀性和高频空间均匀性在内的显示指标。我们还展示了一种亮度归一化现象，即高对比度目标的上下文促进，这一现象的发现需要 HDR 显示。
与标准的 1000 比 1 对比度显示器相比，该系统提供了 100 倍的动态范围，并将灰度级从 256 或 1024（8 位或 10 位）增加到 2048（伪 11 位），从而能够研究中值到光值视觉，但其代价是空间不均匀性。
这种 HDR 研究能力提出了新的问题，即视觉感知如何对真实世界的亮度动态具有弹性，并将导致对密集城市和森林环境以及混合室内外环境（如驾驶舱和增强现实）的视觉建模的改进。我们的显示指标代码可在 https://github.com/USArmyResearchLab/ARL-Display-Metrics-and-Average-Display-Luminance 找到。
