面向三角靶标的人眼对比度阈值特性实验表征

人眼视觉对比度阈值特性是光电成像系统性能建模的重要基础，面向三角靶标的人眼对比度阈值特性是三角方向鉴别阈值性能模型构建的前提．以人眼鉴别三角靶标方位的强制四选一度量思想为基础，搭建了集靶标生成、显示控制和测量分析于一体的综合测试平台; 通过设置不同背景光亮度，统计了7种不同空间频率的三角形靶标方向鉴别概率; 采用韦布尔视觉心理测量函数分析测量数据，获得75％正确判别概率对应的人眼对比度阈值曲线．在正常观察亮度范围内，测量结果分析表明: 当背景亮度相同时，三角形空间频率越大，人眼正确判别所需要的对比度阈值越高; 当空间频率相同时，三角形背景亮度越大，人眼正确判别所需要的对比度阈值越小．

Experimental characterization of the human vision contrast threshold for the triangle pattern

The human vision contrast threshold characteristic is an important basis for the performance evaluation of the Electro-Optical (EO) imaging system. The Human vision contrast threshold characteristic for the triangle pattern is the premise for constructing the performance model based on the triangle orientation discrimination threshold. In this paper, a comprehensive test platform which integrates pattern generation, display control, measurement and analysis is constructed based on the 4AFC methodology used in the triangle orientation discrimination The discrimination probabilities of the triangle pattern with seven different spatial frequencies are measured at different background luminance levels. Futher, the Weibull function is fitted to the experiment data, and the curves of the human visual contrast threshold vs. the 75％ correct discrimination probability are obtained. In the normal viewing luminance range, the results show that the contrast threshold increases with the increase of the target spatial frequency for the same background luminance, and the contrast threshold decreases with the increase of the background luminance for the same target spatial frequency.