Hung Chou P, Callahan-Flintoft Chloe, Fedele Paul D, Fluitt Kim F, Odoemene Onyekachi, Walker Anthony J, Harrison Andre V, Vaughan Barry D, Jaswa Matthew S, Wei Min
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J Vis. 2020 Jul 1;20(7):9. doi: 10.1167/jov.20.7.9.
When scanning across a scene, luminance can vary by up to 100,000-to-1 (high dynamic range, HDR), requiring multiple normalizing mechanisms spanning from the retina to the cortex to support visual acuity and recognition. Vision models based on standard dynamic range (SDR) luminance contrast ratios below 100-to-1 have limited ability to generalize to real-world scenes with HDR luminance. To characterize how orientation and luminance are linked in brain mechanisms for luminance normalization, we measured orientation discrimination of Gabor targets under HDR luminance dynamics. We report a novel phenomenon, that abrupt 10- to 100-fold darkening engages contextual facilitation, distorting the apparent orientation of a high-contrast central target. Surprisingly, facilitation was influenced by grouping by luminance similarity, as well as by the degree of luminance variability in the surround. These results challenge vision models based solely on activity normalization and raise new questions that will lead to models that perform better in real-world scenes.
当扫视一个场景时，亮度变化可达100000比1（高动态范围，HDR），这需要从视网膜到皮层的多种归一化机制来支持视敏度和识别。基于低于100比1的标准动态范围（SDR）亮度对比度的视觉模型，推广到具有HDR亮度的真实世界场景的能力有限。为了表征在用于亮度归一化的大脑机制中方向和亮度是如何联系的，我们在HDR亮度动态下测量了Gabor目标的方向辨别。我们报告了一个新现象，即突然10到100倍的变暗会引发背景促进作用，扭曲高对比度中央目标的表观方向。令人惊讶的是，促进作用受到亮度相似性分组以及周围亮度变化程度的影响。这些结果挑战了仅基于活动归一化的视觉模型，并提出了新问题，这些问题将催生在真实世界场景中表现更好的模型。
