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Yuki Kawashima, Takehiro Nagai, Yasuki Yamauchi; Uniformity perception for stimulus with luminance gradient. Journal of Vision 2014;14(15):66. doi: 10.1167/14.15.66.
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© ARVO (1962-2015); The Authors (2016-present)
What is the determinant for the uniformity perception? Evaluation of the uniformity has been regarded as important in many industrial fields. There are several factors which degrade the uniformity. In this study we focus on luminance gradient. Organic electroluminescent lighting (OLED) has recently been expected to be the novel lighting devices. As OLED is a 2-dimensional surface-emitting device, non-uniformity of an OLED panel is easily visible. It is required to find a way of assessing a uniformity of OLED panel to evaluate its uniformity based on perception. In this study we measured luminance gradients that gives the same perceptual uniformity for different spatial patterns to investigate whether the luminance patterns affect uniformity perception. A test and a reference stimulus, which mimicked an OLED panel, were simultaneously presented to a subject for 1 s. The reference stimulus was a cloud-like pattern without high frequency component. The subject selected which stimulus had less uniformity by 2AFC. Eight subjects participated in the experiments. In each pattern, the extent of the gradient was varied by staircase method. We defined the equivalent luminance gradient as the luminance gradient with 50% selectivity (PSE) using a logit model. The results showed that uniformity perception is affected by the luminance gradients, its pattern or its combination. Simple gradient patterns had less uniformity than complex ones. Moreover, patterns whose central area was brighter than its peripheral appeared to be more uniform than those with the reverse pattern.
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