Mitra Soma, Mazumdar Debasis, Ghosh Kuntal, Bhaumik Kamales
Center for Development of Advanced Computing, Kolkata, India.
Indian Statistical Institute, Kolkata, India.
PeerJ. 2018 Sep 25;6:e5626. doi: 10.7717/peerj.5626. eCollection 2018.
The variation between the actual and perceived lightness of a stimulus has strong dependency on its background, a phenomena commonly known as lightness induction in the literature of visual neuroscience and psychology. For instance, a gray patch may perceptually appear to be darker in a background while it looks brighter when the background is reversed. In the literature it is further reported that such variation can take place in two possible ways. In case of stimulus like the Simultaneous Brightness Contrast (SBC), the apparent lightness changes in the direction opposite to that of the background lightness, a phenomenon often referred to as lightness contrast, while in the others like neon colour spreading or checkerboard illusion it occurs opposite to that, and known as lightness assimilation. The White's illusion is a typical one which according to many, does not completely conform to any of these two processes. This paper presents the result of quantification of the perceptual strength of the White's illusion as a function of the width of the background square grating as well as the length of the gray patch. A linear filter model is further proposed to simulate the possible neurophysiological phenomena responsible for this particular visual experience. The model assumes that for the White's illusion, where the edges are strong and quite a few, i.e., the spectrum is rich in high frequency components, the inhibitory surround in the classical Difference-of-Gaussians (DoG) filter gets suppressed, and the filter essentially reduces to an adaptive scale Gaussian kernel that brings about lightness assimilation. The linear filter model with a Gaussian kernel is used to simulate the White's illusion phenomena with wide variation of spatial frequency of the background grating as well as the length of the gray patch. The appropriateness of the model is presented through simulation results, which are highly tuned to the present as well as earlier psychometric results.
刺激物实际明度与感知明度之间的差异强烈依赖于其背景，这一现象在视觉神经科学和心理学文献中通常被称为明度诱导。例如，一个灰色斑块在一种背景下在感知上可能显得更暗，而当背景反转时它看起来会更亮。文献中进一步报道，这种差异可能以两种可能的方式发生。在同时明度对比（SBC）这样的刺激情况下，表观明度朝着与背景明度相反的方向变化，这种现象通常被称为明度对比，而在其他如霓虹色扩散或棋盘错觉的情况下则相反，被称为明度同化。怀特错觉就是一个典型例子，许多人认为它并不完全符合这两个过程中的任何一个。本文给出了作为背景方形光栅宽度以及灰色斑块长度函数的怀特错觉感知强度的量化结果。还提出了一个线性滤波器模型来模拟导致这种特殊视觉体验的可能神经生理现象。该模型假设，对于怀特错觉，其边缘很强且数量众多，即频谱富含高频成分，经典的高斯差分（DoG）滤波器中的抑制性周边会受到抑制，并且该滤波器基本上简化为一个自适应尺度的高斯核，从而产生明度同化。具有高斯核的线性滤波器模型被用于模拟背景光栅空间频率以及灰色斑块长度有广泛变化的怀特错觉现象。通过模拟结果展示了该模型的适用性，这些结果与当前以及早期的心理测量结果高度吻合。
