Autrusseau Florent, Thibos Larry, Shevell Steven K
Psychology, University of Chicago, 940 E. 57th Street, Chicago, IL 60637, USA.
Vision Res. 2011 Nov;51(21-22):2282-94. doi: 10.1016/j.visres.2011.08.020. Epub 2011 Aug 31.
The first physiological process influencing visual perception is the optics of the eye. The retinal image is affected by diffraction at the pupil and several kinds of optical imperfections. A model of the eye (Thibos & Bradley, 1999), which takes account of pupil aperture, chromatic aberration and wavefront aberrations, was used to determine wavelength-dependent point-spread functions, which can be convolved with any stimulus specified by its spectral distribution of light at each point. The resulting retinal spectral distribution of light was used to determine the spatial distribution of stimulation for each cone type (S, M and L). In addition, individual differences in retinal-image quality were assessed using a statistical model (Thibos, Bradley, & Hong, 2002) for population values of Zernike coefficients, which characterize imperfections of the eye's optics. The median and relatively extreme (5th and 95th percentile) modulation transfer functions (MTFs) for the S, M and L cones were determined for equal-energy-spectrum (EES) 'white' light. The typical MTF for S cones was more similar to the MTF for L and M cones after taking wavefront aberrations into account but even with aberrations the S-cone MTF typically was below the M- or L-cone MTF by a factor of at least 10 (one log unit). More generally, the model presented here provides a technique for estimating retinal image quality for the S, M and L cones for any stimulus presented to the eye. The model is applied to some informative examples.
影响视觉感知的第一个生理过程是眼睛的光学原理。视网膜图像会受到瞳孔处的衍射以及几种光学缺陷的影响。使用一种考虑了瞳孔孔径、色差和波前像差的眼睛模型（蒂博斯和布拉德利，1999年）来确定与波长相关的点扩散函数，该函数可与由每个点的光的光谱分布指定的任何刺激进行卷积。由此得到的视网膜光光谱分布用于确定每种视锥细胞类型（S、M和L）的刺激空间分布。此外，使用一种针对泽尼克系数总体值的统计模型（蒂博斯、布拉德利和洪，2002年）来评估视网膜图像质量的个体差异，泽尼克系数表征了眼睛光学的缺陷。针对等能谱（EES）“白色”光，确定了S、M和L视锥细胞的中值以及相对极端值（第5和第95百分位数）调制传递函数（MTF）。考虑波前像差后，S视锥细胞的典型MTF与L和M视锥细胞的MTF更为相似，但即使存在像差，S视锥细胞的MTF通常也比M或L视锥细胞的MTF低至少10倍（一个对数单位）。更一般地说，这里提出的模型提供了一种技术，可用于估计呈现给眼睛任何刺激时S、M和L视锥细胞的视网膜图像质量。该模型应用于一些有参考价值的例子。
