Sinusoidal luminance patterns appear dramatically saturated toward the brighter regions. The saturation is not perceptually logarithmic but exhibits a hyperbolic (Naka–Rushton) compression behavior at normal indoor luminance levels. The object interpretation of the spoke patterns is not consistent with the default assumption of any unidirectional light source but implies a diffuse illumination source (as if the object were looming out of a fog). The depth interpretation is, however, consistent with the hypothesis that the compressed brightness profile provided the neural signal for perceived shape, as an approximation to computing the diffuse Lambertian illumination function for this surface. The surface material of the images is perceived as non-Lambertian to varying degrees, ranging from a chalky matte to a lustrous metallic.