Colors, shadows and light
Visual space and its control -The visual environment

The appearance of a surface is characterized by a large number of parameters. The most important are undoubtedly its color, its ability to reflect light diffusely or specularly, and its grain size. If it's an object, the visual system's means of identification will be completed by its shapes, shadows and the particular experience we have of it.

These properties are not independent of each other: for example, the grain size will influence the surface's ability to scatter light; hue and lightness, which are linked to the reflection factor (although painters prefer to talk in terms of value), are interdependent, as shown in figures 2 and 3...