Vision and Art: The Biology of Seeing (Margaret Livingstone, 2008), is one of the books we’re planning to bring up at this afternoon’s Critique and Conversation. Alisha, who chose it, has picked out this quote and added a line of commentary underneath —
Luminance or what artists refer to as value, is perceived lightness. Luminance is not a physical measurement, and the luminance of any particular number of photons varies depending on the wavelength of that light it is determined by how sensitive our eyes are to that color of light. Understanding luminance is important because our perception of depth, three-dimensionality, movement (or the lack of it) and spatial organization are all carried by a part of our visual system that responds only to luminance differences and is insensitive to color.
The black-and white version of David Ryan’s LHC (2008) shows the painting’s lightness (luminance) values and reveals how much information is carried by luminance alone.