Color: a particular tint; one, or any mixture, of the constituents into which light can be separated as in the spectrum. (Oxford) The property of wavelengths of light known as color. Different wavelengths correspond to our subjective experience of different colors. (Hockenbury, 94) Produced by a combination of the color of the light (striking) an object and the color reflectivity of that part of the object’s surface. The brain can extract this information from visual inputs. (The Brain-Francis Crick, 133)

Brightness: emitting or reflecting much light, shining; pervaded by light. (Oxford) An indication of the relative light intensity of a source or object. (NCIt) The perceived intensity of a light. (Gurney, 214) Corresponds to the “amplitude” of the light wave. The higher the amplitude, the greater the degree of brightness. (Hockenbury, 94) (Term used) for colored lights. The term ’lightness’ is used for colored pigments reflecting light. (Waldman, 197) Also referred to as ‘intensity.’ Adjective - 'bright.'

Hue: the color variable to which we assign names, such as red, blue, yellow and magenta. (Waldman, 197) The attribute of a color that allows it to be identified with a yellow, red, blue, green, or other color of the spectrum. (Gurney, 215) Editor’s note - although a different property, also commonly used for “color.”

Saturation: an attribute of color. If the saturation of two colors is different, we say the colors are different. (Waldman, 197) The ‘purity’ of the light wave. Refers to the richness of a color. A highly saturated color is vivid and rich, whereas a less saturated color is faded and washed out. Pure red, which is produced by a single wavelength, is more saturated than pink, which is produced by a combination of wavelengths. (Hockenbury, 94) Also referred to as ‘purity.’

Contrast: the ability to detect sharp boundaries (stimuli) and to detect slight changes in (brightness) at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate “visual acuity” and to detect eye disease. (MeSH) In the visual arts, the juxtaposition of different forms, colors, etc., to heighten the total effect. (Oxford)

Form: the visual aspect, especially the shape or configuration, of a thing; the shape of a body. (Oxford) The sensory discrimination of a pattern shape or outline. (MeSH)

Line: a mark that is long relative to its width; a length (straight or curved) without breadth or thickness; the trace of a moving point. (NCIt) An infinite set of points in a row, a one-dimensional space. The position of a point on a line can be specified with a single number. (Stone, 114)

Light: the natural agent which emanates from the sun, an intensely heated object, etc., and stimulates sight. Now recognized as electromagnetic radiation. (Oxford) Also referred to as 'electromagnetic radiation.'

Backlight: a light that shines on the subject from behind to separate it from the background. (Gurney, 214)

Electromagnetic Spectrum: the range of “wavelengths” or frequencies over which “electromagnetic radiation” extends. (Oxford) Encompasses all possible wavelengths of electromagnetic radiation, from relatively short wavelengths (gamma rays), to much longer wavelengths (radio waves.) ‘Visible Light’ is the range of wavelengths that are detected by the human eye, commonly in the range of 380 to 740 nanometers. Shorter wavelength radiation carries more energy per unit of time than longer wavelength radiation. The sun radiates the entire electromagnetic spectrum. (Brooker, 154)

Edgelight: light that comes from behind to illuminate the fringes of the form, separating it from the background. (Gurney, 215)

Fluorescence: the absorption of light at one wavelength and reemission at a longer wavelength, typically converting ultraviolet to visible light. (Gurney, 215) Electromagnetic radiation emitted by certain substances when they are subject to incident “radiation,” “electrons,” or other particles; the property of absorbing light of short (frequently invisible) wavelength and emitting light of longer (visible) wavelength. (Oxford) 

Incandescence: the emission of light by a heated object or body. (Oxford) The emission of visible light by an object heated to a high temperature. (Gurney, 215)

LIght Absorption: the chemical or physical process of absorbing substances, energy, light, etc. (Oxford) Retention of light by the surface and conversion to heat, rather than “reflection.” (Gurney, 214)

Luminance: the lightness or darkness of a color note in relation to a gray scale. (Gurney, 217). Also referred to as ‘value’ and ‘lightness.’

Luminescence: the ability of an object to emit light at low temperatures, as opposed to incandescence. (Gurney, 216) The property of some substances of emitting light without being heated, as in fluorescence and ‘phosphorescence.’ (Oxford)

Reflected Light: light bounced from an illuminated surface, usually into a “shadow.” (Gurney, 216) The change of direction of a light ray at the surface of a ‘medium.’ (Chapple, 202)

Refracted Light: the bending of light rays as they pass from a medium of one density into another medium of a different density. (Gurney, 217) The change of direction. (Chapple, 202)

Shade: partial or comparative darkness especially as caused by shelter from direct light or heat. (Oxford)

Shadow: a dark figure projected or cast on a surface by a body intercepting rays of light (especially from the sun), showing the approximate form of the body. (Oxford) (In painting) a hue mixed with black or otherwise darkened in value. (Gurney, 217)

Spectrum: a continuum of pure hues distributed according to their “wavelength,” as when white light is refracted through a prism. (Gurney, 217)

Moving Picture: first exhibited in Paris in 1895 by the Lumiere Brothers, who scared the audience with a visual of a moving train coming toward the screen. (Goleman, 19)

Plane: an imaginary surface formed by extension of a point through any axis or two definite points. (NICt) A flat two-dimensional space, like a football field. The position of a point in a 2-D space can be specified with two numbers. (Stone, 114)

Point: a zero-dimensional space. (Stone, 114)

Surround: extending on all sides simultaneously; encircling. (NCIt) Having to do with light level or illumination in one small area of the visual scene. (The Brain-David Hubel and Torsten Wiesel, 88)

Texture: the appearance of a substance or surface; the physical or perceived structure and composition of the constituent parts or formative elements of something. (Oxford) A measure of the variation of the intensity of a surface, quantifying properties such as smoothness, coarseness, regularity, and resiliency. The term is often used as a descriptor for the structure or organization of a tissue or organ. The three principal approaches used to describe texture are statistical, structural and spectral. (NCIt)

Volume: the amount of three dimensional space occupied by an object or the capacity of a space or container. (NCIt) The position of a point in a 3-D space can be specified with three numbers. (Stone, 114)