A definition of Dmin / Dmax

Minimum and maximum density. A term used less frequently today than in the days of film, although Dmax is often listed within the specifications of scanners to show the optical density of the darkest shadows which may be recorded. A scanner’s dynamic range is calculated by subtracting Dmin – the brightest highlights capable of being recorded – from Dmax, and for a flatbed scanner is usually between 3.6 – 4.