

digital imagery - Any imagery can be represented in \digital\ form
so that the pattern of the image brightnesses forms an array of
numeric values.  In their digital form, these brightnesses (aka,
spectral reflectance values) can then be treated as numeric values
so that they can conveniently be added, subtracted, multiplied,
divided, and in general, statistically manipulated in ways that are
difficult or impossible were the image presented in a pictorial
format.
