By detecting the change in this speckle, it is possible to chart the texture of the surface.
British Dictionary definitions for speckle
speckle
/ˈspɛkəl/
noun
1.
a small or slight mark usually of a contrasting colour, as on the skin, a bird's plumage, or eggs
verb
2.
(transitive) to mark with or as if with speckles
Derived Forms
speckled, adjective
Word Origin
C15: from Middle Dutch spekkel; see speck
Word Origin and History for speckle
v.
c.1400 (implied in speckled), probably related to Old English specca "small spot, speck" (see speck) or from a related Middle Dutch or Middle High German word. Related: Speckled; speckling. The noun is first attested mid-15c.