Glossary for Geospatial Science

mask or data mask:  A processing barrier or boundary that only allows selected data values (perhaps in a chosen range or area) to pass.  Users might choose a data mask that blocks all values outside a selected value range, eliminating all image features except those in the range they want to use in a process.  A mask is more often used to confine the effects of a process to a selected area of a raster object.  (See also: processing mask.)