Band Math
The Band MathTM routine is a flexible image processing tool with many capabilities
not available in any other image processing system. Because each ENVI user is likely
to have unique needs, the Band Math tool allows you to define your own processing
algorithms and apply them to bands or entire files opened in ENVI. Your custom
processing may be as simple or complicated as you wish. For example, you could
simply subtract one image band from another, or execute your own custom function
written in the Interactive Data Language, IDL, the language in which ENVI itself was
written.