Version 1.9.0

• Methods for the Math, Ops, Complex and Summary group generics have
  been added for the internalImage class, as well as is.na() and mean().
  This prevents R from falling back on the character methods, which aren't
  helpful. In most cases these implementations simply call the relevant generic
  on the array version of the image; the exception is Summary, which calls a
  C++ implementation to avoid allocating memory for an R array when only a
  summary value is needed. (Reported by Martin Wilson, issue #39 and divest
  issue #6.)
• Image value range calculation and NA handling in the core C++ code has been
  improved, particularly for the 32-bit integer datatype.