rescale

R = rescale(A, a=0.0, b=1.0; inputmin=nothing, inputmax=nothing, stretch=false, type=nothing)

A: is either a GMTgrid, GMTimage, Matrix{AbstractArray} or a file name. In later case the file is read with a call to gmtread that automatically decides how to read it based on the file extension … not 100% safe.
rescale(A) rescales all entries of an array A to [0,1].
rescale(A,b,c) rescales all entries of A to the interval [b,c].
rescale(..., inputmin=imin) sets the lower bound imin for the input range. Input values less than imin will be replaced with imin. The default is min(A).
rescale(..., inputmax=imax) sets the lower bound imax for the input range. Input values greater than imax will be replaced with imax. The default is max(A).
rescale(..., stretch=true) automatically determines [inputmin inputmax] via a call to histogram that will (try to) find good limits for histogram stretching. The form stretch=(imin,imax) allows specifying the input limits directly.
type: Converts the scaled array to this data type. Valid options are all Unsigned types (e.g. UInt8). Default returns the same data type as A if it’s an AbstractFloat, or Flot64 if A is an integer.

Returns

A GMTgrid if A is a GMTgrid of floats, a GMTimage if A is a GMTimage and type is used or an array of Float32|64 otherwise.

This function has multiple methods: