gainoffset function

Gain and offset of values on file

These functions can be used to get or set the gain and offset parameters used to transform values when reading them from a file. The gain and offset parameters are applied to the raw values using the formula below:

value <- value * gain + offset

The default value for gain is 1 and for offset is 0. 'gain' is sometimes referred to as 'scale'.

Note that setting gain and/or offset are intended to be used with values that are stored in a file. For a Raster* object with values in memory, assigning gain or offset values will lead to the inmediate computation of new values; in such cases it would be clearer to use Arith-methods.

gain(x)
gain(x) <- value
offs(x)
offs(x) <- value

Arguments

• x: Raster* object
• value: Single numeric value

Returns

Raster* object or numeric value(s)

Examples

r <- raster(system.file("external/test.grd", package="raster"))
gain(r)
offs(r)
r[1505:1510]
gain(r) <- 10
offs(r) <- 5
r[1505:1510]