raster (version 2.5-8)

Gain and offset: Gain and offset of values on file

Description

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.

Usage

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

Arguments

x

Raster* object

value

Single numeric value

Value

Raster* object or numeric value(s)

Examples

# NOT RUN {
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]
# }