gainoffset.RdThese 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) <- valueRaster* object or numeric value(s)
r <- raster(system.file("external/test.grd", package="raster"))
gain(r)
#> [1] 1
offs(r)
#> [1] 0
r[1505:1510]
#> [1] 447.7600 439.2610 435.7418 390.6812 364.3720 372.6429
gain(r) <- 10
offs(r) <- 5
r[1505:1510]
#> [1] 447.7600 439.2610 435.7418 390.6812 364.3720 372.6429