It allows operations like brightness adjustment, contrast adjustment, colour balance or thresholding.
The calculations are performed on non-premultiplied colour values. If the input graphics consists of premultiplied colour values, those values are automatically converted into non-premultiplied colour values for this operation. (Note that the undoing and redoing of the premultiplication can be avoided if alpha transfer function is the identity transform and all alpha values on the source graphic are set to 1.)
feComponentTransfer(input = NA, transfers = NULL, ...)
addComponentFunction(ct, channel = c("R", "G", "B", "A"), func)
transferFunction(type = c("identity", "table", "discrete", "linear", "gamma"), tableValues = numeric(), slope = 1, intercept = 0, amplitude = 1, exponent = 1, offset = 0)filterInputs.
transfer.function objects (produced by
transferFunction). The name for each element of the
list should be one of R, G, B or A.
fe.
fe.component.transfer object, produced by
feComponentTransfer.
func will be applied to.
transfer.function object, produced by
transferFunction.
type is "table", this is a list of values which
define the lookup table.
type is "linear", the slope of the linear
function.
type is "linear", the intercept of the linear
function.
type is "gamma", the amplitude of the gamma
function.
type is "gamma", the exponent of the gamma
function.
type is "gamma", the offset of the gamma
function.
feComponentTransfer, an fe.component.transfer
object.For addComponentFunction, none.For transferFunction, a transfer.function object.
filterEffect, fe.