R: Perform Colour Component-wise Remapping.

feComponentTransfer {gridSVG} | R Documentation

## Perform Colour Component-wise Remapping.

### Description

This filter primitive performs component-wise remapping of data by taking a colour transfer function, and applying that to the set of RGBA colour components.

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.)

### Usage

    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)

### Arguments

`input` | Identifies an input for this filter primtive. See `filterInputs`.
`transfers` | A named list of `transfer.function` objects (produced by `transferFunction`). The name for each element of the list should be one of `R`, `G`, `B` or `A`.
`...` | Further arguments to be passed onto `fe`.
`ct` | An `fe.component.transfer` object, produced by `feComponentTransfer`.
`channel` | The colour channel that `func` will be applied to.
`func` | A `transfer.function` object, produced by `transferFunction`.
`type` | Indicates the type of component transfer function. The type of function determines the applicability of the other arguments.
`tableValues` | When `type` is `"table"`, this is a list of values which define the lookup table.
`slope` | When `type` is `"linear"`, the slope of the linear function.
`intercept` | When `type` is `"linear"`, the intercept of the linear function.
`amplitude` | When `type` is `"gamma"`, the amplitude of the gamma function.
`exponent` | When `type` is `"gamma"`, the exponent of the gamma function.
`offset` | When `type` is `"gamma"`, the offset of the gamma function.

### Details

For more information about this primitive, consult the references to the SVG specification.

### Value

For `feComponentTransfer`, an `fe.component.transfer` object.

For `addComponentFunction`, none.

For `transferFunction`, a `transfer.function` object.

### Author(s)

Simon Potter

### References

http://www.w3.org/TR/SVG/filters.html#feComponentTransferElement, http://www.w3.org/TR/SVG/filters.html#feFuncRElement

### See Also

`filterEffect`, `fe`.

[Package gridSVG version 1.6-0 Index]