`desaturate.Rd`

Transform a vector of given colors to the corresponding colors with chroma reduced (by a tunable amount) in HCL space.

`desaturate(col, amount = 1, ...)`

- col
vector of R colors. Can be any of the three kinds of R colors, i.e., either a color name (an element of

`colors`

), a hexadecimal (hex) string of the form`"#rrggbb"`

or`"#rrggbbaa"`

(see`rgb`

), or an integer`i`

meaning`palette()[i]`

. Additionally,`col`

can be a formal`color-class`

object or a matrix with three named rows (or columns) containing R/G/B (0-255) values.- amount
numeric specifying the amount of desaturation where

`1`

corresponds to complete desaturation,`0`

to no desaturation, and values in between to partial desaturation.- ...
additional arguments. If

`severity`

is specified it will overrule the input argument`amount`

(for convenience).

A color object as specified in the input `col`

(hexadecimal string, RGB matrix,
or formal color class) with desaturated colors.

If input `col`

is a vector given colors are first transformed to RGB
(either using `hex2RGB`

or
`col2rgb`

) and then to HCL
(`polarLUV`

). In HCL, chroma is reduced
and then the color is transformed back to a hexadecimal
string.

If input `col`

is a matrix with three rows named `R`

, `G`

, and
`B`

(top down) they are interpreted as Red-Green-Blue values within the
range `[0-255]`

. The desaturation takes place in the HCL space as well.
Instead of an (s)RGB color vector a matrix of the same size as the input
`col`

with desaturated Red-Green-Blue values will be returned.
This can be handy to avoid too many conversions.

Similarly, `col`

can be a formal `color-class`

object, in which
case the desaturated colors are returned as a formal object of the same class as the input.

Zeileis A, Fisher JC, Hornik K, Ihaka R, McWhite CD, Murrell P, Stauffer R, Wilke CO (2020).
“colorspace: A Toolbox for Manipulating and Assessing Colors and Palettes.”
*Journal of Statistical Software*, **96**(1), 1--49. doi:10.18637/jss.v096.i01

```
## rainbow of colors and their desaturated counterparts
rainbow_hcl(12)
#> [1] "#E495A5" "#DB9D85" "#C7A76C" "#ABB065" "#86B875" "#5CBD92" "#39BEB1"
#> [8] "#4CB9CC" "#7DB0DD" "#ACA4E2" "#CD99D8" "#E093C3"
desaturate(rainbow_hcl(12))
#> [1] "#ABABAB" "#ABABAB" "#ABABAB" "#ABABAB" "#ABABAB" "#ABABAB" "#ABABAB"
#> [8] "#ABABAB" "#ABABAB" "#ABABAB" "#ABABAB" "#ABABAB"
## convenience demo function
wheel <- function(col, radius = 1, ...)
pie(rep(1, length(col)), col = col, radius = radius, ...)
## compare base and colorspace palettes
## (in color and desaturated)
par(mar = rep(0, 4), mfrow = c(2, 2))
## rainbow color wheel
wheel(rainbow_hcl(12))
wheel(rainbow(12))
wheel(desaturate(rainbow_hcl(12)))
wheel(desaturate(rainbow(12)))
## apply desaturation directly on wide RGB matrix (with R/G/B channels in rows)
RGB <- diag(3) * 255
rownames(RGB) <- c("R", "G", "B")
desaturate(RGB)
#> [,1] [,2] [,3]
#> R 127.1223 219.9281 75.94690
#> G 127.1213 219.9264 75.94625
#> B 127.1266 219.9352 75.94962
```