## Description

Adjust or modify a vector of colors by “turning knobs” on one or more coordinates in (r,g,b,α) space, typically by up or down scaling them.

## Usage

 ```1 2 3``` ```adjustcolor(col, alpha.f = 1, red.f = 1, green.f = 1, blue.f = 1, offset = c(0, 0, 0, 0), transform = diag(c(red.f, green.f, blue.f, alpha.f))) ```

## Arguments

 `col` vector of colors, in any format that col2rgb() accepts `alpha.f` factor modifying the opacity alpha; typically in [0,1] `red.f, green.f, blue.f` factors modifying the “red-”, “green-” or “blue-”ness of the colors, respectively. `offset` `transform`

## Value

a color vector of the same length as `col`, effectively the result of `rgb()`.

`rgb`, `col2rgb`. For more sophisticated color constructions: `convertColor`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29``` ```## Illustrative examples : opal <- palette("default") stopifnot(identical(adjustcolor(1:8, 0.75), adjustcolor(palette(), 0.75))) cbind(palette(), adjustcolor(1:8, 0.75)) ## alpha = 1/2 * previous alpha --> opaque colors x <- palette(adjustcolor(palette(), 0.5)) sines <- outer(1:20, 1:4, function(x, y) sin(x / 20 * pi * y)) matplot(sines, type = "b", pch = 21:23, col = 2:5, bg = 2:5, main = "Using an 'opaque ('translucent') color palette") x. <- adjustcolor(x, offset = c(0.5, 0.5, 0.5, 0), # <- "more white" transform = diag(c(.7, .7, .7, 0.6))) cbind(x, x.) op <- par(bg = adjustcolor("goldenrod", offset = -rep(.4, 4)), xpd = NA) plot(0:9, 0:9, type = "n", axes = FALSE, xlab = "", ylab = "", main = "adjustcolor() -> translucent") text(1:8, labels = paste0(x,"++"), col = x., cex = 8) par(op) ## and (M <- cbind( rbind( matrix(1/3, 3, 3), 0), c(0, 0, 0, 1))) adjustcolor(x, transform = M) ## revert to previous palette: active palette(opal) ```