lighten {colorspace} | R Documentation |
Algorithmically Lighten or Darken Colors
Description
The functions lighten
and darken
take a vector of R colors and adjust the colors such that
they appear lightened or darkened, respectively.
Usage
lighten(
col,
amount = 0.1,
method = c("relative", "absolute"),
space = c("HCL", "HLS", "combined"),
fixup = TRUE
)
darken(col, amount = 0.1, space = "combined", ...)
Arguments
col |
vector of any of the three kind of R colors, i.e., either a color
name (an element of |
amount |
numeric specifying the amount of lightening. This is applied either
multiplicatively or additively to the luminance value, depending on the
setting of |
method |
character string specifying the adjustment method. Can be either |
space |
character string specifying the color space in which adjustment happens. Can be either |
fixup |
logical If set to |
... |
Other parameters handed to the function |
Details
The color adjustment can be calculated in three different color spaces.
If
space = "HCL"
, the colors are transformed to HCL, (polarLUV
), the luminance component L is adjusted, and then the colors are transformed back to a hexadecimal RGB string.If
space = "HLS"
, the colors are transformed to HLS, the lightness component L is adjusted, and then the color is transformed back to a hexadecimal RGB string.If
space = "combined"
, the colors are first adjusted in both the HCL and HLS spaces. Then, the adjusted HLS colors are converted into HCL, and then the chroma components of the adjusted HLS colors are copied to the adjusted HCL colors. Thus, in effect, the combined model adjusts luminance in HCL space but chroma in HLS space.
We have found that typically space = "HCL"
performs best for lightening colors and space = "combined"
performs best for darkening colors, and these are the default settings for lighten
and darken
,
respectively.
Regardless of the chosen color space, the adjustment of the L component can occur by two methods, relative
(the default) and absolute. Under the absolute method, the adjustment is L +/- 100 * amount
when
lightening/darkening colors. Under the relative method, the adjustment is 100 - (100 - L) * (1 - amount)
when
lightening colors and L * (1 - amount)
when darkening colors.
Programmatically lightening and darkening colors can yield unexpected results (see examples). In HCL space,
colors can become either too gray or overly colorful. By contrast, in HLS space it can happen that the
overall amount of lightening or darkening appears to be non-uniform among a group of colors that are
lightened or darkened jointly, and again, colors can become either too gray or overly colorful. We
recommend to try different color spaces if the default space for the chosen function (lighten
or darken
) does not look right in a specific application.
Value
A character vector with (s)RGB codings of the colors in the palette.
References
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
See Also
Examples
# lighten dark colors, example 1
cl <- qualitative_hcl(5)
swatchplot(list(
HCL = rbind("0%" = cl,
"15%" = lighten(cl, 0.15),
"30%" = lighten(cl, 0.3)),
HLS = rbind("0%" = cl,
"15%" = lighten(cl, 0.15, space = "HLS"),
"30%" = lighten(cl, 0.3, space = "HLS")),
combined = rbind("0%" = cl,
"15%" = lighten(cl, 0.15, space = "combined"),
"30%" = lighten(cl, 0.3, space = "combined"))),
nrow = 4, line = 2.5
)
# lighten dark colors, example 2
cl <- c("#61A9D9", "#ADD668", "#E6D152", "#CE6BAF", "#797CBA")
swatchplot(list(
HCL = rbind("0%" = cl,
"15%" = lighten(cl, 0.15),
"30%" = lighten(cl, 0.3)),
HLS = rbind("0%" = cl,
"15%" = lighten(cl, 0.15, space = "HLS"),
"30%" = lighten(cl, 0.3, space = "HLS")),
combined = rbind("0%" = cl,
"15%" = lighten(cl, 0.15, space = "combined"),
"30%" = lighten(cl, 0.3, space = "combined"))),
nrow = 4, line = 2.5
)
# darken light colors, example 1
cl <- qualitative_hcl(5, "Pastel 1")
swatchplot(list(
combined = rbind("0%" = cl,
"15%" = darken(cl, 0.15),
"30%" = darken(cl, 0.3)),
HCL = rbind("0%" = cl,
"15%" = darken(cl, 0.15, space = "HCL"),
"30%" = darken(cl, 0.3, space = "HCL")),
HLS = rbind("0%" = cl,
"15%" = darken(cl, 0.15, space = "HLS"),
"30%" = darken(cl, 0.3, space = "HLS"))),
nrow = 4, line = 2.5
)
# darken light colors, example 2
cl <- c("#CDE4F3","#E7F3D3","#F7F0C7","#EFCFE5","#D0D1E7")
swatchplot(list(
combined = rbind("0%" = cl,
"15%" = darken(cl, 0.15),
"30%" = darken(cl, 0.3)),
HCL = rbind("0%" = cl,
"15%" = darken(cl, 0.15, space = "HCL"),
"30%" = darken(cl, 0.3, space = "HCL")),
HLS = rbind("0%" = cl,
"15%" = darken(cl, 0.15, space = "HLS"),
"30%" = darken(cl, 0.3, space = "HLS"))),
nrow = 4, line = 2.5
)