Create LAB Colors

This function creates colors of class “LAB”; a subclass of the virtual color-class class.

LAB(L, A, B, names)

Arguments

L, A, B

these arguments give the L, A and B coordinates of the colors. The values can be provided in separate L, A and B vectors or in a three-column matrix passed as L.

names

a vector of names for the colors (by default the row names of L are used).

Value

An object of class LAB which inherits from class color.

Details

The L, A and B values give the coordinates of the colors in the CIE \(L^*a^*b^*\) space. This is a transformation of the 1931 CIE XYZ space which attempts to produce perceptually based axes. Luminance takes values between 0 and 100, and the other coordinates typically take values between -100 and 100, although these values can also be exceeded by highly saturated colors. The \(a\) and \(b\) coordinates measure positions on green/red and blue/yellow axes.

See also

RGB, HSV, XYZ, LAB, polarLAB, LUV, polarLUV.

Author

Ross Ihaka

Examples

## Show the LAB space
set.seed(1)
x <- sRGB(runif(1000), runif(1000), runif(1000))
y <- as(x, "LAB")
head(x)
#>              R         G        B
#> [1,] 0.2655087 0.5308088 0.871805
head(y)
#>             L        A         B
#> [1,] 56.02127 6.894485 -50.58648
plot(y)