Convert RGB Colors to the Nearest Named R Color

Finds, for each color, the perceptually closest of the named R colors (grDevices::colors()).

Usage

rgbToCol(col, method = c("ciede2000", "cie76"))

Arguments

col

colors: an RGB matrix with one color per column and channels on a scale from 0 to 255, as returned by colToRgb(), or a vector of R colors (hexadecimal or named). An alpha channel is ignored.

method

color difference formula, "ciede2000" (default) or "cie76", see Details.

Value

Character vector of named R colors, one per color in col; NA for a missing color.

Details

The colors are converted from sRGB to the CIELAB color space with grDevices::convertColor() (reference white D65), where distances approximate perceived differences far better than in RGB or HSV. Two color difference formulas are available:

"ciede2000"

CIEDE2000, the current CIE recommendation. It corrects the shortcomings of CIE76 in the blue region and for saturated and near-neutral colors.

"cie76"

CIE76, the Euclidean distance in CIELAB. Simpler, slightly less accurate.

References

Sharma, G., Wu, W., & Dalal, E. N. (2005). The CIEDE2000 color-difference formula: Implementation notes, supplementary test data, and mathematical observations. Color Research & Application, 30(1), 21–30. doi:10.1002/col.20070

See also

color-conversion-overview

Examples

rgbToCol(matrix(c(162, 42, 42), nrow = 3))
#> [1] "brown"
rgbToCol(c("#A22A2A", "#4169E0"))
#> [1] "brown"     "royalblue"

# CIE76 instead of CIEDE2000
rgbToCol(c("#A22A2A", "#4169E0"), method = "cie76")
#> [1] "brown"     "royalblue"