Convert RGB color triplets to discrete color labels

This function classifies an RGB color triplet into one of the discrete color categories defined in the Color Look-Up Table (CLUT) by testing for membership within non-overlapping HSV ranges.

Usage

color2label(color_triplet, verbose = FALSE, clut = charisma::clut)

Arguments

color_triplet: Numeric vector of length 3 containing RGB values (0-255 scale). The vector should be c(red, green, blue).
verbose: Logical. If TRUE, prints the color triplet and classification results for debugging. Default is FALSE.
clut: Data frame containing the Color Look-Up Table with HSV boundaries for each color class. Default is charisma::clut.

Value

Character string indicating the matched color label from the CLUT. Returns "NA" if the input contains NA values.

Details

The classification process involves:

Converting RGB to HSV (using rgb2hsv)
Scaling HSV to match CLUT ranges (H: 0-360, S: 0-100, V: 0-100)
Testing the HSV coordinate against all color definitions in the CLUT
Returning the single matching color label

Each color in the CLUT has non-overlapping HSV ranges that partition the entire HSV color space. If multiple matches occur, a warning is issued as this indicates overlapping color boundaries in the CLUT.

References

Schwartz, S.T., Tsai, W.L.E., Karan, E.A., Juhn, M.S., Shultz, A.J., McCormack, J.E., Smith, T.B., and Alfaro, M.E. (2025). charisma: An R package to perform reproducible color characterization of digital images for biological studies. (In Review).

Examples

# Classify a blue RGB color
color2label(c(0, 0, 255))
#> [1] "blue"

# Classify a red RGB color
color2label(c(255, 0, 0))
#> [1] "red"

# Verbose output for debugging
color2label(c(128, 128, 128), verbose = TRUE)
#>   h s         v
#> 1 0 0 0.5019608
#>  black  white   grey  brown    red orange yellow  green   blue purple 
#>      0      0      1      0      0      0      0      0      0      0 
#> [1] "grey"