This function lets you convert between different representations of colours.
The API is reminiscent of grDevices::convertColor(), but the performance is
much better. It is not assured that grDevices::convertColor() and
convert_colour() provide numerically equivalent conversion at 16bit level as
the formula used are potentially slightly different. For all intend and
purpose, the resulting colours will be equivalent though.
convert_colour(colour, from, to, white_from = "D65", white_to = white_from)A numeric matrix (or an object coercible to one) with colours
encoded in the rows and the different colour space values in the columns. For
all colourspaces except 'cmyk' this will mean a matrix with three columns -
for 'cmyk' it means four columns.
The input and output colour space. Allowed values are: "cmy",
"cmyk", "hsl", "hsb", "hsv", "lab" (CIE L*ab), "hunterlab"
(Hunter Lab), "oklab", "lch" (CIE Lch(ab) / polarLAB), "luv",
"rgb" (sRGB), "xyz", "yxy" (CIE xyY), "hcl" (CIE Lch(uv) / polarLuv),
or "oklch" (Polar form of oklab)
The white reference of the from and to colour
space. Will only have an effect for relative colour spaces such as Lab and
luv. Any value accepted by as_white_ref() allowed.
A numeric matrix with the same number of rows as colour and either
3 or 4 columns depending on the value of to. If colour is given as a
data.frame the output will be a data.frame as well
This function and convertColor() are not
numerically equivalent due to rounding errors, but for all intend and purpose
they give the same results.
NA, NaN, -Inf, and Inf are treated as invalid input and will result
in NA values for the colour. If a given colourspace has finite bounds in
some of their channels, the input will be capped before conversion, and the
output will be capped before returning, so that both input and output colours
are valid colours in their respective space. This means that converting back
and forth between two colourspaces may result in a change in the colour if
the gamut of one of the spaces is less than the other.
spectrum <- decode_colour(rainbow(10))
spec_lab <- convert_colour(spectrum, 'rgb', 'lab')
spec_lab
#> l a b
#> [1,] 53.24079 80.09796 67.20432
#> [2,] 72.26072 30.17136 77.22610
#> [3,] 93.60533 -41.93879 90.27635
#> [4,] 88.07403 -83.10282 83.59544
#> [5,] 88.19634 -80.27407 57.92961
#> [6,] 91.11322 -48.08151 -14.12690
#> [7,] 47.90478 35.20130 -82.00196
#> [8,] 33.81896 79.70472 -105.27489
#> [9,] 51.90416 91.00028 -74.83009
#> [10,] 55.65103 86.53436 -9.71618
# Convert between different white references
convert_colour(spec_lab, 'lab', 'lab', white_from = 'D65', white_to = 'F10')
#> l a b
#> [1,] 53.24080 78.60861 61.96368
#> [2,] 72.26073 28.55590 69.69829
#> [3,] 93.60534 -43.63249 80.36298
#> [4,] 88.07403 -84.54076 73.96892
#> [5,] 88.19634 -81.72521 45.70399
#> [6,] 91.11322 -49.70878 -34.09510
#> [7,] 47.90478 33.97911 -101.30502
#> [8,] 33.81896 78.54632 -124.47620
#> [9,] 51.90416 89.49072 -94.10538
#> [10,] 55.65103 84.97882 -23.10021