Colormixing in HSV space

Vectorized approximation of additive-type color mixing using the HSV colorspace. Intended for helping in plotting more than one variable at the same time and showing how they overlap.
Since the mixing is performed using HSV, this function interpolates hue mixtures, however due to the orthogonal nature of HSV, it does not imitate the ability to generate white from red, green, and blue which the RGB colorspace would be better at. However, this limitation is fine for this use case which prioritizes clearly understandable mixtures of 2 or more colors. Additionally, the orthogonal nature of saturation and value to hue allows either of them to be treated as the absence of signal or alpha when mixing to match with plotting backgrounds. Treating either white or black as the base color makes it so that either saturation or black, respectively, are treated as alpha, applying a weighting to c1 or c2 values during mixing.

Usage

mixHSV(c1, c2, base_color = c("white", "black"), output = c("hex", "hsv"))

Arguments

c1, c2

Colors 1 and 2. Accepts vector of hex color codes or an hsv matrix

base_color

either "white" (default) or "black". Which color to treat as the absence of signal in c1 and c2

output

either "hex" or "hsv". "hex" produces a vector of hex codes for color mixtures. "hsv" returns the hsv matrix.

Value

a vector of hex codes or an hsv matrix

See also

Other colormixing functions: mixRGB()

Examples

# with black background
a <- GiottoVisuals::simple_palette_factory(c("green", "black"))(255)
b <- GiottoVisuals::simple_palette_factory(c("red", "black", "blue"))(255)
x <- mixHSV(a, b, base_color = "black")

op <- par(no.readonly = TRUE)
par(bg = "black")

# plot input color vectors
plot(seq(255),
    y = rep(2, 255), col = a, pch = 15, ylim = c(0, 3),
    bg = "black"
)
points(seq(255), y = rep(1.5, 255), col = b, pch = 15)
# plot mixture
points(seq(255), y = rep(1, 255), col = x, pch = 15)


par(op)

# with white background
a <- GiottoVisuals::simple_palette_factory(c("green", "white"))(255)
b <- GiottoVisuals::simple_palette_factory(c("red", "white", "blue"))(255)
x <- mixHSV(a, b, base_color = "white")

plot(seq(255),
    y = rep(2, 255), col = a, pch = 15, ylim = c(0, 3),
    bg = "black"
)
points(seq(255), y = rep(1.5, 255), col = b, pch = 15)
points(seq(255), y = rep(1, 255), col = x, pch = 15)