opticut (version 0.1-3)

occolors: Color Palettes for the opticut Package

Description

A convenient way of setting color palettes for the opticut package.

Usage

occolors(theme)
col2gray(col, method="BT.709")

Value

occolors returns a function, see colorRampPalette.

col2gray returns a vector of gray colors based on the conversion method and gray.

Arguments

theme

character value, character vector, or a function used to interpolate the colors. The built-in values are "br" (default, blue-red divergent palette, colorblind safe), "gr" (green-red divergent palette), "bw" (black and white: grayscale converted "br" settings). See colorRampPalette, gray and the Examples.

col

vector of color specification as described on the help page for the col2rgb function. This is converted to grayscale.

method

character, the method used for grayscale conversion. See Details.

Author

Peter Solymos <[e-mail]>

Hexadecimal values for the built-in palettes are taken from https://colorbrewer2.org/.

Converting color to grayscale: https://en.wikipedia.org/wiki/Grayscale

Details

Grayscale conversion methods in col2gray calculate gray levels based on red (R), green (G), and blue (B) color channels as follows:

"BT.709"

0.2126 * R + 0.7152 * G + 0.0722 * B, luminosity correction following the ITU-R BT.709 recommendation;

"BT.601"

0.299 * R + 0.587 * G + 0.114 * B, luminosity correction following the ITU-R BT.601 recommendation;

"desaturate"

(max(R, G, B) + min(R, G, B)) / 2, also called lightness;

"average"

(R + G + B) / 3;

"maximum"

max(R, G, B);

"minimum"

min(R, G, B);

"red"

R;

"green"

G;

"blue"

B.

See Also

colorRampPalette for a general description of palettes.

ocoptions for setting the color theme option in the opticut package.

Examples

## using palettes
plot(1:100, rep(2, 100), pch = 15,
    ylim = c(0, 21), axes = FALSE, ann = FALSE,
    col = occolors()(100)) # default 'bg'
text(50, 1, "theme = 'br'")
points(1:100, rep(5, 100), pch = 15,
    col=occolors("gr")(100))
text(50, 4, "theme = 'gr'")
points(1:100, rep(8, 100), pch = 15,
    col=occolors("bw")(100))
text(50, 7, "theme = 'bw'")
points(1:100, rep(11, 100), pch = 15,
    col=occolors(terrain.colors)(100))
text(50, 10, "theme = terrain.colors")
points(1:100, rep(14, 100), pch = 15,
    col=occolors(c("purple", "pink", "orange"))(100))
text(50, 13, "theme = c('purple', 'pink', 'orange')")
points(1:100, rep(17, 100), pch = 15,
    col=occolors(c("#a6611a", "#ffffbf", "#018571"))(100))
text(50, 16, "theme = c('#a6611a', '#ffffbf', '#018571')")
points(1:100, rep(20, 100), pch = 15,
    col=occolors(c("#7b3294", "#ffffbf", "#008837"))(100))
text(50, 19, "theme = c('#7b3294', '#ffffbf', '#008837')")

## grayscale conversions
n <- 25
col <- occolors("br")(n)
method <- c("BT.709", "BT.601",
    "desaturate", "average", "maximum", "minimum",
    "red", "green", "blue")
plot(0, type="n", ann=FALSE, axes=FALSE,
    xlim=c(0, n), ylim=c(3*length(method), 0))
for (j in 1:length(method)) {
    for (i in 1:n) {
        polygon(c(i-1, i, i, i-1), c(0, 0, 1, 1)+((j-1)*3),
            col=col[i], border=col[i])
        polygon(c(i-1, i, i, i-1), c(1, 1, 2, 2)+((j-1)*3),
            col=col2gray(col[i], method=method[j]),
            border=col2gray(col[i], method=method[j]))
        text(n/2, 1+((j-1)*3), method[j])
    }
}