Convert Colors to Grey/Grayscale

Convert colors to grey/grayscale so that you can see how your plot will look after photocopying or printing to a non-color printer.

ColToGrey(col)
ColToGray(col)

Arguments

col: vector of any of the three kind of R colors, i.e., either a color name (an element of colors()), a hexadecimal string of the form "#rrggbb" or "#rrggbbaa" (see rgb), or an integer i meaning palette()[i]. Non-string values are coerced to integer.

Details

Converts colors to greyscale using the formula grey = 0.3*red + 0.59*green + 0.11*blue. This allows you to see how your color plot will approximately look when printed on a non-color printer or photocopied.

Value

A vector of colors (greys) corresponding to the input colors.

Note

These function was previously published as Col2Grey() in the TeachingDemos package and has been integrated here without logical changes.

Author

Greg Snow <greg.snow@imail.org>

Examples

par(mfcol=c(2,2))
tmp <- 1:3
names(tmp) <- c('red','green','blue')

barplot(tmp, col=c('red','green','blue'))
barplot(tmp, col=ColToGrey(c('red','green','blue')))

barplot(tmp, col=c('red','#008100','#3636ff'))
barplot(tmp, col=ColToGrey(c('red','#008100','#3636ff')))