colorRamp2 (version 0.1.0)

col2value: Convert back from colors to values

Description

Convert back from colors to values

Usage

col2value(r, g, b, col_fun)

Value

A vector of original numeric values.

Arguments

r

Red channel in sRGB color space. Value should be between 0 and 1. The value can also be a character vector of colors or a three-column matrix with r, g, b as columns. In this case, g and b are ignored,

g

Green channel in sRGB color space. Value should be between 0 and 1.

b

Blue channel in sRGB color space. Value should be between 0 and 1.

col_fun

the color mapping function generated by colorRamp2.

Author

Zuguang Gu <[e-mail]>

Details

colorRamp2 maps values to colors and this function does the reversed job. Note for some color spaces, it cannot convert back to the original value perfectly.

Examples

x = seq(0, 1, length.out = 11)
col_fun = colorRamp2(c(0, 0.5, 1), c("blue", "white", "red"))
col = col_fun(x)
col2value(col, col_fun = col_fun)
col2value("red", col_fun = col_fun)

col_fun = colorRamp2(c(0, 0.5, 1), c("blue", "white", "red"), space = "sRGB")
col = col_fun(x)
col2value(col, col_fun = col_fun)