alphablend: Perform alpha blending for pairs of RGBA colors.
Description
Implements the *over* alpha blending operation.
Usage
alphablend(front_color, back_color, silent = TRUE)
Arguments
front_color
rgba color strings, the upper color layer or foreground
back_color
rgba color strings, the lower color layer or background
silent
logical, whether to suppress messages
Value
rgba color strings, the alpha-blended colors
References
see the *Alpha blending* section on https://en.wikipedia.org/wiki/Alpha_compositing