GGplot geom to add custom PNG background to the plot

GGplot geom to add custom PNG background to the plot

geom_navr_background(image_path, xlim = NULL, ylim = NULL)

Arguments

image_path	path the png image
xlim	background poistions as vector of length 2, c(-100,400)
ylim	background poistions as vector of length 2, c(-100,400)