tidbitR - Adding an image watermark to ggplot

In this example, let’s see how to add an image watermark to ggplot. Can either use png or jpeg to load a png or a jpeg.

library(ggplot2)

df <-
  data.frame(
    key = c("Compliance", "Information Technology"),
    budget = c(25000, 15000)
  )

img <- png::readPNG("./watermark.png")

## Warning in png::readPNG("./watermark.png"): libpng warning: iCCP: known
## incorrect sRGB profile

rast <- grid::rasterGrob(img, interpolate = T)

Here is the example.

ggplot(data = df) +
  annotation_custom(rast, ymin = 24000, ymax = 27000, xmin = 2) +
  geom_bar(aes(x=key, y = budget), stat = "identity", alpha = 0.8)

ggplot(data = df) +
  annotation_custom(rast, ymin = 24000, ymax = 27000, xmin = 2) +
  geom_bar(aes(x=key, y = budget), stat = "identity", alpha = 0.8) +
  facet_wrap(~key)

So far I couldn’t find another way to put an image that will give an easier way to set the size and placement of the image.