R ggplot2: annotation_custom of raster grob does not plot

Question

UPDATE Turns out it was an issue of not being able to produce raster graphics over a remote desktop connection.

I want to insert an image from file into a plot made with ggplot2. This question has already been asked here ( Inserting an image to ggplot2 ) but for me the accepted answer produces a plot devoid of any image. There are no errors or warnings: the axes, grid, and points all plot just fine but there's no R logo ( exported plot ; I couldn't upload an image here). Code below:

library(ggplot2)
library(png)
library(grid)

img <- readPNG(system.file("img", "Rlogo.png", package="png"))
g <- rasterGrob(img, interpolate=TRUE)

qplot(1:10, 1:10, geom="blank") +
  annotation_custom(g, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf) +
  geom_point()

I've tried playing around with the xy values and have used several different images and formats but to no avail.

The problem I'm having is specific to using a rastergrob object with annotate_custom(), as the examples given on the ggplot2 documentation site for annotate_custom() work just fine, eg:

library(gridExtra)

qplot(1:10, 1:10, geom = "blank") + 
  annotation_custom(grob = tableGrob(head(iris[ ,1:3])),
  xmin = 3, xmax = 6, ymin = 2, ymax = 8)

I'm using 64-bit R version 3.0.2 on windows with ggplot2 version 0.9.3.1 and my packages are all updated.

Any thoughts would be most welcome, and apologies if I'm missing something simple!

Answer 1

As explained in an answer to this question ( R base package grid does not produce output ), "R does not produce raster images correctly in the window device over Remote Desktop Connection. If a raster image is required, the plot must be output to another device."

I was accessing R using a Remote Desktop Connection and thus the raster grob would not plot.