How do we plot images at given coordinates in R?

Given 'n' images in a png/jpeg format and 'n' corresponding coordinates in 2 dimensions (x,y): I would like to plot these images at the given coordinates on a single plot. If I find the images to be too big, I would ideally like to plot them as a smaller/scaled version at the given coordinates. How can i achieve such a plot in R?

An example of how such a plot would look is given below:

enter image description here

Solution

xy <- data.frame(x=runif(10, 0, 100), y=runif(10, 0, 100))

require(png)
img <- readPNG(system.file("img", "Rlogo.png", package="png"))

thumbnails <- function(x, y, images, width = 0.1*diff(range(x)), 
                       height = 0.1*diff(range(y))){

  images <- replicate(length(x), images, simplify=FALSE)
  stopifnot(length(x) == length(y))

  for (ii in seq_along(x)){
    rasterImage(images[[ii]], xleft=x[ii] - 0.5*width,
                ybottom= y[ii] - 0.5*height,
                xright=x[ii] + 0.5*width, 
                ytop= y[ii] + 0.5*height, interpolate=FALSE)
  }
}

plot(xy, t="n")
thumbnails(xy[,1], xy[,2], img)

enter image description here