Hi, For curiosity's sake, below is another version with ggplot2 and Grid graphics,
library(pixmap) logo <- read.pnm(system.file("pictures/logo.ppm", package="pixmap")[1]) library(ggExtra) # r-forge, requires gridExtra qplot(rnorm(100),rnorm(100)) + annotate("pixmap", x=-Inf, y=-Inf, picture=logo, vjust=0, hjust=0, raster=T) baptiste On 18 November 2010 20:47, Paul Murrell <p...@stat.auckland.ac.nz> wrote: > Hi > > Rajarshi Guha wrote: >> >> Hi, I have a plot and I would like to overlay a PNG image over it. I'm >> using the rasterImage function to do this, but the problem I'm facing >> is working out the coordinates of the upper right corner of the final >> image in user coordinates. >> >> That is I can place the image so the lower left is located at the >> bottom of the y-axis and the left end of the x-axis. Since my image is >> say 100px x 100px, is there a way for me to convert a 100px length >> into the appropriate value in user coordinates, along the x-axis? > > Are you trying to draw the image at its "native" resolution? > > R should be able to scale the image using interpolation to whatever size you > want, but if you really want to try for native resolution, this should get > you close ... > > # Import a raster image > library(pixmap) > logo <- read.pnm(system.file("pictures/logo.ppm", package="pixmap")[1]) > > # Image size > l...@size > > # A plot > plot(rnorm(100), rnorm(100)) > > # If you know the screen resolution, use that, otherwise > # the device may be telling R something close to the truth > dpi <- (par("cra")/par("cin"))[1] > > usr <- par("usr") > xl <- usr[1] > yb <- usr[3] > xr <- xl + xinch(l...@size[2]/dpi) > yt <- yb + yinch(l...@size[1]/dpi) > > # Image at "native" resolution > rasterImage(matrix(rgb(l...@red, l...@green, l...@blue), > nrow=l...@size[1]), > xl, yb, xr, yt) > > > Paul > >> Thanks, >> >> > > -- > Dr Paul Murrell > Department of Statistics > The University of Auckland > Private Bag 92019 > Auckland > New Zealand > 64 9 3737599 x85392 > p...@stat.auckland.ac.nz > http://www.stat.auckland.ac.nz/~paul/ > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.