Combining vector and bitmap graphics in a pdf

When plotting images or heatmaps to pdfs as in the example below they are 开发者_运维百科saved as vector objects where every pixel in the image or cell in the heatmap is represented by a square. Even at modest resolutions this results in unnecessarily large files that also renders uglily on some devices. Is there a way to make R save only the image area as a png or jpg embedded in the pdf but keep text, axes, anotations etc as vector graphics?

I'm asking since I am often printing R graphics, sometimes on large posters, and would like to combine the best of the two worlds. Of course I could save the entire figure as a high resolution png but that would not be as elegant, or combine it manually e.g. in Inkscape but it is quite tedious.

my.func <- function(x, y) x %*% t(y)
pdf(file="myPlot.pdf")
image(my.func(seq(-10,10,,500), seq(-5,15,,500)), col=heat.colors(100))
dev.off()

Thanks for your time, ideas and hopefully solutions!

Use ?rasterImage, or more conveniently in recent versions image with option useRaster = TRUE.

That will dramatically reduce the size of the file.

my.func <- function(x, y) x %*% t(y)
pdf(file="image.pdf")
image(my.func(seq(-10,10,,500), seq(-5,15,,500)), col=heat.colors(100))
dev.off()

pdf(file="rasterImage.pdf")
image(my.func(seq(-10,10,,500), seq(-5,15,,500)), col=heat.colors(100), useRaster = TRUE)
dev.off()

file.info("image.pdf")$size

file.info("rasterImage.pdf")$size

image.pdf: 813229 bytes

rasterImage.pdf 16511 bytes

See more details about the new features here:

http://developer.r-project.org/Raster/raster-RFC.html

http://journal.r-project.org/archive/2011-1/RJournal_2011-1_Murrell.pdf