[R] embed image (png) in postscript (device)

Prof Brian Ripley ripley at stats.ox.ac.uk
Fri Sep 1 16:24:57 CEST 2006

On Fri, 1 Sep 2006, Hans-Peter wrote:

> Hi,
> I output multiple "grid-package-based" plots to the postscript device.
> Because the graphics are complicated and consists of a lot of datapoints
> (~200'000) the files become really big. To avoid this big files and to
> shorten the creation, I currently print the plots to the png device and
> manually combine them into one multipaged pdf document.
> My question is, it is possible to do this in R directly?
> Probably I would have to create a png plot first, then reimport it into R
> and "put" it on the ps device. Is this a realistic way (in principle) ?
> If there is no package to read png files (I didn't find anything), I
> probably could solve this. 

There are various ways to do so: one is to convert to a format pixmap 
knows, another to convert to TIFF and use rtiff.

> But I still don't know if it would be possible to
> "put" this memory representation to a ps device.

Only crudely.  There is nothing in the R graphics model related to 
bitmaps.  What you could do is draw each pixel as a rectangle (as image() 
does), but then your file size will be even bigger and the chances of it 
being rendered accurately are not high.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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