Here are various ways of creating a png file. The dpi seems to be
treated inconsistently.
> quartz(width=7, height=7); plot(1:11); dev.copy2pdf()
produces a plot of 7x7 in, 2100x2100 pixels, 300 ppi. So dpi defaults to
300 - fair enough ... But
> quartz(width=7, height=7, dpi=72); plot(1:11); dev.copy2pdf()
also produces a plot of 7x7 in, 2100x2100 pixels, 300 ppi. So dpi=72 is
overruled with dpi=300.
Writing directly to file produces the opposite effect:
> quartz(width=7, height=7, type='png', dpi=300); plot(1:11); dev.off()
or
> png(width=7, height=7, units='in', res=300, type='quartz')
> plot(1:11); dev.off()
both produce plots of 7x7 in, 2100x2100 pixels, 72 ppi. So here dpi=300
is overruled with dpi=72.
The plot resolution is correct throughout, but writing directly to file
the dpi is wrong. Is there a way to force the file to have dpi=300?
I'm on R 2.11.1 GUI 1.34 Leopard build 32-bit (5589).
Thanks,
Tim
--
tim.c...@ich.ucl.ac.uk Phone +44(0)20 7905 2666 Fax +44(0)20 7905 2381
MRC Centre of Epidemiology for Child Health,
UCL Institute of Child Health, London WC1N 1EH, UK
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