Converting a bunch of pdf files to pnm without loosing resolution

[Aaron Konstam]

On Sat, 2007-08-25 at 16:49 +0100, Paul Smith wrote:
> On 8/25/07, Andy Green <andy at warmcat.com> wrote:
> > >>> Is there any way of converting a bunch of pdf files to pnm without
> > >>> loosing resolution?
> > >> What happens when you use the -dpi= option on pstopnm?
> > >
> > > OK, Andy, but how can one find out the dpi's of our pdf file?
> >
> > Well the pdf is not normally already rasterized in the case of text, so
> > for that there is no "dpi of our pdf file".  It will render the text
> > nicely according to the dpi you asked for.
> >
> > If there are raster images (at various dpi) in the pdf then it will
> > scale them to the dpi you asked for AIUI.  So I guess you should pick a
> > dpi that is close to the highest image dpi in the pdfs (eg, 300) and run
> > with it.
> 
> Thanks, Andy. In fact, the pdf file that I have got contains a scanned
> document. Is there some way of determining the dpi used in the
> scanning work?
> 
> Paul

Ok., I finally was pressed to resolve my confusion. The question was to
convert a pdf file t0 pnm. pstopnm converts ps files to pnm. What am I
missing?
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Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam at sbcglobal.net