Re: [Gimp-user] resolution, size when extracting from pdf vs. imagemagick

[Pat David <patdavid gmail com>]

Remember that as a container, pdf's can contain embedded jpg images at
varying pixel densities...

Christians solution would be the better solution I think.
On Tue, Jul 7, 2015 at 4:36 AM Joel Rees <joel rees gmail com> wrote:

> 2015/07/07 16:55 "Christian Mandel" <c mandel gmx net>:
> > For this use case,
>
> Well, actually, even IM's default 72 px/in would have done my present job.
> However,
>
> > I would suggest using the pdfimages program (from xpdf I guess)
> > (with the -j option to preserve embedded jpg) to extract the original
> images.
>
> this is all useful information.
>
> > The import in gimp will always "render" the pdf, what will always scale
> the original image,
> > unless you hit the exact resoultion/size.
> > Even then some quality will be lost since the pixel data from the
> rendered image will be taken and not the original information.
> > IIRC, neither IM nor Gimp will look into the pdf "container" to check the
> original jpeg's resolution, they assume a default resolution which you can
> change as Pat suggests.
> > Best regards
> >
> > Chris
>
> Thanks.
>
> > Am 07.07.2015 um 09:00 schrieb Joel Rees:
> > > I have a pdf of scanned images, theoretically jpeg images, and the gimp
> > > will offer me a selection dialog, from which it will import them
> > > individually as 1304x932 at 100 px/in. (This is odd, because I selected
> > > 300dpi at scan time, so the images should be 3 times that pixel density.
> > > But, then, 22Mb for 36 images is not 13" x 9" at 300 dpi, unless heavily
> > > compressed.)
> > >
> > > ImageMagick's identify -verbose tells me the same are 1032x728 at 72
> dpi.
> > > If I use ImageMagick's convert to extract them, that's how they end up.
> > >
> > > Anyone have an idea what's happening?
> > >
> > > Joel Rees
> > >
> > > Computer memory is just fancy paper,
> > > CPUs just fancy pens.
> > > All is a stream of text
> > > flowing from the past into the future.
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