PDF "resolution"

On 08/07/2007 10:31 PM, "Edward Reid" <edwardpaleo.org> spake thus:

> Yes, a PDF can include bitmapped graphics. But that's not it's natural
> mode, and does not apply to text.

While it's not really bitmapped text per se, if you happen to use Type 3
fonts in a document, they look like complete crap on screen at any zoom
level, but print fine. This can be quite common with LaTeX-produced
documents, although things have improved considerably in that regard in
recent years. Perhaps that's what's happened with this document.

--
Nigel Stanger, Dunedin, NEW ZEALAND.
http://xri.net/=nigel.stanger

Edward wrote:
>> a low-resolution PDF of a book
>
> Since you're clearly talking about text, there's no such
> thing as a low
> resolution PDF. It's all vector graphics. Display it in Adobe
> Reader and
> push the magnification up to 6400%. Corners and edges remain sharp.
>
> Yes, a PDF can include bitmapped graphics. But that's not it's natural
> mode, and does not apply to text.

Perhaps he meant a book that has been scanned, then put into a PDF.
You'd basically end up with a series of images inside a PDF container.
Hardly useful, but it's been known to happen.

Harro de Jong

Harro de Jong wrote:
> Edward wrote:
>>> a low-resolution PDF of a book
>> Since you're clearly talking about text, there's no such
>> thing as a low
>> resolution PDF. It's all vector graphics. Display it in Adobe
>> Reader and
>> push the magnification up to 6400%. Corners and edges remain sharp.
>>
>> Yes, a PDF can include bitmapped graphics. But that's not it's natural
>> mode, and does not apply to text.
>
> Perhaps he meant a book that has been scanned, then put into a PDF.
> You'd basically end up with a series of images inside a PDF container.
> Hardly useful, but it's been known to happen.
>
Actually happens all the time these days. Many copier/scanner/printers will scan to a PDF and email it to you. The hassle comes from folks not realizing this result isn't the same as printing the original to a PDF file.

David

On 10/07/2007 6:12 AM, "Harro de Jong" <hdjongtriview.nl> spake thus:

> You'd basically end up with a series of images inside a PDF container.
> Hardly useful, but it's been known to happen.

Actually, extremely useful for old material which has no digital original,
especially if you create hybrid PDFs that have bitmapped images of the pages
so that they're readable and printable, but also hidden OCR text from the
scans so that they're searchable.

We've been doing quite a lot of this here with old postgraduate theses so we
can load them into our School's institutional repository. OCR'ing them to a
"real" PDF just isn't economic given the number of OCR errors that need to
be fixed.

--
Nigel Stanger, Dunedin, NEW ZEALAND.
http://xri.net/=nigel.stanger

Nigel Stanger wrote:

> On 10/07/2007 6:12 AM, "Harro de Jong" <hdjongtriview.nl> spake thus:
>
>> You'd basically end up with a series of images inside a PDF
>> container. Hardly useful, but it's been known to happen.
>
> Actually, extremely useful for old material which has no
> digital original,
> especially if you create hybrid PDFs that have bitmapped
> images of the pages
> so that they're readable and printable, but also hidden OCR
> text from the
> scans so that they're searchable.

Well yes, but the OCR step is what makes them usable. IMO, you'd also
need to add bookmarks, though. My comment was more about PDFs that
didn't have these features: it's better than nothing, but extracting
information from the book becomes rather awkward.

Harro de Jong

At 11:12 07/09/07 -0700, Harro de Jong wrote:
>Perhaps he meant a book that has been scanned, then put into a PDF.

For once, I left too little quoted material. The original was from Adam's
TidBITS article about PDFPen, which said

> The modern solution to non-destructive editing is PDF - you can send
> a low-resolution PDF of a book to a proofreader, who can then use
> Adobe Acrobat to indicate changes.

In that context, it was clear that the PDFs under consideration were
ordinary text.

Edward
--
Art works by Melynda Reid: http://paleo.org

--On July 12, 2007 3:07:20 AM -0700 Edward Reid <edwardpaleo.org> wrote:

>> The modern solution to non-destructive editing is PDF - you can send
>> a low-resolution PDF of a book to a proofreader, who can then use
>> Adobe Acrobat to indicate changes.
>
> In that context, it was clear that the PDFs under consideration were
> ordinary text.

Although most books for publishing these days do contain mixed media, and
reducing the resolution of all the inserted images can definitely reduce
the size of a pdf.

Basically Edward is saying the resolution of a PDF only affects inserted
raster images, be it from scanners or cameras. It is even possible to
insert line work from programs such as Illustrator as vector data, which
like type, also has no resolution. PDF even supports 3D images from several
CADD/3D packages as vector work (although textures may be raster data). I
don't believe there are any third party viewers that support displaying the
3D components yet, I think that requires Adobe's Reader currently.

At 3:31 AM -0700 7/8/07, Edward Reid wrote:
>For once, I left too little quoted material. The original was from Adam's
>TidBITS article about PDFPen, which said
>
>> The modern solution to non-destructive editing is PDF - you can send
>> a low-resolution PDF of a book to a proofreader, who can then use
>> Adobe Acrobat to indicate changes.
>
>Since you're clearly talking about text, there's no such thing as a low
>resolution PDF. It's all vector graphics. Display it in Adobe Reader and
>push the magnification up to 6400%. Corners and edges remain sharp.
>
>Yes, a PDF can include bitmapped graphics. But that's not its natural
>mode, and does not apply to text.
>
>In that context, it was clear that the PDFs under consideration were
>ordinary text.

To explain my "low-resolution" comment - when you're creating a PDF
to send to a proofreader, it's not necessary for the screenshots to
be at their original full resolution. So when creating the PDF, you
intentionally downsample the images heavily so the resulting PDF is
much smaller and easier to send.

Text is unrelated to this, of course, but it's not desirable to have
a proofreader working in a version of the book that doesn't include
images.

cheers... -Adam