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Topic: Re: Compressing PDFs (Via Email)
Conf: (P-PDF) General, Msg: 82366
From: duffj
Date: 3/6/2003 06:11 AM

>I am involved in a project to create PDFs of 19th century texts for
>download on the Web. The files that were given to me are 600dpi tifs,
and
>we want to convert these tifs into a single pdf. We also want to make
>these image-based pdfs text searchable, which I use Capture for (and I
>understand that making them text searchable will only add to the file
size).
>However, when I compress using either Capture or Distiller, I get either
a)
>really bad quality, or b) no decrease in file size.
>
>Anyone have any ideas on the best method of compression?

It's not clear if your TIFFs are bitonal or not... I hope they are
bitonal. If they are color, you are in a world of hurt - in which case I
would suggest that you seek professional help (me).

Unless you REALLY have to put the 600 dpi files online, first downsample
your TIFFs to 300 dpi before sending them through capture. There are a
number of utilities that will allow you to resample TIFFs.

If they are bitonal, and if you are using Capture 3.0, then you can
compress them with JBIG2 compression, which will reduce file-size a lot -
at the price of forcing users to Acrobat 5.0x and higher.

Note that it's very important to feed high-quality images to Capture - it
makes a big difference in OCR accuracy AND compression efficiency.

Duff Johnson
Document Solutions, Inc.
www.document-solutions.com