Re: SUMMARY: Re: "Print on demand" and "Docutech"

["Graham Wyatt" <graham -at- gpwyatt -dot- co -dot- uk>]

Hi everybody,

I just thought I would jump in with a few additional comments on the use of
Docutechs. We've done quite a lot of this over the years, and my experience
is generally very positive. Docutechs seem to be a good example of how you
can make a lot of difference to the finished results by designing for the
output medium, and then tweaking the output settings accordingly.

>
>    The docutech prints at about 600 dpi.
>

It is claimed to be 600 dpi, but the output is of much higher quality than I
get from my 600 dpi LaserJet. I think that this is because the toner that
the Docutech uses is much finer than ordinary laser toner. One consequence
of this is that tints are usually rendered much lighter than they appear in
the laser output. At average screen settings a 5% tint will almost disappear
on the page, so for most applications use 10% as a minimum.

>
>    "Some vendors will also accept .pdf files, but the quality of print may
>    be marginally lower."

As far as the Docutech is concerned, a PDF file _is_ a PS file and, so as
long as the PDF has been set up correctly, there should be no difference in
print quality. Both of the vendors that I have used have preferred PDF
files, and they are much easier to send by email.

The biggest variable in quality is in the way that a Docutech renders
greyscales, and you can control this by adjusting the screen settings in
your PS output.  If you have a document that includes photographs or
graphics with graduated blends, use a low setting (around 85lpi). If the
document contains a limited range of flat tints, use a high setting (up
120lpi). This will make the tints really crisp, and will also darken them a
little.

If your document contains a mixture of flat tints and graduates, you may
find that your application will allow you to set individual screens for each
graphic. If not, it is still possible to output individual pages at
different screen settings. We've done this several times with cover pages
and it has worked very well. However, if you are going to do this warn the
operator, because I think that it is possible for the Docutech RIP to
override any custom screen settings.

I've not made use of a colour Docutech, but it is possible to introduce
colour into a B/W document by using pre-printed paper containing repeating
elements. This means that you can have a colour logo, background graphic, or
one of those tinted panel that bleeds to the edge for page numbers, and of
course you can use different stationary for different parts of the book. The
finished result can look very good, and you will retain all the benefits of
print on demand.

The only limitation is that the ink used for pre-printing must be capable of
withstanding the heat of the Docutech's fuser rollers   Again, talk to the
operator about it.

Graham Wyatt



GP Wyatt Technical Services Ltd
Training and Product Documentation Specialists
mail: graham -at- gpwyatt -dot- co -dot- uk
Brochure at: http://www.gpwyatt.co.uk