Digital BW, The Print

As I am not familiar with adjusting dotgain, etc., descreening sounds like
the way to go. Also, it is impossible for me to discern typical halftone
dots on this image, even when examined under a loupe. The dots look much
more like film grain than they do like any photograph I've seen reproduced
in any book or magazine.

Assuming I go the descreening route and treat it as a continuous tone image,
any suggestions on how I should adjust the image (brightness curve,
sharpening, etc.) so that once printed it most closely resembles the
original postcard? Or is this something my friend will have to find out from
this particular service bureau?

Thanks much,

- David

-----Original Message-----
From: CDTobie@... [mailto:CDTobie@...]
Sent: Friday, May 03, 2002 11:36 AM
To: david_bookbinder@...;
DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] Scanning old postcard for use on book cover



In a message dated 5/3/02 10:54:04 AM, david_bookbinder@... writes:

>A friend of mine has asked me to scan an old postcard she will be using
>on a
>book cover. The postcard is in black and white, on time-yellowed stock.
>It
>will be positioned at a roughly 30% angle from horizontal on the book
cover.
>The service bureau wants a 300dpi TIFF file, and they are using a 150 line
>screen. I'm wondering:
>
>1. Do I need to take into account the dot pattern of the postcard somehow,
>and if so, how?

Since it is in B&W, you can scan at high res, and keep the original line
screen, instead of having it screened anew... by correcting the white point,
then converting to halftone with a percent threshold. You would need to
account for the presses dotgain by adjusting the percent of the dot
threshold, and perhaps reducing the dot size a bit more by selecting white,
enlarging the selection (how much depends on resolution) and deleting the
selection, to reduce the dot size.

Or you could give up on the original dots (simpler if you are not familiar
with this stuff) and run a descreen filter as you scan, then treat the file
as a typical continuous tone original.

C. David Tobie
Design Cooperative
CDTobie@...