OT: scanning (was: Re: scanning)

[Bob Rasmussen]

On Thu, 28 Oct 2010, Fairlight wrote:

> You -do- know that Windows itself has a twain.dll that you could
> theoretically build a utility or just PuTTY functionality around, right?

The Windows module (twain32.dll) is a common interface to the Twain 
drivers supplied by the various scanners. Talking to twain32.dll is like 
talking to the GDI to do printing. There are still a zillion details to 
deal with.

The interface itself is rather clunky, and has to be integrated with the 
calling application at a very low level, in order to provide event 
feedback. Every scanner is different. There are many possible features in 
the scanner, so there's some discovery that has to go on. The standard is 
vague in some areas, and some scanners don't appear to follow it 
precisely. 

There's a significant shortage of independent information about 
programming Twain. The official documentation of the standard is short on 
details.

Most manufacturers of scanners in the home/small office space have focused 
on providing a master scanning application for photos and documents. But 
many of the features supported at that level, such as optical character 
recognition or conversion to PDF, are not supported at the Twain driver 
level.

You might think I'm trying to scare you away from producing a free 
scanning product because I have one I'm trying to sell you. You'd be 
right ;-)

Regards,
....Bob Rasmussen,   President,   Rasmussen Software, Inc.

personal e-mail: ras at anzio.com
 company e-mail: rsi at anzio.com
          voice: (US) 503-624-0360 (9:00-6:00 Pacific Time)
            fax: (US) 503-624-0760
            web: http://www.anzio.com
 street address: Rasmussen Software, Inc.
                 10240 SW Nimbus, Suite L9
                 Portland, OR  97223  USA