OT: scanning (was: Re: scanning)

[Fairlight]

On Fri, Oct 29, 2010 at 06:06:38AM -0700, after drawing runes in goat's blood,
Bob Rasmussen cast forth these immortal, mystical words:
> 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.

He's dealing with C code...should be par for the course.  :)
> 
> 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. 

That's a shocker.  :)

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

This explains why TWAIN captures from various scanners and cameras seem to
fail 80%+ of the time when I tried them.  I use other methods of getting my
data nowadays...mfgr-supplied scan software and SD cards or USB transfers.

> 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.

OCR is a nightmare to even think about coding.  Even SnagIt's text capture
is a failure on, say, a browser window or a terminal emulator.  Loses or
gets lots of characters  wrong.  Works perfectly on Windows Explorer or
other Windows-generated windows, but I think it accesses the objects
directly then...or handles system fonts better.  Likely cheats...never seen
it mess up a directory listing.

> 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 ;-)

No trouble to me...it's Brian's gig...  I've just tried to be helpful.

To say it's a non-trivial project to code scanning and/or OCR is
understatement, and I know it.  Anyone with a clue should.  I think your
market share is safe.  :)

mark->
-- 
Audio panton, cogito singularis.