Does anyone know anything about how scanners (hand scanners in particular)
transfer info down their wires and end up in your PC?  I'm looking to do a
little development with a scanner (I don't have one to play with yet), and
would like a little info.  Any references would also be appreciated.

21 responses total.

I saw some articles in Byte ro PC magazine a while ago (6mo?).

ThunderScan made a unit that replaced the ribbon in an ImageWriter
printer.  It had a light source and a photo-diode which would decide
what level of intensity the reflected light was and assign it a digital
level.  The image you wanted to scan was rolled into the printer and 
the printer motors were used to "scan" the image.
Newer, more expensive, scanners use CCD's (Charge Coupled Devices) which
can be thought of as an aray of photo-diodes.  Hand scanners have little
wheels on the bottom which roll along the surface of the image your
scanning.  These are connected to a digital encoder which give the hardware/
software posistional information.  This way jerky hand motion can still
give you a non-distorted picture.  Table scanners use the same basic idea,
except they move the scanner head across the fixed image.  Add color by
putting optical filters in front of the seperate CCD elements or photodiode.

Most of the higher-end scanners interface to the computer via the
SCSI bus.  This has the advantage of being relatively standard, as
well as available on a number of different hardware platforms (Mac,
PC, Amiga, various workstations, etc.).  The lower-end scanners,
like low-end CD-ROM drives, tend to use a proprietary interface
that may or may not resemble SCSI.

For the record, I have a PC, not a Mac.

Thanks for the hardware summary, but I was really interested in whats
coming down the wire, or port as the case may be.  Are hand scanners different
in this respect?

I'll look through the old Bytes and PCMags at work, monday.

Thanks all!

Keep it coming!

Dunno what the actual data format looks like.  You may or may not
be able to get specs on it from the manufacturer of your scanner
(that is, if you already have one).  I'm not sure if there's
a standard of some sort, or if every manufacturer decided to come
up with their own.

That's what I'm going to try next.  Unfortuneatly, I don't own a scanner as
of yet.  I'm looking for just a cheapee that I can play with for very little
$$$.  Used is the current prospect.

No one would by chance have addresses of scanner makers would they?

I'vee used a couple of scanners, both hand- and bed- types, adn they
(both on PC's and Mac's) both work about as well as they should for
the money. The flat-bed stuff is dropping in price as I type. The
hand scanners have a loooooooong roller to assist in scanning in a
straight line. It's mostly a practice thing, geting it straight to
begin with- not all that much though and for the money ....
   
The real bottle neck isthe software you use and whether you want/need
OCR or just graphics. If it's just graphics in monochrome justa but
...that's "just about" ... anything will do the job nicely, imo. If
you need the sophistaication of 64 Million colors and OCR, then I'd
concentrate on the software first, and let the hardware follow.
  
Does anyone know whether the Imagewriter/ThunderScan unit can be
adapted to the PC. I've seen (not used) that work and it's impressive.

I'm really interested in writing an OCR-type of software.  The hand scanner
is the preferred device, because the paper medium is so unweildy.  The OCR
will hav eto recognize dots in different positions on a line graph...much
simpler than recognizing a font.  There are modifiers to the values, but
they are equally simple and should be "doable".  How does the data come down
the line?  Anybody know?

Is serial the answer you wanted?

Call Byte magazine, and ask for copies of articles on scanners ;)

Thanks, mistik.  I get the feeling the transmission is SERIAL, but what are
the characteristics.  I think Byte is a good suggestion for looking.
Thanks.  MOre comments are usrely welcome. (bad day for typeing!)

If it conects to a serial port, it's ........  If it conects to a 
SCSI port, it's IIIIIIII.

(Also, keep in mind that SCSI is inherently parallel -- normal SCSI-II
is 8 bits at a time, wide SCSI-II is 16 bits, and extra-wide SCSI-II
(or whatever they call it) is 32 bits.)

  <<why couldn't "they" have stated SCSI-8, SCSI-16, SCSI-32, etc?>>
  
  <Oh, that's why, not confusing enough, gee, hate when that happens>

re #12:  I have a Marstek scanner, and it came with its own adapter.
I believe it is a proprietary interface. The scanner itself may trans-
mit a serial bit stream, but it takes the electronics on the interface
to correctly build an image from the stream.

Ah.  Do you have an address to Marstek that I could write to?  mail me if
you don't want to post it.

Hi, recent price drop from Microtek put true 600x1200 dpi flatbed
scanner + software (OCR+ImageProc) + Adaptec 16 bit SCSI card
at less than US$ 300. IMO the price will drop again at 
in the next 2 -3 months,.
Regards (AW)

Most software written to do OCR works from a standard file format. The 
assumption is that the scanner hardware will have a software driver that 
converts the scanned image to a standard. the most common format for 
scanned images is TIFF (Tag Image File Format).

there is a spec for it on the web
http://www.unix.digital.com/demos/freekit/docs/tiff/html/support.html

For image converter, you can use software from Alchemy Mindworks 
or Compushow. They recognize 30+ format. For OCR the best software 
is textbridge from XEROX.

I've just gotten a film/slide scanner, and as usual the included software
leaves a lot to be desired.

How likely is it that some better driver software is available?  This is a
USB scanner, yada yada, just how universal are the drivers for this sort of
thing?  The included driver apparently supports several different scanners
from the same manufacturer.

The scanner is a "PrimeFilm 1800i", by Pacific Image Electri.  I did download
what appears to be a newer driver, but I'll have to boot back into Windows
to try it.

(I'm not even going to worry about finding a Linux driver until maybe next
year some time, lathough it would be nice if there was one)

I don't know about USB stuff, but when it comes to SCSI and (especially)
parallel stuff, the answer to "how universal are drivers?" is "not very."
There's a standard for SCSI communication with scanners, but every
manufacturer extends it and takes other liberties, so you're usually limited
to whatever drivers the manufacturer gives you.

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