Scanner questions, and what is TWAIN?
Evan Leibovitch
presently looking for two scanners; a flatbed (preferably 600 to 800dpi)
and one that reads right off 35mm negatives.
Some questions:
1) If what I want to scan is rarely wider than four inches, is a handheld
scanner adequate from the angle of quality? I've seen ads for 800dpi
colour handhelds, and I wonder if these things can really do something
that fine when they're dependent on how steady your hand is.
2) While a number of the scanners are SCSI devices, it seems that not
all of them can be just plugged into my system's Adaptec 1542 and
seen by the software. Some, like the Microtek, come with their own
SCSI host adapters, and I'd prefer to reduce the redundancy. Some
claim conformance to something called TWAIN which I'd never heard of
before; what is this?
3) Can someone offer a comparison of the Nikon Coolscan and Microtek 35t?
My main criteria is speed, quality, and flexibility of interfaces. I
know the Microtek has slightly less resolution than the Coolscan, but
that it's also faster and only two-thirds the price.
4) Has anyone written a Unix driver for *any* SCSI scanner, whether
freeware or commercial?
5) Are there any potential difficulties for a system with *both* a
flatbed *and* a 35mm scanner hooked up to the same SCSI host?
Thanks.
--
Evan Leibovitch, Sound Software Ltd., located in beautiful Brampton, Ontario
ev...@telly.on.ca / uunet!utzoo!telly!evan / (416) 452-0504
"It costs a lot of money to look as cheap as I do" -- Dolly Parton
Vassilis Prevelakis
>I'm getting a bit confused about the range of scanners out there.
>Some questions:
>2) While a number of the scanners are SCSI devices, it seems that not
> all of them can be just plugged into my system's Adaptec 1542 and
> seen by the software.
You need a driver thats capable with working with both the SCSI host adaptor
and the scanner. Since scanner interfaces are not standardised (like they
are for CD-ROMS and disks) its unlikely you'll find such a driver.
Also some scanners utilize the SCSI bus in a most wastefull way since
they know that they are likely to be the only customers for that bus.
So if you plug them along a disk drive your disk I/O will suffer when
you use the scanner.
> claim conformance to something called TWAIN which I'd never heard of
> before; what is this?
TWAIN is both a protocol and an API. Together they define how applicatios
developers can acquire raster data directly into their applications without
requiring the user to switch out of that application. Currently it is
supported on Macs and MS/Windows.
>4) Has anyone written a Unix driver for *any* SCSI scanner, whether
> freeware or commercial?
I would be very willing to write a driver for an HP IIp scanner for
386BSD Unix if only I could get my hands on some info on the SCSI
protocol used by that scanner. So far all I could get
from HP was the protocol to their DOS device driver. I tried to talk
with their Athens technical support but they brushed me off. First
they claimed that the info I requested did not exist (gave me two
manual order numbers which turned out to be the manuals shipped
with the scanner -- i.e. no technical info) and then they refused to talk
to me saying that I MUST talk with the dealer who sold me the machine.
Finally I got the fax number of an HP support center in Amsterdam and
I ordered the developers kit for the Scanjet. This contains NO info
on the SCSI protocol and I have lost all hope with the Athens support centre.
So...
Using a freely available Sun RPC implementation (and NFS server)
plus the Waterloo TCP kit, I wrote a couple of RPC routines that enable
a program on the Unix host to control the scanner on the PC (running DOS).
When I get a decent ethernet card for the PC, I'll post some speed
figures.
>5) Are there any potential difficulties for a system with *both* a
> flatbed *and* a 35mm scanner hooked up to the same SCSI host?
I think that the X-Ray scanner corp has a scanner (the XRS Omnimedia 6C)
that can scan paper, transparencies and film. Their phone number
is (310) 214 1900 and they are in California. I got this info from
a BYTE (Jul.92) scanner review so I have NO experience with this machine
or the company.
On the other hand I don't think you'll get the scanner software to use the
same host adapter so you'll be OK:-)
**vp
-----------------------------------
Vassilis Prevelakis | v...@csi.forth.gr
Thoukididou 10A | old style address:
Plaka, Athens 105 58 | ...!mcvax!ariadne!vp
GREECE |
Tel. +30 1 32 32 867 | FAX +30 1 72 24 603
Neil Gould
In a previous article, ev...@telly.on.ca (Evan Leibovitch) says:
>I'm getting a bit confused about the range of scanners out there. We are
>presently looking for two scanners; a flatbed (preferably 600 to 800dpi)
>and one that reads right off 35mm negatives.
>
There are a few general "pointers" to consider about scanners. First, about
the choice between reflective (flatbed) scanners and transparency (slide)
scanners. If most work that you will be doing is scanning 35mm slides, as
would be the case in art departments which log and process photos, then it
will be necessary to have a scanner to handle slides. These scanners are
not able to work with reflective art, OCR, etc. The reverse is true for
flatbeds, though there are a couple of units that offer attachments for
reading transparencies.
Another concern that you mentioned was the redundancy of having two SCSI
interfaces in the system, as opposed to running the scanner off of the
primary host. This concern is academic, and has no impact on the system,
aside from losing a slot. The units use different system addresses, and
as such, don't interfere with one another. On the other hand, if you were
to go to the trouble to get a scanner with a standard SCSI interface to
attach to your existing SCSI host board, then you would be faced with
writing your own interface software to access the scanner -- not a great
use of one's time, IMHO. Far less painless to set up the scanner as de-
signed and run the software packages that are already existing.
TWAIN is a "generic" interface method of accessing peripherals. It is a
standard set of "handles" which software can read/write to on one end,
and the manufacturer can adapt on the peripheral side. This supposedly
increases device independence and makes it easier to support a wider
variety of peripherals from a particular application. This may be fine
for undemanding use, but the TWAIN drivers that I have lack the amount
of control over the scanner's operations that a specific scanner driver
has.
--
neil gould + aa...@cleveland.freenet.edu
electronic media producer + Terra Tu A\V
SysOp: Video Arts Department; Co-SIGop - Audio Arts SIG
Pond Scum
>4) Has anyone written a Unix driver for *any* SCSI scanner, whether
> freeware or commercial?
I've written SCSI drivers under Solaris 1.x and 2.x for the following
scanners:
Dainippon Screen ISC-2010, SG-618, SG-737, SG-747, DT-S1015 (plus a few
other compatible models I've not actually tested)
Canon CJ10 (scanning half of a color copier)
Don't bother asking if you can have the source.
-Jonathan h...@island.COM
Richard Man
I just bought a HP ScanJet IIC flatbed color scanner and played with a
Mustek one, here's what I know:
In article <CBpLz...@telly.on.ca>, ev...@telly.on.ca (Evan Leibovitch) writes:
> I'm getting a bit confused about the range of scanners out there. We are
> presently looking for two scanners; a flatbed (preferably 600 to 800dpi)
> and one that reads right off 35mm negatives.
>
> Some questions:
> ...
>
> 2) While a number of the scanners are SCSI devices, it seems that not
> all of them can be just plugged into my system's Adaptec 1542 and
> seen by the software. Some, like the Microtek, come with their own
> SCSI host adapters, and I'd prefer to reduce the redundancy. Some
> claim conformance to something called TWAIN which I'd never heard of
> before; what is this?
Both the Mustek and the HP come with their own little SCSI cards and the
scanners will only work with their respective cards. They do coexist with
my 1542 OK though.
TWAIN is some sort of scanner protocal standard that let a TWAIN compilance
program to use your TWAIN compliance scanner without the program to supply
a specific driver for your scanner. Most high powered image processing and
paint programs support TWAIN scanners.
>
> 3) Can someone offer a comparison of the Nikon Coolscan and Microtek 35t?
> My main criteria is speed, quality, and flexibility of interfaces. I
> know the Microtek has slightly less resolution than the Coolscan, but
> that it's also faster and only two-thirds the price.
If your main interest is slide, then get a slide scanner like the Nikon.
You can always take a slide of your other subjects ;-)
>
> 4) Has anyone written a Unix driver for *any* SCSI scanner, whether
> freeware or commercial?
>
> 5) Are there any potential difficulties for a system with *both* a
> flatbed *and* a 35mm scanner hooked up to the same SCSI host?
>
I suspect each scanner has its own SCSI cards so as long as they don't use
the sames address, it should be OK.
> Thanks.
>
--
/(o\ Small Rovers // Richard F. Man
\o)/ Big Dreams // m...@zko.dec.com
Bob Gann
>> all of them can be just plugged into my system's Adaptec 1542 and
>> seen by the software.
>
>and the scanner. Since scanner interfaces are not standardised (like they
This is changing. More and more scanners are able to use 'industry standard'
cards like ASPI or CAM based cards.
For example, HP GHC has an ASPI/CAM compliant driver for the
HP ScanJet IIc and ScanJet IIp. The driver is (or will be soon)
avaliable on Compuserve. (Since I don't have access to Compuserve
I cannot comment on whether or not it is avaliable yet. There is
some time between when it is posted and when it 'appears').
It allows the IIc or IIp to be put on an ASPI card like your
adaptec 1452 card.
>>5) Are there any potential difficulties for a system with *both* a
>> flatbed *and* a 35mm scanner hooked up to the same SCSI host?
Depends on the drivers. I have connected multiple scanners of differnt
type and manufacture to one SCSI card. I have also installed
several SCSI cards to get to multiple scanners that did not work
on standard cards. Sometimes it works well, sometimes poorly.
>I'm getting a bit confused about the range of scanners out there. We are
>presently looking for two scanners; a flatbed (preferably 600 to 800dpi)
>and one that reads right off 35mm negatives.
You need to evaluate carefully, what you want from the scanners.
For instance, a 600 or 800 dpi flatbed does not have the resolution
or pixel depth to do more than 'For Position Only' scans of a 35mm
slide. So, you are correct in assuming you need a 35mm slide scanner.
AND for the vast majority of reflective art and OCR, you don't
need this must a resolution (600dpi and above). If you are doing fine
lineart (1 bit/pixel drawings) at enlarged sizes, higher resolution may
be an advantage. I say may, because just because a scanner has a high
optical SAMPLING RATE (guzillion dpi) does not mean it has high optical
RESOLUTION, or high quality scaling abilities. Some scanner can
introduce lots of ugly scaling artifacts if used improperly (i.e.,
scanning at a 'bad' resolution). Artifacts can include line dropping,
pixel replication, etc.
>TWAIN is a "generic" interface method of accessing peripherals. It is a
>standard set of "handles" which software can read/write to on one end,
>and the manufacturer can adapt on the peripheral side. This supposedly
>increases device independence and makes it easier to support a wider
>variety of peripherals from a particular application. This may be fine
>for undemanding use, but the TWAIN drivers that I have lack the amount
>of control over the scanner's operations that a specific scanner driver
>has.
TWAIN (Toolkit Without An Interesting Name), is a standard interface
protocol that allows end user app's to access many scanners (and other
devices some day). The quality of the 'Twain' driver depends on how
much time and effort the scanner manufacturer put into it as well
as how well the app developer implemented it in their application.
This is one of the disadvatages. A poor implementation of TWAIN
can be hell to use.
On the other hand, becuase an app developer doesn't need to write
driver interfaces to lots of scanners, just to TWAIN, you will
see many more apps directly supporting a scanner than before.
Also, if the scanner developer does a good job, they can provide
a good interface to their scanner and make that good interface
avaliable to many more people.
One of the advantages of Twain is it provides a common interface to
a scanner from many Apps. For instance, no matter what application
you are in, if you 'Aquire' and image via Twain from an HP scanner
you will get the same scanner interface.
The way TWAIN works is (typically) you pick 'File/Acquire' in your
end use app, the scanning application comes up and when you do
your final scan, the image is automatically placed in you app.
I say typically because some apps don't do this so well.
>> 4) Has anyone written a Unix driver for *any* SCSI scanner, whether
>> freeware or commercial?
The HP ScanJet IIc is avaliable on HP-UX workstations.
Bob Gann
HP GHC