Category : Printer + Display Graphics
Archive   : HANDSCAN.ZIP
Filename : HANDSCAN.DOC

Hand Scanners



Many hand scanners are now supported by PAINTBRUSH. Quite often
their usage with PAINTBRUSH differs quite a bit from the bundled
software that came with the hand scanner. This is because
PAINTBRUSH uses DOS Device Drivers to interface all types of
scanners, not just hand scanners. Also PAINTBRUSH was primarily
designed to support scanners that are programmable and under
the complete control of PAINTBRUSH. Because of the human
element involved with hand scanning, PAINTBRUSH must attempt to
deal with additional restrictions.

This document has been compiled to help explain and perhaps
eliminate some of the problems you might encounter. Since ZSoft
scanner device drivers work with all ZSoft scanning products
this document is of a generic nature, although PAINTBRUSH IV
Plus is presumed for the sake of simplicity.

If you find that the image produced by our hand scanner
driver is not as good as the image you can produce with the
software that was bundled with your hand scanner, then you are
advised to use that software to scan, then import the image for
editing with PAINTBRUSH.

To use a hand scanner, first install the driver as usual, making
sure that the ZSoft scanner driver comes after the EMS driver in
the CONFIG.SYS. Make sure that all parameters are setup
correctly on the command line. Most hand scanner drivers will
operate more that one type of hand scanner from the same
manufacturer.

Reboot the computer to install the driver. A message will be
displayed during the boot process, that identifies the driver,
and additional information about the hand scanner installation.
Note that the scanner driver will state what EMS is available.

Since the available hand scanners can only scan in black and
white, PAINTBRUSH should be run in a two color mode. This saves
memory, because PAINTBRUSH must allocate a scanning buffer for
each plane or color. In the case of 16 color, the scanning
buffer will take up four times as much memory as it will in a
two color mode. So if you try to scan while in color mode, you
will run out of memory four times as fast. This may not seem to
be a problem if you have plenty of EMS memory, but a 16 color
mode will generate .PCX files four times as large as necessary.
So run PBSETUP.EXE and chose an appropriate two color mode to
scan with. Remember that you can always read your .PCX files in
to a color mode later.

Now you are ready to run PAINTBRUSH. PAINTBRUSH will initialize
the scanner when the scanning option is chosen. If the driver is
not present there will be a 'Scanner Not Available' message.
Check your CONFIG.SYS file. The hand scanner light should turn
on for a second. This is to let you know that it is properly
installed at the right port address.

When PAINTBRUSH is ready for use, you can look at Statistics
under the Help window to determine what particular scanner type
the device driver is setup to operate. Some hand scanner drivers
support many different hand scanners, so these will display a
different message for each different setup. This is to confirm
that you have set the hand scanner driver up correctly for your
scanner. Choose the Scan option. You will see the dialogue box
for scanning. Some of the functions for you scanner may not be
displayed in the dialog box. This is because the controls for
these functions are on the hand scanner itself, and there is no
way for PAINTBRUSH to actually program these hand scanners for
these functions.

Make what ever adjustments you want to the hand scanner. Note
the resolution that you choose on the hand scanner must match
the setting in the dialog box. For instance, if you want a 100
DPI scan, you must set the scanner to that resolution and set
Paintbrush's dialog box as well. Mismatch of resolutions can
severely distort a hand scanner image.

The PAINTBRUSH dialog box may not show an option for Brightness
or Dithering, even if you scanner supports them. This is because
Brightness and Dither are usually set on the hand scanner
itself.

Once all of this is set, you may click on 'OK' and proceed to
the scan sizing dialog box. Here you set the size of the image
to scan. There are several things that are useful to know. Image
width is limited by the size of the scanner, but image length is
limited to available memory. Hand scanner drivers allow a
maximum of fourteen (14) inches for a scan if enough EMS is
available.

The scanning window is treated differently with hand scanners
than it is with flatbed or sheet-fed scanners. The scanning
window always starts in the upper left hand corner and is wide
as the maximum scanning width of the hand scanner. Actually you
can set the left and right margins, however if the right margin
is greater than the scan length then the driver will 'clip' the
width to the maximum scanner length. Also if the user sets the
left margin greater than the maximum width of the hand scanner,
then the driver will not be able to return any information
because the window is outside of the scanner's range.

Top margins may be set, but this is a redundant option; it is
assumed that the hand scanner will be placed at the top of the
area to scan. The bottom margin is very important because this
determines the scan length.

So to set the hand scanner window, drag the mouse down and to
the right in the window sizing box. Hit the right mouse button
to fix the size. If the width is too great the driver will
'clip' it to the maximum length. If the length is too great,
then PAINTBRUSH will return an error message.

There are two variations of error messages that relate to a
memory shortage. With only DOS memory and no EMS, PAINTBRUSH may
return an 'Image Too Big' message. If there is not enough EMS a
'Scan Open Error', will be displayed. In either event there are
two things that can be done, either scan a smaller area or
switch to a lower resolution.



** NOTE: While scanning, you will not see the image appear on
screen until AFTER the full scan has been completed **.



The successful use of hand scanners require some additional
considerations:

Hand scanners are very memory dependent. All ZSoft scanner
Device Drivers will utilize any available EMS memory, however
the drivers require LIM 4.0 or equivalent EMS drivers to work
with Windows (tm). If there is no EMS then the driver will use
the available DOS memory to scan into, or save the scanned image
to the hard disk.

Since the user provides the scanning motion with a hand scanner,
the image quality is dependent on the speed at which the hand
scanner is moved. A steady slow movement over the imaging
surface is recommended for the best scans. If a scan is too fast
the image will appear squashed, and the distance that is scanned
will be more than that chosen in the dialog box for the scanning
window.

Its easy to figure the maximum size image available under a
given resolution: Size in Bytes = DPI * Width of Scan * DPI *
Length of Scan / 8 Pels per Byte

So a 200 DPI scan, four (4) inches wide and three (3) inches log
requires:

200 * 4 * 200 * 3 / 8 = 60000 bytes or 60Kbytes



Hand scanner drivers will work without EMS, but in a restricted
manner; mainly the scanned image must be reduced in size. For
instance, on most 640 K machines, typical scanned images sizes
are:

Resolution Image SizeDOS Memory Used

200 DPI 4" X 6" 120K

300 DPI 4" X 3" 120K

400 DPI 4" X 1.5" 120K

Image quality is very dependent on scanning speed. Scanning too
fast will squash the image. Some hand scanners have a scan over
run light, that goes out if you are scanning too fast. When
scanning, you can stop scanning, release the scan switch
momentarily and the over run light will come back on.

If you are using 386MAX Version 4.06 or less, it may be
impossible to use the scanner. Qualitas has fixed the problem
in Version 4.07.

PAINTBRUSH may save buffers to the hard disk during the scan.
When the disk is accessed, scan lines can be lost, resulting in
gaps in the image. The entire scan may be scanned to Expanded
Memory and then read back as required, greatly reducing the
chance of losing scan lines.

You will find that if you do not scan when the hard disk light
is on, (ie., when the disk is being accessed) that the image
will be better.

LIMITATIONS:

THESE DRIVERS ARE GAMMA RELEASE LEVEL. THIS MEANS THAT THEY
WORKS WELL ENOUGH TO PASS OUR TESTING DEPARTMENT; HOWEVER, WITH
THE MYRIAD OF PC HARDWARE AVAILABLE ON THE MARKET TODAY, THERE
MAY BE SOME PROBLEMS REMAINING.

WE DO KNOW THAT THESE DRIVERS (VERSION 4.01) WILL PRODUCE
SEAMLESS IMAGES WITH LIM 4.0 EMS AND AN 'AT' COMPUTER, WITH THE
EXCEPTION OF NISCAN.SYS.