Specifications

This integration enables a Photoshop user, for example, to choose a TWAIN device as an image source,
start the device (a scanner, for example), scan the image, and have the resulting image appear in the
Photoshop window for editing—all without the need to close down or reopen Photoshop. TWAIN also
opens the door to direct scanner support in word processing and page layout programs, as well as in
the traditional graphics-editing, photo-editing, and OCR programs.
Because TWAIN provides a standardized interface at the application level, creators of photo editors,
OCR programs, and other typical scanner-driven programs no longer need to write customized drivers
for the increasing numbers of scanners on the market.
TWAIN also minimizes the chances of scanners becoming outdated due to a lack of software support.
Because all the scanner manufacturer has to do is write a single TWAIN driver for each operating sys-
tem/scanner combination, older scanners can be supported for several years.
Image and Scanner Interface Specification
Image and Scanner Interface Specification (ISIS), created and controlled by Pixel Translations, is
another popular imaging-software interface standard. Unlike TWAIN, ISIS is designed to provide sup-
port for not only image acquisition, but also image processing and image handling with languages
such as Java and Visual Basic OCXs and applications created with these languages.
Pixel Translations provides free toolkits enabling vendors to create ISIS-compliant drivers and also
supplies customized drivers to many major scanner vendors. If your scanner provides both ISIS and
TWAIN support, try each of them to see which provides you with better performance and features.
Because TWAIN, despite its more limited role, is more popular than ISIS, Pixel Translations will be
releasing drivers that enable any ISIS application to use TWAIN drivers.
If your software lists a File option such as Acquire or Import, your application probably supports
TWAIN or ISIS scanner control. If you have multiple TWAIN or ISIS devices, you’ll normally have a
menu option to Select Source, enabling you to choose which scanner or other digital source to use for
image acquisition.
Getting the Most from Your Scanner’s Hardware
Configuration
1. Use the fastest interface your scanner offers.If your scanner offers either SCSI and USB or SCSI and
parallel, it’s worth the extra time and expense (both minimal with Windows 9x) to buy and
install a SCSI interface card (some scanners come with the appropriate SCSI card). SCSI is the
fastest of the three major interfaces, and speed is a critical factor in scanning, especially with
large originals and high scanning resolutions. If you’re already using a SCSI card for any other
device, you should be able to attach your scanner to it if it’s an Adaptec ASPI-compliant SCSI
card and scanner. If your system has an IEEE-1394 port and you can afford to spend more
money, get an IEEE-1394 scanner for even better performance than with SCSI.
2. Set your LPT port for best performance if you use a parallel-port scanner. Generally, bidirectional, EPP,
or ECP/EPP modes are recommended for scanners that use parallel ports. (Check your documen-
tation for details.) As you saw with other parallel-port devices, using the fastest possible settings
that are compatible with all LPT devices you use is the best route to follow.
3. Get SCSI right. Although SCSI interfacing is one of the fastest interfaces for scanners and many
other peripherals, it offers several challenges.
If your scanner will be added to a daisy-chain of existing SCSI devices, you might need to pur-
chase a different cable from the one that came with your scanner.