Epson Perfection 4990 User Manual - Page 8

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Epson Perfection 4990 User Manual
User's Manual
The scanners have a variety of buttons on their front panels. None of these buttons interact with
the AFHCAN software, so they are not described here. Model 1650 does not have a power
switch, but the other three models do. As installed on the AFHCAN Cart, the scanner power
switch is not readily accessible. It is the standard practice on the AFHCAN installation to leave
the scanner power button on at all times and to control power to the scanner via the Cart's main
power switch. This power distribution strategy applies to most other devices on the Cart. For
exceptions, refer to device-specific modules in this binder for details.

1.1.1 Functional Description

The scanner is used to scan paper documents, photographs, or other items into a case. The
AFHCAN software activates a TWAIN driver, which is software that comes with the scanner.
The TWAIN driver controls the operation of the scanner.
The AFHCAN software and the TWAIN driver interact differently depending on which scan
mode is selected. The AFHCAN software offers two scan modes:
• black and white (
Scan
• color (
Scan Color
In black and white mode (
in black and white. Each pixel is forced to be either white or black (in other words, shades of
gray are lost). This is useful when scanning black and white forms or other documents where
high contrast is a plus. The downside is that if there are items which are lightly shaded, those
items may be dropped, and the overall image resolution may appear to be diminished. In
mode, a small window appears indicating that a scan is underway.
PNG image format.
In the
Scan Color
mode, the TWAIN software performs the following steps:
• previews the image to determine the type of image, image area, and image characteristics
• automatically adjusts the image resolution, size, and other attributes
• scans the image and saves it in a JPG image file format
• sends the image file to the AFHCAN software for inclusion in a case
When running on a Cart, the software resets the TWAIN driver to factory defaults each time the
AFHCAN software is started. This places the TWAIN driver in automatic mode.
Note: When the software is running on a PC workstation, the reset
does not take place, which means the TWAIN driver will open in the
same mode and with the same settings that were in effect when the
software was last used.
In automatic mode, the preview is analyzed to determine the type of image, the image area, and
any optimal settings. The TWAIN software distinguishes the types of images listed in Table 1.
2
The term TWAIN refers to software that fits between the user application and a device (scanner, camera,
etc.) TWAIN drivers make it easier to standardize the integration and control of various devices on a
computer system. For more information on TWAIN, go to www.twain.org.
PUB-119 Rev B.doc
Scanner
button)
button)
Scan
mode), the AFHCAN software directs the TWAIN driver to scan
2
Epson Perfection
Scan
Scan
mode saves files in a
2