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Epson Perfection 4990 Manual del usuario

User's Manual

Table 1

Image types, characteristics, and resolution

Image Type

color photo

black & white photo

illustration

text/line art

color document

black & white document

Note 1: The exact criteria by which automatic mode categorizes items is difficult to determine. The descriptions shown

here are based on tests with the Model 1650 scanner. In some cases, the image preview assigned an image type other

than what was expected. However, we found that automatic mode always produced reasonably good scans.

During the preview, it is possible to interrupt the automatic scan and activate the TWAIN driver's

manual mode. Manual mode allows the user to manually control a number of image attributes

such as resolution, color balance, and image area. The use of manual mode is not recommended

for most AFHCAN installations.

Note: The settings in manual mode are complex and are beyond the

scope of this manual (refer to the Epson documentation for details).

For those not familiar with advanced scanning features, manual mode

can cause a lot of confusion, and can lead to technical difficulties or

poor quality scans. Furthermore, some combinations of manual

settings can generate huge files and may lead to system freeze-up.

Please be aware that the last scanner mode used becomes the default

mode for the next session. If someone goes into manual mode and

does not set it back to automatic mode, the next person to use the

scanner will encounter the screen for manual mode. Software running

on an AFHCAN Cart will reset the TWAIN driver to automatic mode

each time the software is restarted.

On completion of the scan, the TWAIN driver saves the file and notifies the AFHCAN software

that a scanned file has been saved. If for some reason the TWAIN driver cannot complete the

scan, the AFHCAN software will display a Scan Failed message.

There are several situations that can cause a Scan Failed message to appear in the AFHCAN

software. Some of the more obvious ones are the following:

• the scan was canceled in the TWAIN driver window

• scanner power switch is turned off or the scanner power cable is disconnected

• scanner data cable is disconnected

PUB-119 Rev B.doc

Scanner

Description

high resolution, color image

high resolution, black and white image

drawing with halftone components

mostly text with simple line art

color words and images (printed, not photo)

black & white words and images (printed, not photo)

Epson Perfection

Default

Resolution

300 dpi

150 dpi

300 dpi

150 dpi