of processing steps follow scanning. Such procedures may occur at any
point in the digitization chain, from immediately after scanning to just
prior to delivery to end-users. These may be customized modifications
that affect only certain files, or mass, automated processing of all files
(batch processing). They may be one-time operations or done repeatedly
on an as-needed basis.
of file/image processing operations:
Editing, touch-up, enhancementthis includes steps such as descreening,
despeckling, deskewing, sharpening, use of custom filters, and bit-depth
adjustment. In some cases, the scanning software performs these steps.
In others, separate image-editing tools (e.g., Adobe Photoshop, Corel
Photo-Paint, ImageMagick) are utilized.
Compressionsometimes carried out by dedicated scanner firmware
or dedicated hardware in the computer. Compression can also be a software-only
operation though dedicated hardware is faster and should be considered
when creating very large files or very large numbers of files.
File format conversionthe original scan may not be in a format
suitable for all intended uses, thus requiring conversion. See Presentation.
Scalingit's likely that scans captured at high resolution will
not be suitable for on-screen display. Scaling (that is, resolution
reduction through bit disposal) is often necessary in order to create
images for Web delivery. See Presentation.
OCR (optical character recognition)conversion of scanned text to machine-readable text that
can be searched or indexed.
of text that helps describe, track, organize, or maintain an image.
In some cases, image processing can be accommodated in the scanning workstation,
especially if each image is checked as it's created. In the case of "on-the-fly"
operations such as image scaling done just prior to delivery, image processing
usually takes place on the image server.
operations may call for a separate computer. Image editing, especially
for uncompressed 24-bit color images, requires large amounts of RAM and
video memory. To work most efficiently, image editors require RAM several
times the uncompressed size of the file being edited. A large, high-resolution
monitor is also needed.
processing steps that may be carried out on every file (e.g. OCR, format
conversion, deskewing) can be extremely CPU intensive. Batch processing
requires a fast processor, lots of RAM, fast storage subsystems, and rapid
and efficient routing of data within the system. These characteristics
are more often found on multi-user systems. In particular, Unix systems,
with their inherent batch processing capabilities, are well-suited for
these kinds of tasks, though computers running Linux or Windows 2000 Professional or XP Professional may also be suitable.