Managing Digitization Activities · 125
http://www.lib.purdue.edu/spcol/digit/docs.html
Purdue University
one consistent size or
a %of the master
copy, depending on
size of originals)
BIT DEPTH 24 bit color** 24 bit color** 24 bit color** 24 bit color**
SECURITY Digital signature Invisible watermark with transaction
code when sending electronically
Visible
watermark
(nonintrusive)
and Invisible
watermark
N/A
STORAGE
MEDIA
Gold CDs (master
&backup copies)
&Server
Server Server Server
NOTES Unedited &
uncompressed
rarely used copy
very large file
size
Users must sign a permissions form
specifying their intended use of the
image and adhering to the Libraries
copyright and publication policies
and procedures
Should fit on
standard
monitor
reasonable file
size
Should display
quickly and give the
user a general idea of
the overall image
*Multipage documents may be stored in PDF
format **For black and white textual items, 1bit or 8 bit may be used
Scanning from negatives when possible is essential. In most cases, negatives are not available so it is important to
use a first generation print. The team has chosen to scan all images as color in order to preserve the object as
accurately as possible.
Although many formats for multi-resolution objects are available, the team chose JPEG2000. This is an open
standard format and not proprietary. The uses a non-proprietary compression scheme providing extremely fast
delivery times.
Quality Control
Dynamic range
A highly significant factor affecting image quality is the Tonal Dynamic Range – the color space that an image
occupies between pure white (255) and pure black (0). Professional TWAIN drivers and image editors such as
Photoshop can display tonal dynamic range. Reviewing histograms at the time of scanning is essential to maintain
high quality scans.
Clipping &Spiking
Clipping and spiking appear when black and white points are not set on TRUE black and white. Spiking on the
ends of the histogram usually indicates clipping. The image itself may exhibit blockage and pixelization in the
http://www.lib.purdue.edu/spcol/digit/docs.html
Purdue University
one consistent size or
a %of the master
copy, depending on
size of originals)
BIT DEPTH 24 bit color** 24 bit color** 24 bit color** 24 bit color**
SECURITY Digital signature Invisible watermark with transaction
code when sending electronically
Visible
watermark
(nonintrusive)
and Invisible
watermark
N/A
STORAGE
MEDIA
Gold CDs (master
&backup copies)
&Server
Server Server Server
NOTES Unedited &
uncompressed
rarely used copy
very large file
size
Users must sign a permissions form
specifying their intended use of the
image and adhering to the Libraries
copyright and publication policies
and procedures
Should fit on
standard
monitor
reasonable file
size
Should display
quickly and give the
user a general idea of
the overall image
*Multipage documents may be stored in PDF
format **For black and white textual items, 1bit or 8 bit may be used
Scanning from negatives when possible is essential. In most cases, negatives are not available so it is important to
use a first generation print. The team has chosen to scan all images as color in order to preserve the object as
accurately as possible.
Although many formats for multi-resolution objects are available, the team chose JPEG2000. This is an open
standard format and not proprietary. The uses a non-proprietary compression scheme providing extremely fast
delivery times.
Quality Control
Dynamic range
A highly significant factor affecting image quality is the Tonal Dynamic Range – the color space that an image
occupies between pure white (255) and pure black (0). Professional TWAIN drivers and image editors such as
Photoshop can display tonal dynamic range. Reviewing histograms at the time of scanning is essential to maintain
high quality scans.
Clipping &Spiking
Clipping and spiking appear when black and white points are not set on TRUE black and white. Spiking on the
ends of the histogram usually indicates clipping. The image itself may exhibit blockage and pixelization in the
