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| Film
scanner test targets: To determine a scanner's resolution, we scan a test slide to determine the maximum line pairs/mm that the scanner can reproduce.
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CRITICAL
FEATURES
Scanning resolution and color accuracy are the
most important specifications to check when choosing
a scanner. The results of our resolution and color
tests are listed with each scanner on the following
pages, along with other important features such
as scanning times, density range, and color-bit
depth. We found that scanning times had improved
across the board for all models, as compared to
our last roundup. But it's hard to rate the fastest
of the bunch, since some units feature multi-sampling
technology, which improves image quality (especially
in the shadows) while adding significantly to
scan times. A related improvement has to be the
presence of IEEE1394 (Firewire) connectors on
three of the scanners tested. While not as fast
as the best SCSI connection, IEEE1394 units are
hot-swappable—they can be connected to a computer
without turning it off.
DIGITAL
DEFINITIONS
D-range:D is for density, and the D-range number
rates a scanner's ability to reproduce brightness
values from deep shadows to bright highlights.
The higher the D-range, the more detail the
scanner is capable of capturing. A good flatbed
scanner may have a 3.0 or higher D-range, while
top film scanners now boast a 3.6 D-range or
better. (Note: a 3.0-3.6 D-range corresponds
to what you'll find on a contrasty color slide.)
If the scanner has a wide D-range, the image
will show better shadow detail, without blocking
up highlights.
Bit-depth:
A scanner's ability to differentiate between
shades of gray and subtle color variations is
rated in terms of color-bit depth. Less expensive
scanners feature 24-bit color; higher-end units
offer 36-bit or even 48-bit color. Unfortunately,
not all imaging software is capable of opening
a 36-bit or 48-bit color file. But all 36- or
48-bit scanners give you the option to correct
color within the scan driver and save your images
in compatible 24-bit color.
Color
accuracy: This rating determines a scanner's
ability to accurately capture the colors found
on a color slide. For color-negative scans,
most units feature a variety of presets for
different film types. Some scanners support
color
management technologies (ColorSync on the Mac
and ICM 2.0 on the PC) and ship with factory-generated
color profiles that can be used in imaging programs
to improve color accuracy throughout the digital
workflow.
Several
of these scanners also include profiling software
and color test targets that can be used to generate
custom color profiles of the scanner. So you
can calibrate your scanner on a regularly and
compensate for color shifts that occur from
age, temperature, and humidity. We found that
scanners that came with profiling software (which
we used) did the best in our color accuracy
tests, especially with slide film.
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