Microtek ScanMaker 6400XL, Справочное руководство

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Reference: The Settings Window 63
Dynamic Range tool
This tool lets you locate the lightest tone (Dmin) and the darkest tone (Dmax)
of the original in the prescan image; and then capture the full tonal range of the
final scan image without posterization.
The maximum dynamic range depends on the bit depth of the scanner model.
For example, a 12-bit per (R, G, and B) color scanner may have 3.6D in
dynamic range; where a 8-bit per color scanner will have lower dynamic range.
Dynamic range differs from scan materials as well. A piece of positive original
can have a dynamic range up to 4.0D, yet negative original or reflective material
(picture or printed document) results a dynamic range possibly equal or lower
than 2.0D. Without optimized remapping from scanner's dynamic range to the
dynamic range of the original, tonal range of the image will not be fully
captured, resulting poor contrast.
Automatic dynamic range setting determines the lightest tone (Dmin) and
darkest tone (Dmax) of the original automatically, then captures the image with
the full input tonal range of the scanner. This setting optimizes the contrast of
the output image, most useful for scanning negative films.
Note: Automatic dynamic range is not suitable for originals such as image contains
direct light sources or specular highlights such as reflections from shining metal or
bright glass surfaces, these should be kept as purely white. An automatic Dmin may
generally be placed incorrectly in specular highlights, causing other highlights and
midtones to be darkened. In addition, automatic Dmin/Dmax setting is not suitable
for low-key and high-key images.