Chapter 13 - Contrast, Brightness And Color Balance; The Exposure Controls; Automatic Exposure - Nikon Scanners Software Reference Manual

Chapter 13
Contrast, Brightness and Color Balance

The Exposure Controls

The Nikon Scanner plug-in provides a great deal of automatic and manual con-
trol over a scan's contrast, brightness, and color balance. Even more accurate control
can be achieved using the Gamma Curve Editor, discussed in Chapters Fifteen and
Sixteen.
The typical scanning operation involves performing an autoexposure before the
preview scan, then implementing minor modifications through the manual controls.
The results of the autoexposure settings are seen in the original preview scan.
Changes to the manual contrast, brightness, and color balance controls will be reflected
in the preview window image after a short pause. These changes are approximations
only. These manual controls have a range of 25 to 100 for Coolscan, and 0 to 255 for
LS-3510AF. Keep in mind that there is a limited range in which changes to these con-
trols will be reflected accurately in the preview image.
The best application of these controls is to greatly alter the densities and color bal-
ance of a scan. For example, if an image is too green, the Green exposure for a color
positive can be decreased. Another way to counteract the overall green cast is to increase
the Blue and Red exposures by equal amounts. Equal amounts of Blue and Red are
equivalent to the same amount of Magenta, which is the complimentary or opposite
color to Green, and will neutralize it.
Adding to any value when scanning positives will shift the color in that direction.
!
When scanning negatives, adding to the value removes that color.

Automatic Exposure

The autoexposure operation is a powerful tool. All it requires of you is to make
sure that the film is in place. After the scanner analyzes the entire area of the film, the
resulting values will be used to center the contrast, brightness, and red, green and blue
exposures. These values are never seen by the user since they are not reported to the
user interface. The ranges provided for these parameters are based upon the results of
the autoexposure operation.
It is strongly recommended that you allow the scanner to perform an autoexpo-
sure each time it previews a new slide since the autoexposure values stored for a badly-
exposed slide will prevent a normally-exposed slide from being scanned properly. The
scanner will store the results of this autoexposure calculation. As long as this film
remains in the scanner, these autoexposure settings will remain relevant. As long as the
Software Reference for Scanners
Contrast, Brightness and Color Balance
Page 119