Setting The White Point - Nikon Scanners Software Reference Manual

The Gamma Curve Editor Dialog
(a) The original 1:1 Master Curve
Master Curve
Black Point Marker
(b) The resulting Master Curve
after setting the Black Point
Master Curve
Black Point
Figure 16.21 Setting the Black Point.
This tool can be used with any gamma curve, although it is most effective when
used with the Master gamma curve.
After the Black Point button is clicked, shown in Figure 16.22, position the
mouse cursor over the image in the preview window and select a pixel value to be used
as the darkest point in the image. This will be the Black Point, or reference point for
darkness. In addition, the pixel's location and RGB component values will be displayed,
as described in the "Marker Button" section of this manual.
Figure 16.22 The Black Point button – Macintosh and Windows.
When you decide on the pixel you want to use as the image's Black Point, clicking
the mouse forces the gamma curves to use this value as the minimum value in the pre-
view window. Any pixels darker than the black point will be set to the minimum value.
The result of this new curve is approximated in the preview window.

Setting the White Point

The White Point represents the lightest point in the image, thus serving the
reverse function of the Black Point. Like the Black Point, selection of a White Point
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Chapter 16
Software Reference for Scanners