User`s manual

Reference: The Advanced Image Correction tools 87
Gradation tool (LCH color mode)
The Gradation tool lets you adjust the midtones (the mid-level grays) of the
lightness channel ā€œLā€ of an image without altering the color itself. This is
because even with changes to the luminance or lightness value, the chroma and
hue values are kept constant.
To prevent color images from losing saturation when adjusting the lightness,
ScanWizard Pro provides a Saturation Range option. With this option, colors
outside of a given chroma range are not affected by the manipulation of the
gradation curve.
.
How to read the curve
The Curve shows the relationship
of the brightness changes across
the middle pixels between the
resulting image and the original.
When you open the Curves dialog
box, the line on the graph is
diagonal because the Input and
Output values are the same.
When the curve is moved up or
down, the relationship between
input value and output value
changes accordingly.
• In areas where the curve is
moved down, pixels in that
portion of the image are
darkened.
• In areas where the curve is
moved up, pixels in that portion
of the image are lightened.
Contrast in an image can be seen
by the angle of the line. The
steeper the slope, the higher the
contrast. The closer the line is to
horizontal, the lower the contrast.
Original curve
Modified curve