Epson 1640SU - Perfection Photo Scanner, Reference Manual, Page: 49 / 192

Scanning Basics
2-25
When you select a curve from the Tone Curve Name list, the
settings in the Tone Correction dialog box change accordingly.
Channels
Click an option button under channels to select the color whose
tone curve you want to adjust. When the master channel at the
top is selected, your adjustments affect all three colors. Selecting
one of the other channels allows you to adjust red, green, or blue
only.
Tone curve editor
Moving the mouse pointer into the tone curve editor causes it to
change to a finger. Use this pointer to drag any of the five points
in the curve and change its shape. The x-axis of the curve is the
brightness of the original (input values) while the y-axis is the
brightness of the scanned image (output values).
To change the tone curve back to its default, select Linear from
the Tone Curve Name list.
Output values
These are the current values for output data in accordance with
the current locations of the points inside the tone curve editor.
These values change when you drag points in the tone curve
editor, or you can enter values here to change the shape of the
tone curve. Each value can be adjusted within the range of 0 to 255.
Note:
❏
Each output value name has a check box to the left of it. Highlight
and Shadow are always selected, but you can select or clear 1/4 Tone,
Midtone, and 3/4 Tone by clicking their check boxes.
Open
Shadow 245 193 129 80 5 Lightens dark
shadows
Curve
Name Highlight 1/4
Tone Midtone 3/4
Tone Shadow Description