46
S T E P 3
The Relationship Between the Tone Curveand Image Brightness
The Gamma values fall with a range of 0.01 to 10.00. A value of 1 appears as a
straight line in the graph, and if the value is any value other than one, the line on
the graph will appear curved. The relationship between the shape of the curve and
image brightness is explained below.

Gamma Value = 1

Input and output and are equal
and the curve appears as a
straight line, and the input
image is displayed on the
screen without adjustment.

Gamma Value > 1

The data bends upward over
the range of input values from
shadows to highlights, making
the adjusted image brighter in
the display.

Gamma Value < 1

The data bends downward over
the range of input values from
shadows to highlights, making
the adjusted image darker in
the display.
CAUTION
•The tone curve cannot be adjusted manually in one of the color scan
modes when ColorSync is selected because the color balance is adjusted
automatically.
•The tone curve cannot be adjusted for a black and white image because
mid-tones are shown as either black or white. To adjust the brightness of
a black and white image, use the threshold setting (p. 48).
Output
Input
➟
Output
Input
➟
Output
Input
➟