Curve Tool; How To Read The Curve - Microtek ScanMaker 35T Plus User Manual

Curve tool

Usage
To control the mid-
tones, or mid-level
grays, of an image.

How to Read the Curve

Original curve: Straight
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.
The x axis of the graph represents the original
brightness values of the pixels, from 0 to 255;
the y axis represents the new brightness
values. Clicking on the diagonal line then plots
a point that can be adjusted.
62 Microtek Scanner User's Guide (PC version)
The Curve tool lets you control the gamma, which measures the intensity
affecting the mid-level grays (midtones) of an image. Adjusting the gamma lets
you change the values of the middle range of gray tones without dramatically
altering the shadows and highlights.
In many ways, the Curve tool gives you the most control for adjusting an
image's values, but novice users may take some time to master its intricacies.
The Curve tool applies to grayscale and color images and is not available for
use with line art or halftone scan modes.
diagonal line
Modified curve with
points moved up
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.