User`s guide

5-46 Microtek ScanWizard 5 User's Guide (Macintosh version)
Tone Curve
The Tone Curve tool lets you adjust the tonal range of an image. However, instead of making
adjustments using just three variables (highlights, shadows, and midtones), you can adjust any point
along the 0-to-255 scale (for 8-bit images; 0-to 4096 scale for 12-bit images). The Tone Curve tool
applies to grayscale and all color images and is not available for line art or halftone scan modes.
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.
Modified curve
Original curve