Operation Manual

Tuning Utilities
124 ViewCast
Understanding the display
The waveform consists primarily of a brightness signal (called luminance) and a high-frequency
color signal (called chrominance). The luminance and chrominance added together form the
overall waveform.
The luminance signal, a series of voltages or levels, determines brightness and variations across
the picture. Each of the colors in the color bars signal has a different luminance level, and bars
arranged by level from highest to lowest (white, yellow, cyan, green, magenta, red, blue, and
black).
The chrominance signal is a sine wave. Because of this signal's high frequency, the sine wave
cycles appear to run together in most displays. However, you can see individual cycles when you
expand the display horizontally.
Color bar test signals fall into two general categories: 100% bars (full amplitude) or 75% bars
(reduced amplitude).
Note: Always use 75% bars for basic testing because 100% bars contain signal levels
that may be too high to pass through a system without distortion.
Adjust the source by adjusting the brightness and/or contrast on the capture card until it
resembles a flight of stairs (Figure 106).
Figure 106. Vectorscope with Settings to be Adjusted