Extra Information

Chapter 12: Tuning Utilities
96 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 that you see in Figure 154 by adjusting the brightness and/or contrast on the
capture card until it resembles a flight of stairs.
Figure 154. Vectorscope with Settings to be Adjusted