GRASS VALLEY zodiak, User Manual

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Zodiak User Manual 297
M/E Menus
The Proc Amp Chroma parameter group can modify the gain and offset for
individual chroma components Cb and Cr. The range, nominal values, and
units for these controls are shown in
Table 7 :
Two sets of gain controls exist for chroma. One is an overall gain, found on
the Proc Amp Luma menu, and the other set is the individual Cb and Cr
gain controls found on the Proc Amp Chroma menu. The overall gain is the
average of the Cb and Cr gain. When the overall chroma gain is adjusted,
the Cb and Cr values both change by the incremental amount of the overall
gain change.
Proc Amp Transfer Function Graphics Detailed Description
Lum:
The Luma figure is modeled after a waveform monitor that displays a lumi-
nance ramp signal that has been modified by the proc amp. The horizontal
scale of the graph corresponds to the input luminance level to the proc
amp, and the vertical scale corresponds to the output level from the proc
amp. The scope trace starts at the black level in the lower left and ramps lin-
early to the white level at upper right. The dotted graticule lines signify the
nominal black to white range. The solid graticule lines mark the absolute
limits of the graph. The vertical scale is such that zero is at the black dotted
line, 100 IRE is at the white dotted line.
Luminance gain is represented by the slope of the trace. At gain zero, the
line is flat and level. Increasing the gain changes the angle of the trace. If
the gain is adjusted high enough for the trace to exceed the absolute vertical
limits, the line goes horizontal to represent clipping by the limiters in the
proc amp.
Luminance offset (black level) moves the trace up and down without
changing its slope.
Chroma:
The Chroma figure has a round screen modeled after a vectorscope. The
oval trace displays what would appear if the vectorscope were fed a
chroma key test signal with continuous hue changes and constant satura-
tion that has been modified by the proc amp. The vertical axis of the oval
corresponds to Cr gain, and the horizontal axis represents Cb gain. The
Table 7. Proc Amp Chroma Parameters
Control Minimum Maximum Nominal Units
Cb Gain 0 200 100
%
Cb Offset -100 100 0
Cr Gain 0 200 100
Cr Offset -100 100 0