Ross Vision - Offsets

Ops 19–4 • Appendix B: Color Correction Parameters Vision Operator’s Manual (v12.0 MD)
Figure 19.2 General Effects of Increased and Decreased Gain
The Vision switcher can perform 5 types of Proc Amp gain corrections:
• Overall Gain — Affects both chrominance and luminance video signal components
simultaneously. Increasing overall gain causes an increase in contrast while also making
colors more saturated and vivid. Decreasing overall gain causes a decrease in contrast
while desaturating colors.
• Chroma Gain — Affects both chrominance video signal components (Cr and Cb)
simultaneously. Increasing chroma gain causes the video signal colors to become
increasingly saturated and more vivid. Decreasing chroma gain desaturates color from
the video signal until it is black and white.
• Lum Gain — Affects the luminance video signal component. Increasing lum gain
expands the contrast of the video signal (i.e. bright regions get brighter and dark regions
get darker). Decreasing lum gain shrinks the contrast of the video signal (i.e. bright
regions and dark regions tend towards a middle brightness region).
• Cr Gain — Affects the Cr component of the chrominance video signal. Increasing Cr
gain causes the video signal colors to become increasingly saturated with red. Decreasing
Cr gain desaturates red from the video signal.
• Cb Gain — Affects the Cb component of the chrominance video signal. Increasing Cb
gain causes the video signal colors to become increasingly saturated with blue.
Decreasing Cb gain desaturates blue from the video signal.
Offsets
Offsets shift the video signal by a set amount. Depending on the offset applied, different parts or
all of the video signal may be affected. Clipping occurs if applied offsets cause output signal
values to fall outside the allowable range. The following graph (Figure 19.3) illustrates the
general effect of adding positive or negative offsets to a video signal.
Figure 19.3 General Effects of Increased and Decreased Offset
Input Value
Output Value
Standard
Increased Gain
Decreased Gain
A
B
Output
Max
Input
Max
Min
Input Value
Output Value
Standard
Entire Signal Offset
A Section Offset (+ and - shown)
B Section Offset (+ and - shown)
A
B
Output
Max
Input
Max
Min