Vision Operator’s Manual (v12.0 MD) Appendix B: Color Correction Parameters • Ops 19–3
Proc Amp Color Correctors
The Proc Amp Color Corrector option provides the following parameters for video signal
correction:
• Overall, Chrominance, Luminance, Cr, and Cb Gain
• Black, Cr, and Cb Offset
• Luminance Gamma
• Hue Rotation
The graph below (Figure 19.1) illustrates a video signal with no Proc Amp adjustments applied.
The horizontal axis represents signal values before any changes are applied and the vertical axis
represents signal values after any changes are applied. The solid black line running from A to B
represents an unmodified video signal where A is the minimum signal value and B is the
maximum. You can look at any point on the line and the output value matches the input value.
This line is represented in the graphs throughout the remainder of this section to provide a
standard which serves to illustrate the effects of various Proc Amp color corrector adjustments.
Figure 19.1 Video Signal with No Proc Amp Adjustments Applied
In practice, video generating equipment have limits to the signals they produce. These limits are
represented by the Output Min and Output Max lines in the graph. Some Proc Amp color
corrector adjustments cause the video signal to be clipped. This occurs when the modifications to
the video signal result in a signal value that is outside the range that the equipment can generate.
Any further modifications to the video signal cause no further changes and it remains at the limit.
The signal is said to be clipped.
Gain
Gain represents the range of signal values present in a video signal from a lowest to a highest
point (from black to white for example). Increasing gain expands this range, while decreasing
gain compresses this range. Clipping occurs if applied gain changes cause output signal values to
fall outside the allowable range. The following graph (Figure 19.2) illustrates the general effect
of increased and decreased gain.
Input Value
Output Value
A
B
Output
Max
Input
Max
Min
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