Proc Amp and RGB Color Corrector Options
Digital Proc Amps
A digital proc amp takes an incoming video signal, and allows you to modify it in the Y, R-Y, B-Y format (Y = Luminance, R-Y and B-Y are the red and blue components). This is the signal format inside an HD/SDI signal stream.
Most proc amp controls adjust the luminance signal (Y signal), although some rudimentary color modifications are possible.
The Ross Video Synergy MD proc amp has the ability to add offsets as well as apply gain to the luminance signal. Gain can be applied linearly, or by changing the gamma response of the luminance signal.
The chroma values (R-Y and B-Y) can have a hue rotation and a gain applied.
Proc amps are useful for correcting analog level and chroma phase errors caused by system timing errors, transmission losses, and incorrect equipment calibration.
Digital RGB Color Correctors
A digital RGB color corrector takes an incoming Y, R-Y, B-Y video signal, converts it to RGB, makes modifications to the RGB components, and then converts the signal back to Y, R-Y, B-Y.
Available adjustments to the RGB components are the same as those for the luminance signal in the proc amp. Each RGB component can be adjusted individually. Offsets can be added, and gain can be applied either linearly or by changing the gamma response of that component.
RGB color correction is useful for correcting lighting temperature variations and differences in camera calibration, or for adding creative effects, which can be stored to a memory and used to perform Effects Dissolves.
Gamma Correction
Gamma changes control the overall brightness of an image. A linear gain takes the incoming signal value, multiplies it by an amount, and returns that new value. A linear gain appears as a straight line on a graph. A gamma change on a signal makes the input to output conversion of the signal look like a curve. Refer to the diagram below.
How are these options sold in the MD/X switcher?
There is one option for proc amps (SxMD/X-012) and one option for RGB color correctors (SxMD/X-013) per switcher. The Proc Amps option consists of 5 proc amps per full MLE. The RGB Color Correction option consists of 5 colour correctors per full MLE. These are two independent software options that are enabled switcher-wide through the Software Options menu in the switcher.
How do I get control of them?
Four each of the proc amps and color correctors sit on the Background, Preset, Key 1 and Key 2 buses. The fifth one is used for modifying Aux Bus video. Double pressing a crosspoint button brings up the Video Correction menu. This menu gives you access to proc amp and RGB color correction settings, and allows you to modify these settings “per input” or “per bus”.
In input mode, each input on the switcher has its proc amp and RGB color correction settings saved. When that input is used, those settings are used. So, although the proc amps and color correctors sit on the buses, the values that are used are input values, and those same values are applied each time the input is used on any of the switcher buses.
In bus mode, the same proc amp and RGB color correction values are used for all inputs on a bus and each bus may have different values. These values are also stored with switcher memories so special effects can be setup and recalled.
When an input has corrections applied to it and that input is selected in bus mode, the input will have both sets of values applied to it. First, the input will be corrected per its input settings, and then the bus settings will be applied.
How do I correct an output to, for instance, feed a plasma monitor?
Every MLE that the switcher has installed can correct one Aux Bus output. Therefore, a Synergy 3 MD-X switcher can correct 3 Aux Buses. The Aux Buses that are corrected are programmed in installation.