User Manual

Controls Tab
The Controls tab contains the few primary controls necessary for customizing the AutoGain
operation.
NOTE: Variations over time in the input image can cause corresponding variations in
the levels of the result. For example, if a bright object moves out of an otherwise dark
shot, the remaining scene gets suddenly brighter, as the remaining darker values get
stretched to white. This also applies to sudden depth changes when Do Z is applied;
existing objects may be pushed forward or backward when a near or far object enters
or leaves the scene.
Do Z
Select the Do Z checkbox to apply the Auto Gain effect to the Z or Depth channels. This can be
useful for matching the ranges of one Z-channel to another, or to view a float Z-channel in the
RGB values.
Range
This Range control sets the black point and white point in the image. All tonal values in the
image rescale to fit within this range.
Example
– Create a horizontal gradient with the Background node. Set one color to dark gray
(RGB Values 0.2). Set the other color to light gray (RGB Values 0.8).
– Add an Auto Gain node and set the Low value to 0.0 and the High value to 0.5. This
causes the brightest pixels to be pushed down to 0.5, and the darkest pixels get
pushed to black. The remainder of the pixel values scale between those limits.
Common Controls
Settings Tab
The Settings tab in the Inspector is also duplicated in other Color nodes. These common
controls are described in detail at the end of this chapter in “The Common Controls” section.
Brightness Contrast [BC]
The BrightnessContrast node
Brightness Contrast Node Introduction
The Brightness Contrast node adjusts the gain, brightness, contrast, gamma, and saturation of
an image. The order of the controls represents the order in which the operations are applied.
Chapter – 85 Color Nodes 1849