User Manual

Correction Tab Levels Menu
The main Correction tab is further separated into four types of correction methods: colors,
levels, histogram, and suppress. When Levels is selected from the menu, you can remap the
white and black points of an image, with a Gamma control to adjust midtones. A histogram
provides a view of the tonal distribution in the image to help guide your adjustments. The Level
method is described in detail below.
Range
Identical to the Range menu when Color is selected in the Menu, the Range menu determines
the tonal range affected by the color correction controls in this tab. The menu can be set to
Shadows, Midtones, Highlights, and Master, where Master is the default affecting the
entire image.
The selected range is maintained throughout the Colors, Levels, and Suppress sections of the
Color Corrector node.
Adjustments made to the image in the Master channel are applied to the image after any
changes made to the Highlights, Midtones, and Shadows ranges.
NOTE: The controls are independent for each color range. For example, adjusting the
Gamma control while in Shadows mode does not change or affect the value of the
Gamma control for the Highlights mode. Each control is independent and applied
separately.
Channel
This menu is used to select and display the histogram for each color channel or for the
Master channel.
Histogram Display
A histogram is a chart that represents the distribution of color values in the scene. The chart
reads from left to right, with the leftmost values representing the darkest colors in the scene
and the rightmost values representing the brightest. The more pixels in an image with the same
or similar value, the higher that portion of the chart is.
Luminance is calculated per channel; therefore, the red, green, and blue channels all have their
own histogram, and the combined result of these comprises the Master Histogram.
To scale the histogram vertically, place the mouse pointer inside the control and drag the
pointer up to zoom in or down to zoom out.
Display Selector Toolbar
The Display Selector toolbar at the top of the histogram provides a method of enabling and
disabling components of the histogram display. Hold the mouse pointer over the button to
display a tooltip that describes the button’s function.
 Input Histogram: This enables or disables the display of the input image’s histogram.
 Reference Histogram: This enables or disables the display of the reference image’s
histogram.
 Output Histogram: This enables or disables the display of the histogram from the post-
color-corrected image.
 Corrective Curve: This toggles the display of a spline used to visualize exactly how
auto color corrections applied using a reference image are affecting the image. This
can be useful when equalizing luminance between the input and reference images.
Chapter – 85 Color Nodes 1860