Apple Color 1.5 - Manual (Page 31)

Gamma Explained
Gamma refers to two different concepts. In a video signal, gamma refers to the nonlinear
representation of luminance in a picture displayed on a broadcast or computer monitor.
Since the eye has a nonlinear response to light (mentioned in
The Y
′
C
B
C
R
Color Model
Explained ), applying a gamma adjustment while recording an image maximizes the
perceptible recorded detail in video signals with limited bandwidth. Upon playback, a
television or monitor applies an inverted gamma function to return the image to its
“original” state.
You want to avoid unplanned gamma adjustments when sending media from Final Cut Pro
to Color. It’s important to keep track of any possible gamma adjustments that occur when
exporting or importing clips in Final Cut Pro during the editing process, so that these
adjustments are accounted for and avoided during the Final Cut Pro–to–Color roundtrip.
For more information on gamma handling in Final Cut Pro, see the Final Cut Pro 7
User Manual.
Gamma is also used to describe a nonlinear adjustment made to the distribution of
midtones in an image. For example, a gamma adjustment leaves the black point and the
white point of an image alone, but either brightens or darkens the midtones according
to the type of adjustment being made. For more information on gamma and midtones
adjustments, see
The Primary In Room .
Chroma Explained
Chroma (also referred to as chrominance) describes the color channels in your shots,
ranging from the absence of color to the maximum levels of color that can be represented.
Specific chroma values can be described using two properties, hue and saturation.
Hue
Hue describes the actual color itself, whether it’s red or green or yellow. Hue is measured
as an angle on a color wheel.
31 Chapter 1 Color Correction Basics