Apple Color 1.5 - Manual (Page 202)

The outer boundary does not identify the broadcast-legal limits of video, but it does
illustrate the general range of color that’s available. For example, the following image
has illegal saturation and brightness.
If you turn on the Broadcast Safe settings, the distribution of color throughout the Y
′
C
B
C
R
color space becomes constricted.
The IPT Color Space
The IPT color space is a perceptually weighted color space, the purpose of which is to more
accurately represent the hues in an image distributed on a scale that appears uniformly
linear to your eye.
While the RGB, HSL, and Y
′
C
B
C
R
color spaces present three-dimensional analyses of the
image that are mathematically accurate, and allow you to see how the colors of an image
are transformed from one gamut to another, they don’t necessarily show the distribution
of colors as your eyes perceive them. A good example of this is a conventionally calculated
hue wheel. Notice how the green portion of the hue wheel presented below seems so
much larger than the yellow or red portion.
202 Chapter 8 Analyzing Signals Using the Video Scopes