Apple Color 1.0 - Manual (Page 202)

202 Chapter 9 Primary In
 Saturation: This parameter controls the saturation of the entire image. The default
value of 1 makes no change to image saturation. Reducing this value lowers the
intensity of the color of every pixel in the image; at 0 the image becomes a grayscale
monochrome image showing only the luma. Raising the saturation increases the
intensity of the color, up to a maximum value of 4.
Beware of raising image saturation too much; this can result in colors that start to
“bleed” into one another and a signal that’s illegal for broadcast.
If the Broadcast Safe settings are turned on, the legality of the image will be
protected, but you may see some flattening in particularly colorful parts of the image
that results from the chroma of the image being limited at the specified value. You
can see this in the Vectorscope by the bunching up at the edges of the graph. Even if
you’re not working on a project for video, severely oversaturated colors can cause
problems and look unprofessional.
Saturation reduced by more than half
Original image
A dramatically oversaturated image