Apple Final Cut Pro 5 - Manual (Page 1205)

418 Part II Project Interchange
Measuring and Evaluating Video
Before you can effectively perform color correction using the Final Cut Pro color
correction features, you need to understand the basics of what makes up the image of
a video clip.
A video clip’s image can be divided into two components, luma (luminance) and
chroma (chrominance). Together, these two components make up the picture that you
see when you play back your video. As you begin to learn how to use Final Cut Pro
scopes and color correction filters together to manipulate the look of your clips, it is
important to understand exactly what these components are.
Luma (Luminance)
Luma (also referred to as luminance) describes the image intensity of a video clip, from
absolute black, through the distribution of gray tones, all the way up to the brightest
white. Luma is completely separate from the color of your clip. In fact, if you viewed the
luma of a video clip by itself, you would see a grayscale image completely devoid of color.
Luma is measured by Final Cut Pro as a digital percentage from 0 to 100, where 0
represents absolute black and 100 represents absolute white. Final Cut Pro also allows
you to see super-white levels (levels from 101 to 109 percent) if they exist in your clip.
While super-white video levels are not considered to be broadcast safe, many
consumer camcorders record video at these levels anyway.
Note: In analog video, luma is measured in IRE. On the IRE scale, NTSC black is 7.5 IRE,
but the level of black in PAL or NTSC in Japan is 0. These IRE measurements are
irrelevant in Final Cut Pro because it deals only with the digital signal that exists in your
computer as a straight percentage from 0 to 100 for NTSC and PAL. For more
information, see Volume I, Chapter 23, “Using Color Bars for Video Calibration.”
Black
0% luminance 100% 109%
White
Superwhite