Solving Luminance and Color Space Problems

Luminance and the range of possible color values for video frames are two areas of digital video that confuse everyone at some point or other. In addition to keeping track of the analog standards, there are several digital standards that are easy to confuse. Also, the world of HDTV is upon us, and it too has its own specifications for how to handle luminance and color.

The relatively common issues associated with luminance and color when working in FCP mostly have to do with mismatches between luminance ranges and how it is handled when FCP works with the three primary color spaces used in digital video production.

Luminance and Color Space Problems at a Glance
Type of Problem	Symptom	Possible Cause	Solution
Clipping	#1: Areas of flat and gray footage	High luminance levels	Avoid luminance levels above 100 IRE and use color correction in FCP; page 777
	#2: Black isn't a true black	Black level is too high	Set true black levels to 0 IRE; page 779
Luma and chroma clamping	#1: Footage dims	Illegal chroma levels	Keep luminance level below 100 IRE in sequences requiring RGB rendering; page 781
	#2: Graphics are brighter than highlights	Luminance levels don't match YUV's range	Match the range using either White or Superwhite processing options; page 784
Color space differences	#1: Banding and striping in rendered video frames	8-bit system can't match enough colors	Use a higher bit-depth codec in post-production; page 785
	#2: Video output differs from onscreen view	Color space is more limited on the output device than on the computer monitor	View video on a video monitor as well as a computer monitor; page 787