Primary Color Correction: Color Manipulation Tools - The Art and Technique of Digital Color Correction - page 143

(a) (b)

Fig. 4.57 Tektronix WVR7100 displays of both the balanced ChromaDuMonde chart (a) and the chart with a warm white balance (b).

at a 5x vertical gain. You can see that the black levels of all the red and
green channels are elevated somewhat. Looking at the composite wave-
form display in the upper right corner, you can tell that there is some kind
of color cast, because of the excursion in the trace for each chip chart.
Compare it to the tight, well-defined steps of the X in the upper right
scope of Figure 4.57 a . The vectorscope shows the red color cast because
the color chips are all pushed up toward the red vector instead of being
evenly distributed around the center of the scope.
For this tutorial, our main focus will be the standard RGB Parade
waveform display because it will match up very nicely with the specific
red, green, and blue sliders or numerical entry controls.
The controls in the Advanced Tab of Color's Primary In room are
actually laid out in the order you should use them: with lift first, gain
next, and gamma last. Watching the RGB Parade waveform, bring the
red, green, and blue lift down until the center black chip rests on the
0IRE line. Remember the focusing analogy and bring the level only low
enough to get a good clean black without clipping the signal or creating
an illegal black level. The center black chip in the blue channel reads
much higher than the darkest chip to the left. In the red and green
channels, the lowest chip is the center chip. We may have to determine
which chip we try to put at 0 for the blue channel. For now, we'll put
the center chip for the blue channel at 0. Remember, once the relative
positions of various parts of the lower part of the trace start to change,
you need to stop, because that is showing clipping. See Figure 4.58 .
Next are the gain controls. Bring them up so that the brightest part of
the white chip is at 100IRE. Note that the chart is not quite evenly lit, so
the left side of the chart is slightly brighter than the right side of the chart.