Graphics Reference
In-Depth Information
One of the tricky things with the color wheels—or trackballs—is to figure
out which way you need to move when watching the RGB Parade wave-
form. Using hue offsets while monitoring a vectorscope is very easy. It's
almost like you're directly manipulating the image on the vectorscope
with the wheels. It's the same kind of direct manipulation and response
you get with RGB controls or curves while watching the RGB waveform.
Using the trackballs or hue offsets is one of the most universal,
hands-on ways to do color correction, and the RGB Parade waveform
is arguably the most important piece of test equipment for color cor-
rection—not counting the video monitor itself. So you really should
have a good understanding of how these two pieces of equipment work
together.
Load the “grayscale_neutral” clip into your preferred color correction
software that has hue offset wheels (or some form of “color wheel” cor-
rection). The goal here is to make the movement of the trackballs or color
wheels correspond in your brain to the resulting desired movement for
each cell in the RGB Parade waveform. This is not something that's going
to happen quickly for many people. If you are a musician, think of it like
practicing a musical instrument. You need to get the feel of this “under
your fingers.” It's a question of muscle memory that will develop over
some time. The directions should make sense, because they adhere to
the color theory that we've already discussed elsewhere. It may appear
to be backward, but if you understand what the color wheels are actually
doing, it will make more sense.
Consider pulling the shadow trackball straight toward green (mov-
ing toward the 8 o'clock position on the wheel). What do you think
should happen to the RGB Parade waveform? If you consider that pull-
ing the wheel toward green is adding green and that you are doing this
in the shadow wheel, then you should guess correctly that the green
cell will rise at the bottom and the red and blue cells will come down,
because the opposite of green is magenta, which is composed equally of
red and blue.
From that position, swing the point on the color wheel from 8 o'clock
toward 9 o'clock. Green stays the same basically and red (which is in that
basic direction) moves up and blue (which is in the opposite direction)
moves down. Swinging from 8 o'clock toward 6 o'clock raises the blue
channel while keeping green fairly even and lowering red.
Using the trackballs or hue offsets is one of the most universal,
hands-on ways to do color correction.
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