Graphics Reference
In-Depth Information
most color correction applications), histograms (available in some color
correction applications), and Luma Range view (available in a few color
correction applications). Also, some applications such as Final Cut Pro
can superimpose zebra patterns or warning symbols on video that has
levels that are near or in excess of legal limits. Avid products have a simi-
lar warning system for illegal and out-of-gamut video levels. Tektronix
scopes can also do this, with a setting called “Bright-up” displays.
Eyedropper tools (
Figure 1.18
) are a great way to look at a very spe-
cific part of the picture. You simply select the tool and click or drag to an
area of your picture that you want to analyze, and then you use the same
basic skills for balancing color on an RGB Parade waveform monitor.
The goal is to get the levels—numerical, in this case—to match across all
three color channels for any part of the image where you want a neutral
balance. Be careful, because if you're analyzing only a single pixel, you
may be looking at noise instead of the actual color. Move the eyedropper
around a little to get a sense of the surrounding pixels. Also, eyedrop-
pering can show you clipping. If the eyedropper numbers don't vary by
much in a given area, that means there is probably clipping.
Histograms have some fans. I'm not one of them. The best thing
a histogram can show you is whether there is clipping at either end
in one of the color channels. If you have histogram analysis tools in
your preferred color grading application, keep an eye on the histo-
grams while you're doing a correction using one of the other methods,
like with an RGB Parade. You'll start to see how you can balance the
colors and to dial in a nice spread on your tonal range using the his-
tograms. Histograms are actually quite good at setting the limits on
your tonal ranges, but for balancing, I've found them to sometimes be
quite deceptive. The basic concept for balancing with histograms is the
same as with an RGB Parade. You are looking to match the starting
and ending positions of the limits of each color channel. To compare
fixed vector (position)
around the vectorscope
(
Figure 1.14
). Apple Color
includes a cool 3D vector-
scope that allows you to
rotate the vectorscope in
3D space to see luminance
displayed as well; 2D vec-
torscopes cannot display
luminance information.
graticule:
The overlay on
the scope that indicates
levels and positioning
information. The graticule
does not change unless the
user changes it. It is usually
customizable to display
various scales and to pro-
vide information on how
the trace signal is being
displayed. It is analogous
to the legends and lines
on a chart or graph. The
latitude and longitude lines
on a map are the map's
graticule.
trace:
Part of the wave-
form or vectorscope display
that reacts to the incoming
video information. The
trace is a representation of
your video image on the
waveform or vectorscope.
Nontechnically, it's the
squiggly stuff.
cell:
This term is used
to describe one of the
three (or four) separate
images on the RGB Parade
waveform corresponding to
the individual red, green,
blue and—in the case of a
YRGB display—luminance
signals.
Fig. 1.15
The image represented in the RGB Parade and histogram.
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