[This article was first published in the June,
2004, edition of "Larry's FCP Newsletter".]
Knowing how to read video scopes is critical to a variety of tasks
with Final Cut Pro. This technique is designed to give you a basic
understanding of how to read them, because in a future technique, I'll
show you how to use scopes for color correction.
Why use scopes? Because, it's the only way you can be sure of your
video and color levels.
Waveform Monitor
The Waveform Monitor displays the black, gray, and white levels in
your picture. Think of it as a measure of your exposure. Each white
dot in the scope represents the luminance, or gray-value, of a pixel
in your video image.
A well-exposed picture will have lots of white dots at all different
levels. A poorly-exposed picture will tend to have all the dots clumped
in just a part of the scope.
Further, the waveform monitor directly corresponds to the image it
measures from left to right. That is, looking left to right on the
scope corresponds to looking left to right in the image. This means
you can look at a scope and tell immediately where the dark and bright
images are and roughly where they are located in the image itself.
Here's an example. This close-up of a stage actor clearly shows the
black background, and the close-up of his face in the center. (Images
courtesy of Paul Jordan.) The heavy line slanting upward at the bottom
of the scope is the dark gray of the background, with the fountain
of pixels in the middle representing all the shades of gray in his
body.
Notice that it is easy to see where his body is on the scope, but
you can't use the scope to identify specific features. The waveform
monitor only shows the specific gray-scale value of each pixel in the
image, and provides its position only in terms of left-to-right. The
waveform has no concept of a pixel being in the upper half, or lower
half, of the frame.
Here's another example. This 3-shot shows three colorful actors.
Notice how evenly the exposure covers the scope. There are whites,
blacks and lots of different shades of gray. Remember, the height of
the pixels on the scope represents their gray-level, with white near
the top, and black near the bottom.
In general, images look better when they have lots of different gray
levels, than when they all clump together.
If you are shooting DV, your levels will vary from digital black
(measured as 0%) through to digital white (measured as 109%). If you
are shooting Beta, your levels will vary from black at 0% to white
at 100%. The area above 100% is called "super-white." If
you are outputting to DV, this isn't a problem. If you are outputting
for broadcast, you'll need to use the scope to measure your levels
as you adjust them, because they can't exceed 100%.
(For more information on working with white vs. super-white, read
this article.)
Vectorscope
However, the waveform monitor does not tell us anything about the
color in a picture. For that, we need to use the Vectorscope.
The Vectorscope shows colors in two dimensions: the shade of the
color, represented by where the color falls around the circle and the
amount of color, represented by how far the color is out from the center.
On the vectorscope, black, white, and all shades of gray are represented
by a single dot in the center of the circle. A fully-saturated color
would be out near the edge of the circle.
One of the real values in using the vectorscope is that it helps us
keep our colors, "legal." Just as there are whites that are
too white to be "broadcast-legal," so, also, there are colors
which are too intense to be safe.
There are six boxes in the vectorscope, representing red (upper left),
yellow, green, cyan (lower right), blue and magenta. A color can be
considered "broadcast-safe" if it falls within a loosely-defined
rectangle drawn by connecting the tops of each of the six color boxes
in the vectorscope.
Here is our first example, again. Notice that the colors are saturated
(radiating far out from the center of the circle) and skewed toward
yellow-red.
Here's our second example, Notice the colors are much less saturated,
though still pointing toward yellow-red, because the principal color
in the shot is skin-tone.
One other things. See the purple line, at about a 45 degree angle
from the top? This represents flesh tone. The magical thing about this
line is that, in general, regardless of whether the skin of your talent
is black, white, red, yellow or brown, their skin tone will fall on
or near this line. This is because everyone has the same red blood
under their skin, which provides the dominant color to skin. Knowing
this makes color-balancing a whole lot easier.
Now that you know the basics of reading the two most important video
scopes, you can use this knowledge to take your projects to the next
level in quality.
This article is from the June, 2004, issue of "Larry's
FCP Newsletter," a very cool FREE monthly Final Cut Pro
newsletter -- subscribe at Larry's web site: www.larryjordan.biz.
Larry Jordan is a post-production consultant and an Apple-Certified
Trainer in Digital Media with over 25 years experience as producer,
director and editor with network, local and corporate credits. Based
in Los Angeles, he's a member of both the Directors Guild and Producers
Guild.
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Text copyright 2004 by Larry Jordan. All rights reserved.
