The Fundamental Technique

The Fundamental Technique

Integration of a foreground element into a background
scene often follows the same basic steps:
1. First match overall contrast without regard to color,
using Levels (and in most cases, working only on the
Green channel). When matching the black and white
points, pay attention to atmospheric conditions.
2. Next, study individual color channels and use Levels to
match the contrast of each channel (as needed—not all
images contain so fundamental a color imbalance).
3. Match the color of the midtones (gamma), channel
by channel, using Levels or Curves. This is sometimes
known as gray matching and is easiest when an object in
the background scene is known to be colorless gray (or
something close).
4. Evaluate the overall result for other factors infl uencing
the integration of image elements—lighting direction,
atmospheric conditions, perspective, grain or other
ambient movement, and so on (all of which and more
are covered in this book).
The overall approach, although not complicated or even
particularly sexy, can take you to places your naked eye
doesn’t readily understand when it is looking at color. Yet,
when you see the results, you realize that nature beats logic
every time.
The sad truth is that even an experienced artist can be
completely fooled by the apparent subjectivity of color.
Figure 5.24 shows an example in which seeing is most defi -
nitely not believing. Far from some sort of crutch or nerdy
detail, channel-by-channel analysis of an image provides
fundamental information as to whether a color match is
within objective range of what the eye can accept.

Ordinary Lighting

We begin with a simple example: inserting a 3D element
lit with ordinary white lights into a daylight scene. As you
can see in Figure 5.25, the two elements are close enough
in color range that a lazy or hurried compositor might be
tempted to leave it as is.

With only a few minutes of effort, you can make the plane
look as though it truly belongs there. Make sure the Info
palette is somewhere that you can see it, and for now,
choose Percent (0–100) in that palette’s wing menu to
have your values line up with the ones discussed here (you
can, of course, use whatever you want, but this is what I’ll
use for discussion in this section).
This particular scene is a good beginner-level example
of the technique because it is full of elements that would
appear monochromatic under white light; next we’ll move
on to scenes that aren’t so straightforward. The background
is dominated by colorless gray concrete, and the
foreground element is a silver aircraft.
Begin by looking for suitable black and white points to use
as references in the background and foreground. In this
case, the shadow areas under the archways in the background
and underneath the wing of the foreground plane
are just what’s needed for black points—they are not the
very darkest elements in the scene, but they contain a similar
mixture of refl ected light and shadow cast onto similar
surfaces, and you can expect them to fairly nearly match.
For highlights, you happily have the top of the bus shelter
to use for a background white point, and the top silver
areas of the plane’s tail in the foreground are lit brightly
enough to contain pure white pixels at this point.

To correct for these mismatches, apply Levels to the
foreground and move the Output Black slider up to about
7.5%. This raises the level of the blackest black in the
image, lowering the contrast.


Black levels in the red channel are clearly still too low in
the foreground, so raise them to match. Switch the Channel
pop-up in Levels to Red, and raise Red Output Black
slightly to about 3.5%. You can move your cursor from foreground
to background and look at the Info palette to check
whether you have it right, but the great thing about this
method is that your naked eye usually evaluates variations
in luminance correctly without the numerical reference.
Now for the whites. Because the background highlights
have slightly less blue in them, switch to the blue channel
(clicking the blue marker at the bottom of the Composition
panel or using Alt+3/Option+3). Pull back slightly to

where you can see the top of the bus shelter and the back
of the plane. Switching Levels to the blue channel, lower
the Blue Output White setting a few percentage points to
match the lower blue reading in the background. Back in
RGB mode (Alt+3/Option+3 toggles back from blue to
RGB), the highlights on the plane take on a more sunlit,
yellow quality. It’s subtle, but it seems right.
What about the midtones? In this case, they’re taking care
of themselves because both the foreground and background
are reasonably well balanced and these corrections
are mild.
 Displays the result, with the same regions targeted
previously, but with the levels corrected. To add an
extra bit of realism, I also turned on motion blur, without
yet bothering to precisely match it (something you will
learn more about in Chapter 8). You see that the plane is
now more acceptably integrated into the scene.
Work on this composite isn’t done either; besides matching
the blur, you can add some sun glints on the plane as
it passes, similar to those on the taxi. On the other hand,
you can tell that the blur on the plane is too heavy for the
pilot’s absence from the cockpit to be noticeable, a good
example of how an initial pass at a composite can save a lot
of extra work.