Graphics Reference
In-Depth Information
Render Layers, but from entirely different scenes, which may have entirely different render settings (OSA, Ambient
Occlusion, SSS, Ray Tracing, etc.). When working with Render Layers and only one Scene, Blender does a single
render, piping the results around as required. But when a second (or third, etc.) Scene is involved, it actually per-
forms entirely separate renders. While this will take longer, it can also allow you to render things that you would
not ordinarily be able to render at once due to RAM constraints.
Better Renders
We have already shown how RGB Curves nodes are placed after each input node. Let's examine a couple of
common uses for an RGB Curves node.
Contrast Boost
Figures. 15.41 and 15.42 show a frame from shot 6, both before and after contrast enhancement. In nontechnical
terms, a contrast boost involves making the darks a bit darker, the lights a bit lighter, and leaving the middle alone.
To translate this into RGB Curves, the top end of the curve, which represents the highlight area, needs to go
up (lighter), and the low end of the curve, which represents the shadows, needs to go down (darker). The curve
that made the adjustment between the two previous
illustrations is shown in Figure 15.43. This is commonly
referred to as an ā€œSā€ curve, or a standard contrast curve.
More contrast will usually make an image more inter-
esting. However, you must be sure not to overdo it.
How much is too much? First, you do not want to lose
visible detail in either the highlight or shadow range. If
you examine the output of the RGB Curves node and
the details have disappeared, like Figure 15.44, push the
curve back toward a straight line a bit.
Figure 15.41
A shot with unaltered contrast
Figure 15.42
The contrast-enhanced shot
Figure 15.43
The contrast ā€œSā€ curve
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