User Manual

Spatial NR Radius, How Large Should You Go?
Larger NR Radius settings can dramatically improve the quality of high-detail regions in shots
where you’re using aggressive Spatial noise reduction, but it’s not necessary to always jump to
the large Radius setting, which provides the highest precision. In many cases, when evaluating
an image that you’re applying noise reduction to, you may not actually be able to perceive the
additional quality, and you’ll waste processing time on an unnecessary level of correction.
It’s a good idea to make sure that you’re evaluating the full-frame image on a large enough
display to see the noise you’re working on within the viewing context of the intended audience.
Zooming really far into a clip while applying noise reduction may encourage you to use higher
quality settings than are necessary, because an excessively enlarged detail of an image lets
you see subtle changes that you wouldn’t notice at actual size.
Limiting Noise Reduction in Useful Ways
As with any other correction in the Color page, noise reduction can be limited using HSL
Qualification or Power Windows. This means you can focus your efforts on reducing noise in
the most problematic areas of an image (for example, in shadows and background regions),
while sparing elements that you don’t want to affect (such as faces or better-lit areas of
the image).
Furthermore, you can use Spatial NR in lieu of Blur operations to perform a subtler form of
complexion smoothing, using the HSL qualifier or a window to isolate an actor’s skin tone for
targeted noise reduction.
Controlling the Order of Operations for Noise Reduction
You can apply noise reduction at any point in your image processing tree using a dedicated
node. If you have an image with noise that you think might be enhanced by whatever
corrections you need to make (increasing the contrast of underexposed clips often increases
whatever noise is within an image), there are two approaches to noise reduction:
 Apply noise reduction at the beginning of a node tree: This lets you pre-emptively
eliminate any noise before it becomes a problem as a result of whatever adjustments
you’re planning to make. The result can be smoother, but you may also notice that the
edge detail within the image is a bit softer.
 Apply noise reduction at the end of a node tree: The alternative is to make your
adjustments first, and then apply noise reduction in a separate node afterwards. In this
case, you may find that the noise reduced regions of the image aren’t quite as smooth,
however the edge detail within the image may be visibly sharper as a result.
 Apply noise reduction to only one color channel of an image: Using the Splitter/
Combiner nodes, you can also apply noise reduction to only one color component
of an image. If you’re grading a video clip with a noisy Blue channel, this can be a
way to focus noise reduction where it’s needed. Isolating a single color channel for
noise reduction is also possible using the Channels selection when right-clicking a
node. By selecting the specific channel numbers in this node corresponding to your
color space (RGB, YUV, LAB, etc.), you can limit the noise reduction operation to the
appropriate channels only.
Neither result is universally better or worse than the other. Which is preferable depends on the
image you’re working on, and the type of result you’re looking for (you might prefer some shots
to be a bit softer, while you’d like other shots to be a bit sharper). The real point is that the node-
based image processing of DaVinci Resolve lets you choose which technique works
best for you.
Chapter – 134 The Motion Effects and Blur Palettes 2997