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— Luma Chroma Same Threshold: Ordinarily, the Luma and Chroma Threshold parameters are ganged together so that adjusting one adjusts both. However, you can ungang these parameters to adjust different amounts of noise reduction to each component of the image. For example, if an image softens too much at a certain level of noise reduction, but you find more color speckling than luma noise, you can lower the Luma Threshold to preserve detail while raising the Chroma Threshold to eliminate color noise.
— Blend: Lets you dissolve between the image as it’s being affected by the Spatial NR parameters (at 0.0) and the image with no noise reduction (100.0). This parameter lets you easily split the difference when using aggressive spatial noise reduction.
Global Blend
— Blend: Lets you dissolve between the image with no noise reduction (1.0) and the image with both Spatial NR and Temporal NR at their current settings (0.0).
Using Noise Reduction
The following procedure suggests a method of using the Noise Reduction (NR) parameters to achieve a controlled result.
1 Enable Temporal NR by choosing 1 to 5 frames from the Number of Frames pop-up menu. Keep in mind that more frames dramatically increase the render time of this effect, while it may or may not significantly improve the result, depending on your material.
2 Choose options from the Motion Est. Type and Motion Range drop-down menus corresponding to how much motion is in the image. If there’s a lot of motion, you may need to choose Better and Large. If there’s not very much motion, lesser settings may suffice.
3 With Luma and Chroma Threshold linked, slowly raise either parameter until you just start to see a reduction in noise within nonmoving areas. Then make smaller adjustments to determine the maximum amount you can add without creating artifacts or overly softening detail.
4 If there’s obviously more chroma than luma noise in the image, you can disable Luma/Chroma linking at a satisfactory level of luma noise reduction, and then raise the Chroma Threshold to address color speckling in the picture.
5 Suppose you’re not satisfied with the tradeoff between the maximum possible threshold of noise reduction and the prevention of motion artifacts. In that case, you may want to adjust the Motion Threshold setting, lowering it to omit more of the motion from the noise reduction operation, or raising it to include more motion. If you’re still not satisfied, you can also try better Motion Est. Type and Motion Range settings.
Keep in mind that the strength of Temporal NR is to reduce noise in unmoving parts of the image. When you’ve achieved the best tradeoff between noise reduction in the still areas and avoidance of motion artifacts in the moving areas of the image, it’s time to turn to Spatial NR to further eliminate noise throughout the rest of the picture.
6 Enable Spatial NR by raising either the Luma or Chroma Threshold parameters, which are linked by default, until you strike a suitable balance between the reduction of noise and an unwanted increase in image softness.
7 It’s recommended to choose the Enhanced option from the Spatial NR mode pop-up, as it will yield the best possible results. However, this can be processor-intensive, so if you need better real-time performance, you can switch the mode to Faster and compare results.
8 If there’s obviously more chroma than luma noise in the image, you can disable Luma/Chroma linking at a satisfactory level of luma noise reduction, and then raise the Chroma Threshold to apply more aggressive Spatial NR to address color speckling in the picture.
9 If you’ve had to use a high Spatial NR Luma or Chroma Threshold setting to reduce noise visibly, and areas of detail look a bit chunky or aliased, you can choose a larger setting from the Radius pop-up menu to enable a more detailed analysis of the scene.
This will result in higher visual quality, but larger NR Radius settings are more processor-intensive and may reduce real-time performance if you don’t have adequate GPU resources available to your system.
10 If you’ve found suitable noise reduction settings, but the result is too aggressive and makes the image appear too processed, you can try raising the Spatial NR and/or Temporal NR Blend
parameters to fade between the noise reduction added by each set of controls, and the image as it was before you added noise reduction.
Try Applying Temporal NR First, then Applying Spatial NR
Because Temporal NR analyzes multiple frames for its noise isolation, it tends to be better at preserving detail accurately in regions of the image where there’s little motion. If you try applying Temporal NR first and get a successful result, even if only in part of the image, you may reduce how much Spatial NR you have to apply, thus improving the overall quality of your final result.
Keep in mind that while Temporal NR does a great job in unmoving parts of an image but is less effective when dealing with subjects in motion, Spatial NR can reduce noise everywhere in the frame falling below its threshold, even when there’s motion. Ultimately, a combination of the two is almost always going to be a winning combination.
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 be able to perceive the additional quality. You’ll waste processing time on an unnecessary level of correction.
It’s a good idea to evaluate 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.