Smooth strength control
For many shots, overall Strength is the main control you need.
Resolve FX · Blur · 04
Gaussian Blur DaVinci Resolve
Gaussian Blur is the straightforward smooth blur in the Resolve FX Blur family. It is useful when the goal is clean softening without a directional vector, depth map or iteration-driven box character.
The page follows the real DaVinci Resolve 21 panel: Strength, Split Horizontal and Vertical, Horizontal / Vertical Channel Adjustment, Border Type, Blur Alpha and Global Blend.
StrengthSplit H/VChannelsBorder TypeGlobal Blend
Independent axes when needed
Split H/V only when the shot benefits from different horizontal and vertical blur amounts.
Per-channel control
RGB and Alpha controls make the effect flexible without changing the whole grade.
Blend at the end
Build the blur first, then decide how much should remain with Global Blend.
Controls
Simple at first glance, flexible when the axes are split
For a normal soft blur, Strength may be all you need. The deeper controls matter when the shot requires separate H/V shaping, channel-specific behaviour, alpha processing or deliberate edge handling.
Strength and Horizontal Channel Adjustment
Strength sets the overall Gaussian Blur amount. By default the blur behaves uniformly, but Split Horizontal and Vertical lets you separate the axes. Horizontal Channel Adjustment then gives independent Red, Green, Blue and Alpha control along the horizontal axis.
Strength — overall Gaussian Blur amount
Split H/V — independent axis control
RGB + Alpha — per-channel control
Vertical Channel Adjustment
The vertical block applies the same per-channel logic from top to bottom. With Split Horizontal and Vertical enabled, Gaussian Blur can be stretched along one axis or deliberately given different channel behaviour horizontally and vertically.
Independent vertical strength per channel
Useful for non-symmetrical blur
Equal RGB values keep the blur neutral
Border Type and Blur Alpha
Border Type defines where Gaussian Blur gets missing information beyond the frame edges. This becomes most visible when a strong blur reaches the border. Blur Alpha includes the alpha channel and matters for transparent or keyed elements.
Black / Replicate / Reflect / Wrap-Around
Blur Alpha — blur transparency too
Check Border Type on strong edge blur
Global Blend
Global Blend reduces the entire configured Gaussian Blur with one control. A practical workflow is to shape the blur first, then bring some of the original image back through Blend without rebuilding the rest of the settings.
1.000 — full effect
Lower values restore more of the original
Useful for a more natural final result
Border Type
Frame-edge behaviour matters more as blur gets stronger
Gaussian Blur needs pixels beyond the visible image boundary. Border Type defines how Resolve invents that missing information, so the choice can affect dark edges, mirrored structures or cross-frame wrapping.
Black
Pixels outside the frame are treated as black, so a strong blur at the edge can pull dark values inward.
Replicate
The edge pixels are extended outward. This is often useful when you want the border to stay visually stable.
Reflect
The image is mirrored beyond the edge, creating a smoother continuation for many blurred shots.
Wrap-Around
Pixels wrap from the opposite side of the frame. It is specialised and can create obvious interaction between opposite edges.
Practical use
Where Gaussian Blur is the sensible choice
Privacy and local censor blur
Put Gaussian Blur on a dedicated node, isolate the region with a Window or matte and track it if necessary.
Soft background reduction
A restrained local Gaussian Blur can reduce distracting background detail without introducing an obvious directional smear.
Elliptical H/V blur
Split Horizontal and Vertical when the shot needs a blur that is wider in one axis than the other.
Controlled channel softness
Different channel multipliers can create deliberate colour softness, but equal RGB values are the safer default for normal grading.
Node workflow
Keep the blur local, readable and easy to dial back
01
Create a separate FX node
Keep Gaussian Blur away from unrelated primary grading so it can be bypassed and compared instantly.
02
Set Strength before splitting axes
Start with the simplest possible blur. Split the axes only when the shot genuinely needs an anisotropic result.
03
Check borders and alpha
Strong blur near the frame edge or on transparent elements can expose Border Type and Blur Alpha choices.
04
Finish with Global Blend
Pull back the final mix until the blur supports the shot rather than looking pasted on top of it.
Typical mistakes
A smooth blur still looks artificial when it is overused
Using too much Strength
Gaussian Blur is smooth, but excessive values quickly erase texture and make local corrections look artificial.
Splitting H/V without a reason
Independent axes are useful, but unnecessary H/V differences can make a natural blur look stretched.
Changing RGB channels accidentally
Different channel values can create colour fringing. Keep them matched unless the colour separation is intentional.
Ignoring Border Type
Edge artefacts often become visible only after Strength increases, so check borders before finishing the shot.
Gaussian Blur vs Box Blur
Use Gaussian for smoothness, Box when iterations are part of the behaviour
Gaussian Blur
When smoothness is the main goal
Gaussian Blur is the direct choice for neutral smooth softening with optional H/V and channel refinement.
Box Blur
When iterations are part of the blur behaviour
Box Blur exposes Number of Iterations and is useful when its more structural box character is part of the task.
Box Blur
Technical model
Gaussian Blur: how the effect behaves in a real node tree
Gaussian Blur is the baseline choice when you need a visually smooth blur without a direction vector, aperture shape or scene-depth model.
A Gaussian profile weights nearby pixels more strongly and reduces their contribution smoothly with distance, which explains its softer character versus a coarse box profile. Blackmagic does not document the exact kernel or map Strength to a literal sigma/radius, so UI values should not be treated as physical units.
Gaussian Blur does not know about subjects, background or depth: it filters the image rather than reconstructing a lens.
Use it when
- soft beds, glow preparation and local softening
- fast blur without a geometric direction
- neutral RGB blur with matched channels
Choose another tool when
- you need shape-driven bokeh — use Lens Blur
- you need motion streaks — use Directional/Zoom/Radial
What each control changes — and what to inspect
| Control / layer | Meaning | Inspection point |
|---|---|---|
| Strength | Primary blur amount. | Watch skin texture, hair and other high-frequency detail. |
| Split H/V | Makes the smooth blur anisotropic. | Check circular or square objects — they reveal axis imbalance quickly. |
| Channel adjustment | Different RGB values turn neutral blur into chromatic smear. | Keep RGB equal for clean-up work. |
| Border / Alpha | Controls out-of-frame sampling and transparency. | Test the frame boundary and matte edge directly. |
Production workflow
- 01Start on a dedicated node with no localisation.
- 02Choose the minimum Strength that solves the task.
- 03Split H/V only if needed; add channel differences deliberately.
- 04Check Border Type at frame edges and through motion.
- 05Add and track a Window/Qualifier when the blur is local.
Diagnostics: symptom → cause → fix
Skin looks plastic
Likely cause: Blur is replacing texture instead of solving a local issue.
Fix: Reduce Strength, localise the node and restore texture after the blur.
Bright/dark frame contamination
Likely cause: Unsuitable Border Type.
Fix: Compare Replicate and Reflect on the same frame.
Blur does not feel like a lens
Likely cause: Gaussian does not model aperture/bokeh.
Fix: Switch to Lens Blur or CineFocus.
Performance
Gaussian Blur is conceptually lighter than depth-aware effects, but large strong blurs are still expensive. At 4K/8K, watch playback FPS and cache heavy nodes when needed.
Animation & keyframes
Animating Strength works for reveals/transitions, but the change should have a clear motivation. For motion along a vector, Directional Blur is usually a better model than forcing H/V Gaussian into a motion effect.
Node placement
Most often, use a dedicated node after the base grade and before final grain/sharpening. In glow-like constructions, placement depends on what is later mixed back with the original signal.
Choose by geometry
When Gaussian Blur is not the right FX
Box Blur
rectangular local averaging shaped by Iterations
simple controllable blur with H/V and channel shaping
Open guide
Directional Blur
linear vector driven by Angle
motion smears and horizontal/diagonal streaks
Open guide
Lens Blur
aperture and bokeh profile
optical defocus character without depth analysis
Open guide
Mosaic Blur
discrete cells and pixelation
detail concealment and graphic stylisation
Open guide
Radial Blur
rotation around a centre
spin, vortex and rotational motion
Open guide
Zoom Blur
rays toward or away from a centre
rush, punch-in/out and depth-like transitions
Open guide
AI CineFocus
depth-aware virtual lens
different defocus across foreground, subject and background
Open guide
Nodes and pipeline
Where to place FX and preserve operation order.
Related chapter
Qualifier · Windows · Tracker
How to localise blur and keep the matte tracked over time.
Related chapter
Sizing
Coordinates, crop/zoom and FX-centre behaviour after transforms.
Related chapter
Scopes
Check RGB contamination, clipping and technical side effects.
Related chapter
Primary references used for this technical layer
DaVinci Resolve 21 · New Features Guide
AI CineFocus and current Resolve 21 behaviour.DaVinci Resolve 20 · New Features Guide
Keyframable Open FX / Resolve FX in the Keyframe and Curve Editor.Blackmagic Design · Color
Official Color page and Resolve FX workflow context.
AI CineFocus and current Resolve 21 behaviour.DaVinci Resolve 20 · New Features Guide
Keyframable Open FX / Resolve FX in the Keyframe and Curve Editor.Blackmagic Design · Color
Official Color page and Resolve FX workflow context.
Control names and panel layout are also cross-checked against the real DaVinci Resolve 21 screenshots shown earlier on this page. Where Blackmagic does not publish implementation math, this guide describes observable behaviour and does not invent a proprietary kernel.
FAQ
Gaussian Blur in DaVinci Resolve: common questions
What does Gaussian Blur do in DaVinci Resolve?
It applies a smooth blur profile to the image. Strength controls the overall amount, while optional H/V splitting and channel controls let you shape the blur more precisely.
What is Split Horizontal and Vertical for?
It lets horizontal and vertical blur be controlled independently, which is useful when the blur needs to be wider along one axis.
Why are Red, Green, Blue and Alpha separate?
They control how strongly each channel participates in the blur. Equal RGB values keep the result neutral; different values can intentionally create colour separation.
What does Blur Alpha do?
It includes the alpha channel in the blur and matters when the effect is applied to transparent or keyed elements.
Gaussian Blur or Box Blur — which is better?
Neither is universally better. Gaussian Blur is the direct choice for a naturally smooth blur profile, while Box Blur is useful when iterations and its more structural box behaviour are part of the task.
Continue the catalog
Four Blur FX are now documented in order
01 · Box Blur
H/V controls, iterations, borders and alpha.
02 · AI CineFocus
Depth-aware focus, bokeh, lens properties and grain.
03 · Directional Blur
Angle-driven blur, Realistic / Stylized and channel control.
Next in Blur
Lens Blur
Aperture-shaped bokeh, Quality, Blur Size, Anamorphism and optical controls are now documented on the next page.