Resolve FX · Blur · 06
Mosaic Blur turns the image into a controlled grid of cells. Unlike a soft blur, it deliberately removes detail and replaces it with a graphic pixelated structure, making it useful for privacy masking, stylised transitions and deliberate digital looks.
This guide follows the real Resolve 21 panel: Pixel Frequency, Cell Shape, Aliasing, X/Y Offset, Aspect, Antialias Result, Blur Alpha, Whole Cells Only and Global Blend.
Controls
The effect is simple, but small changes in Pixel Frequency, Cell Shape and Aliasing completely change the visual character. Advanced Controls then let you align the grid more precisely with the shot.
Pixel Frequency controls cell density and therefore the apparent pixel size. Cell Shape changes the grid geometry between Square, Hexagon and Triangle, while Aliasing controls how hard or smooth the cell boundaries appear.
X Offset and Y Offset shift the mosaic grid relative to the image, while Aspect changes cell proportions. Antialias Result controls final smoothing, Blur Alpha includes transparency in the effect, and Whole Cells Only helps keep complete cells at the edges.
Global Blend mixes the configured Mosaic Blur back with the original image. It is useful when you want to keep the graphic cell structure but reduce the effect without rebuilding Pixel Frequency or Aliasing.
Cell Shape
Square creates the familiar pixel-block look, Hexagon feels more graphic and patterned, while Triangle creates a sharper geometric texture. The best choice depends on whether the job is privacy, UI styling or a deliberate transition.
Classic block pixelation. The most familiar option for privacy and censorship.
A more decorative cellular pattern with a digital or technical feel.
A sharper geometric texture that works well for stylised graphics and transitions.
Practical use
Place Mosaic Blur on a dedicated node and limit it with a Power Window or key to hide faces, number plates, screens or sensitive details.
Hexagon or Triangle cells can create a deliberately graphic digital texture that feels very different from ordinary square pixelation.
Animate Pixel Frequency, Blend or the node key to move between a readable image and a coarse mosaic for transitions or reveals.
A local Mosaic Blur can simplify a busy background while preserving a sharp foreground subject through masking.
Typical mistakes
Very large cells destroy context quickly. For privacy that may be fine, but for styling it often feels clumsy unless the composition is designed for it.
A small X/Y Offset can make the pattern sit much better on a face, logo or interface element. Default alignment is not always the best alignment.
If the effect is used on keyed or transparent elements, check Blur Alpha and the node alpha path so the mosaic does not create unexpected edges.
Mosaic Blur is a graphic abstraction, not a soft blur. If the goal is natural defocus, Gaussian Blur or Lens Blur is usually a better choice.
Mosaic Blur vs Box Blur
Choose it when visible cells and deliberate pixelation are part of the result.
Choose it when the task is actual softening rather than visible pixel cells.
Mosaic Blur is less about softening and more about deliberately destroying spatial detail by grouping the image into large cells. That is a fundamentally different visual language from Gaussian/Box blur.
| Control / layer | Meaning | Inspection point |
|---|---|---|
| Pixel Frequency | Determines how much spatial information remains in the cells. | Scale the image down and check whether the concealed detail is still recognisable. |
| Cell Shape | Changes the graphic structure of the grid. | For concealment shape is secondary; for stylisation it is part of the design. |
| Offsets | Shift the grid relative to the subject. | Check whether a cell boundary accidentally preserves a critical detail. |
| Aliasing / Alpha | Changes cell edges and transparency handling. | Inspect matte edges and fine diagonals. |
Likely cause: Cells are too fine or the matte lags behind.
Fix: Use larger cells and fix tracking/window size.
Likely cause: Grid/offset or matte motion does not follow the subject.
Fix: Stabilise tracking and avoid unnecessary offset animation.
Likely cause: Internal detail is hidden but the exact silhouette remains.
Fix: Increase matte coverage/softness or conceal a larger region.
Mosaic is generally lighter than complex bokeh/depth processing, so tracking/masks and the overall node tree often dominate cost. Still verify the final result at delivery resolution.
Offsets and Pixel Frequency can be animated for digital transitions. For concealment, avoid decorative animation: stable complete coverage is more important than grid motion.
For concealment, use a dedicated late node after the base grade so later sharpening/detail operations cannot restore readability. Global grain can remain after it if needed.
rectangular local averaging shaped by Iterations
simple controllable blur with H/V and channel shaping
smoothly weighted blur without a directional vector
natural softness, defocus beds and clean-up
linear vector driven by Angle
motion smears and horizontal/diagonal streaks
aperture and bokeh profile
optical defocus character without depth analysis
rotation around a centre
spin, vortex and rotational motion
rays toward or away from a centre
rush, punch-in/out and depth-like transitions
depth-aware virtual lens
different defocus across foreground, subject and background
Where to place FX and preserve operation order.
How to localise blur and keep the matte tracked over time.
Coordinates, crop/zoom and FX-centre behaviour after transforms.
Check RGB contamination, clipping and technical side effects.
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
Mosaic Blur replaces image detail with a grid of cells. You can control cell density, shape, aliasing, grid position, aspect and final blend.
Pixel Frequency controls how dense the mosaic is. Higher density creates smaller cells; lower density creates larger, more obvious blocks.
Square gives classic pixelation, Hexagon creates a more patterned look and Triangle produces a sharper geometric texture. Choose by visual purpose rather than by a fixed rule.
Put Mosaic Blur on its own node, isolate the face with a Power Window or key, track the mask, then set Pixel Frequency and Blend to the required privacy level.
Mosaic Blur creates visible cells and deliberately removes detail. Box Blur actually softens neighbouring pixels and is used when you want blur rather than pixelation.
Blur catalog
Motion geometry
Radial Blur is the better choice when the image should smear around a rotation centre instead of breaking into cells.
