RESOLVE FX · GEOMETRIC PIXELATION
Mosaic Blur.
A grid can hide detail.
Only coverage makes it reliable.
Mosaic Blur replaces fine image structure with geometric cells. Pixel Frequency decides how much spatial information survives, Cell Shape decides the visual language, and Advanced Controls decide where the grid sits and how it behaves at a Power Window boundary. For privacy, tracking and final-export inspection matter as much as the effect itself.
Pixel Frequency
Shape + Offset + Aspect
Window + Alpha + Blend
In the lab, switch to Privacy Window, enable Whole Cells Only, then change X/Y Offset. The edge behavior makes the purpose of that checkbox much easier to understand than a one-line definition.
INPUTMOSAICWindow and alpha controls
Whole Cells Only is demonstrated only at the ellipse Window boundary. Cells that cross the Window are clipped when off and omitted when on.
Independent teaching visualization, not a Resolve renderer. Frequency, Aliasing, Shape geometry, Aspect, offsets, antialiasing, alpha, and Whole Cells Only are illustrative mappings; they do not reproduce Resolve’s internal OFX implementation or numeric scale. Use the actual screenshots below for the real panel.
Actual Resolve captures + an explicitly independent mosaic teaching renderer.
10 controls · 5 captures · 4 exercises01THE CELL MODEL
Mosaic Blur removes spatial detail by changing the image into a grid, not by making it optically soft.
That distinction explains almost every control. Frequency governs retained information, topology governs the visible pattern, and Window coverage decides whether the treatment actually reaches the subject you meant to conceal.
A cell replaces detail with one sampled color
Mosaic Blur does not soften neighboring pixels like an ordinary soft blur. It divides the affected region into geometric cells and replaces local detail with a coarser representation. The key practical question is therefore not “blur strength” but how much spatial information remains inside the grid. Larger cells preserve fewer small identifying features.
Frequency, Shape, and Aliasing answer different questions
Pixel Frequency sets grid density, Cell Shape switches topology between Square, Hexagon, and Triangle, and Aliasing changes how tightly each cell samples the area underneath it. That is not the same job as Antialias Result, which separately enables extra processing for cleaner boundaries between cells.
Privacy depends on complete coverage, not on the effect alone
For concealing a face, plate, or document, Mosaic Blur usually belongs on a dedicated node with a correct Power Window or matte and reliable tracking. Whole Cells Only specifically concerns the Window boundary: it limits displayed cells to those completely inside the window. Even a very coarse mosaic fails if the mask slips for a few frames or Blend restores source detail.
Control semantics and version anchor: Blackmagic Design · Resolve 21.1 Reference Manual ↗ · Blackmagic Design Support ↗
02THE ACTUAL INSPECTOR
Ten controls, separated into density, placement, Window behavior, alpha, and final mix.
The screenshots are actual Mosaic Blur captures from the project archive. Captured values are one panel state, not declared defaults or recommended settings.
Grid and sampling
Decide how much information the mosaic may retain, then choose its geometry.
- Pixel Frequency
Controls cell size and therefore the density/resolution of the mosaic grid. For privacy work this is the primary control over retained spatial information: a denser grid preserves more structure, while larger cells remove more of it. The 100.0 value in the screenshot is one captured state, not a recommended preset.
CheckInspect the subject at 100% viewer scale and again at the actual delivery/display size. Detail that seems lost when enlarged can sometimes become readable again after scaling or from adjacent frames.
- Cell Shape
Selects the base geometry: Square, Hexagon, or Triangle. Shape changes the visual language and boundary layout, but it does not by itself guarantee stronger concealment; adequate cell size and stable localization matter more for privacy.
CheckFor utilitarian censorship, Square is the most immediately recognizable form of deliberate pixelation. Hexagon and Triangle are more useful when geometry is part of the design language.
- Aliasing
Adjusts how tightly each cell samples the image area underneath it. This is a sampling-footprint control, not the switch that smooths the cell boundary itself; extra edge cleanup is handled separately by Antialias Result.
CheckJudge small high-contrast detail inside cells. If Aliasing seems to change only the apparent edge hardness, you are probably evaluating the wrong part of the image.
Advanced Controls · geometry
Offset and Aspect fit the grid to the subject without changing the effect’s basic idea.
- X Offset
Shifts the mosaic grid horizontally relative to the image/window. It is useful when a critical feature happens to fall on a cell boundary and remains more recognizable than expected.
CheckAfter changing Offset, review the whole tracked shot again: a good alignment on one frame does not guarantee equally strong concealment throughout motion.
- Y Offset
Shifts the grid vertically. Together with X Offset it changes grid phase without changing Pixel Frequency or cell shape.
CheckUse Offset for fine alignment, not as a substitute for tracking. If the Window lags behind a face or plate, shifting the grid does not solve the problem.
- Aspect
Changes cell width relative to height. This can create elongated mosaic geometry for a wide UI line or license plate, but it also changes how much information is retained along each axis.
CheckAfter a strong Aspect change, recheck small text and facial features: an elongated cell may conceal detail along one axis while unexpectedly preserving it along the other.
Advanced Controls · edges and alpha
These three controls solve technical questions around cell edges, transparency, and Power Windows.
- Antialias Result
Enables extra processing so lines between cells render more cleanly. This is separate from Aliasing: Aliasing concerns sampling inside the cell, while Antialias Result concerns the rendered geometric boundary.
CheckInspect Triangle/Hexagon diagonals and high-contrast edges at 100%. On fast motion or heavily compressed footage, extra antialiasing may be less obvious than on a static test frame.
- Blur Alpha
Includes the alpha channel in processing along with RGB. Its practical effect appears on transparent or keyed elements when the mosaic must affect not only color but also the transparency edge.
CheckOn ordinary opaque footage the checkbox may appear to do almost nothing. Evaluate it in a real composite with transparency rather than only on flat footage.
- Whole Cells Only
Limits displayed mosaic cells to those that are completely inside a Power Window. It is not a frame-edge mode and does not mean “avoid cropped cells at the image border”; its purpose appears specifically with a local Window/matte.
CheckCompare the edge of a small Window. Enabling the option can produce cleaner complete cells but may narrow coverage near the Window boundary, so privacy masks need adequate margin.
Global Blend
Blend is the final dry/wet, not a way to relax concealment requirements.
- Blend
Mixes the already calculated Mosaic Blur with the source image. In privacy work, lowering Blend restores original detail, so establish sufficient Pixel Frequency and a correct matte first and keep Blend full. Partial mix is more appropriate for graphic transitions or stylized treatments.
CheckIf eyes, text, or digits become visible through the cells again, do not treat that as “softer censorship.” For concealment it is direct evidence that the wet mix is too low or the grid too fine.
03CELL SHAPE IS A DESIGN CHOICE
Square, Hexagon, and Triangle change topology, not the responsibility to conceal.
Resolve 21.1 documents three Cell Shape options. The captured selector on this page shows Square, while the option list below is sourced from the manual rather than reconstructed UI.
Square
▦ ▦ ▦Classic rectangular pixelation. It reads immediately as censorship and works well for faces, plates, and interface data.
Utility baseline
Hexagon
⬢ ⬢ ⬢A hexagonal grid feels less “8-bit” and more decorative. The difference is most visible on static graphics and larger cells.
Cellular pattern
Triangle
△ ▽ △Triangular cells introduce diagonal boundaries and a more active graphic texture. Shape is secondary for privacy but can become part of the composition in motion design.
Angular geometry
Shape can affect how a critical feature falls against cell boundaries, so privacy work still needs a full-clip review. Do not infer that a more complex shape is automatically more secure.
04LOCALIZE BEFORE YOU TRUST IT
For privacy, the Mosaic node and its tracked Window are one responsibility.
Keep the base grade independent, isolate the object with margin, track first, then tune the grid. Whole Cells Only belongs to the Window boundary and should be judged there.
The mosaic and its localization belong together
Apply Mosaic Blur here, constrain it with a tracked Power Window or matte, then tune Pixel Frequency. X/Y Offset and Aspect refine grid placement; Whole Cells Only changes behavior at the Window boundary and can reduce edge coverage if the mask is too tight.
Green lines show image flow. The dashed Window annotation is not a separate serial node. Track the Window before fine-tuning cell geometry; Whole Cells Only acts at that Window boundary. This is a teaching diagram, not a Resolve screenshot.
Related Color workflow: node pipeline ↗ · Power Windows / Tracker ↗
05BUILD IT IN RESOLVE
Four exercises separate privacy, alignment, transition design, and stylization.
The steps are workflows, not magic values. Cell size depends on the actual subject, delivery resolution, motion, and how much disclosure is acceptable.
Conceal a face with tracking margin
Make the face unrecognizable throughout the shot, not just on the setup frame.
PrepareUse a dedicated serial node after the base grade; the Power Window should cover the head with margin for movement and motion blur.
- 01
Add Mosaic Blur to the local node and start with Blend at 1.000.
- 02
Track the Window before fine-tuning cells and repair any frames where tracking loses the subject.
- 03
Set Pixel Frequency until eyes, mouth, and other identifying features stop reading at 100% viewer scale.
- 04
Review the full export at real delivery size and expand the Window if needed; use Whole Cells Only only when you understand its Window-boundary effect.
Across the whole clip the Window never slips, no identifying feature reappears between cells or at the mask edge, and Blend never restores source texture.
License plate or UI line
Conceal a compact rectangular target without affecting unnecessary surrounding image.
PrepareCreate a rectangular Window with margin and use Square as the clearest baseline.
- 01
Choose Pixel Frequency based on character size rather than on how attractive the cells look.
- 02
Use Aspect if the target is strongly elongated horizontally or vertically.
- 03
Use X/Y Offset only to adjust grid phase when a cell boundary accidentally preserves a character feature.
- 04
Check the first, middle, and last frame, then review the full track in motion.
Characters do not become readable on any frame, and the local mosaic does not drift onto adjacent information.
Graphic transition through mosaic density
Use the grid as a deliberate motion element rather than pretending it is optical blur.
PrepareUse a full-frame node with no privacy requirement; choose Cell Shape according to the project design.
- 01
Establish the final Cell Shape and Aspect in a still frame.
- 02
Animate Pixel Frequency from a readable image toward a coarse mosaic or in reverse.
- 03
Add Blend as a separate curve if needed, but do not duplicate the same transition with two controls without a reason.
- 04
Check Antialias Result and the final codec on Hexagon/Triangle diagonals.
The transition has a clear rhythm and retains geometric character without accidental cell-edge flicker.
Stylized background or interface
Simplify a local region while keeping the mosaic pattern as part of the art direction.
PrepareSeparate the foreground/subject with a matte; apply Mosaic Blur only to the background or selected UI zone.
- 01
Choose Shape by design intent: Square for digital/retro language, Hexagon/Triangle for a more graphic pattern.
- 02
Set Pixel Frequency for composition scale, then tune Aspect.
- 03
Evaluate Aliasing and Antialias Result separately: sampling and edge cleanup are different decisions.
- 04
Use Blend only after the geometry itself works.
The mosaic reads as part of the design rather than a random filter and does not fight foreground readability.
06CHOOSE THE RIGHT BLUR MODEL
Pixelation, softness, and optical defocus are different visual problems.
| FX | What shapes the result | Explore it for |
|---|---|---|
| Box Blur ↗ | Actual soft blur with box-kernel/Iterations and no visible mosaic cells. | When the task is softness or technical blur rather than graphic pixelation. |
| Gaussian Blur ↗ | Neutral smooth blur with H/V and channel adjustments. | When you need even softness without cell geometry. |
| Mosaic Blur | A Square/Hexagon/Triangle geometric grid that deliberately removes fine detail. | Privacy masking, explicit censorship, pixel-art language, and graphic transitions. |
| Lens Blur ↗ | Optical defocus with aperture/bokeh geometry. | When blur should resemble lens behavior rather than a privacy effect. |
07READ THE FAILURE
A weak mosaic usually fails through coverage, retained structure, or a misunderstood edge control.
01The face is still recognizable+
Check tracking and Window size first. If coverage is stable, make the cells coarser with Pixel Frequency and verify that Blend is not restoring the source. Do not try to solve privacy by changing Cell Shape alone.
02Awkward partial cells remain at the Window edge+
Check Whole Cells Only. It specifically limits the result to cells completely inside the Window. If enabling it narrows coverage too much, expand the mask rather than risking privacy.
03Triangle/Hexagon edges look jagged+
Compare Antialias Result on/off at 100% viewer scale. Do not confuse it with Aliasing: the latter concerns sampling inside the cell, not extra geometric edge cleanup.
04The grid is coarse but a digit is still inferable+
Adjust X/Y Offset and inspect Aspect: a critical stroke may sit along a cell boundary. Then recheck the whole track. For high-stakes confidentiality, consider opaque redaction rather than trying to push the effect harder.
05RGB is mosaicked but a transparent matte behaves differently+
Check Blur Alpha in the actual composite. If the problem remains, diagnose premultiplication and the alpha pipeline separately; Blur Alpha does not repair a poorly prepared matte.
06A creative transition flickers after export+
Check Antialias Result, Pixel Frequency animation speed, and the delivery codec. Very fine or rapidly changing geometric boundaries can interact with scaling and compression more strongly than they do in the Viewer.
Privacy is a whole-clip test
Do not approve the effect from one convincing setup frame. Review the start, end, fast head turns, motion blur, and moments when the subject approaches the Window edge.
Delivery can change readability
Scaling, sharpening, and compression change the appearance of a fine mosaic grid. Perform the final concealment check on the actual exported file and at the size viewers will see.
High stakes may require opaque redaction
Mosaic Blur is a visual effect, not cryptographic protection. If disclosure is unacceptable under any circumstances, opaque redaction or removing/replacing the source information before publication is safer.
08BEFORE YOU DELIVER
Certify the concealed information, not the slider position.
A Mosaic Blur value is not a security certificate. The accepted result is the exported image after tracking, scaling, compression, and the final delivery path.
09FAQ
The questions that prevent the most common Mosaic Blur mistakes.
Which control determines “pixel size”?
Pixel Frequency. It determines each mosaic cell’s size and the density of the resulting grid. Judge it by how much real information remains readable, not by the number itself.
Are Aliasing and Antialias Result the same thing?
No. Resolve’s manual describes Aliasing as controlling how tightly each cell samples the area underneath it. Antialias Result separately enables extra processing for cleaner lines between cells.
What does Whole Cells Only do?
It limits displayed cells to those completely inside a Power Window. It is a local Window-boundary behavior, not a mode for the outer frame edge.
Which Cell Shape is best for concealing a face?
Square is the most familiar and visually predictable option, but concealment strength depends mainly on cell size, stable Window/tracking, and full Blend. Hexagon or Triangle are not automatically safer.
Can I make censorship “softer” with Blend?
For privacy that is a poor choice: lowering Blend restores source detail. Establish sufficient Pixel Frequency and clean localization while keeping Blend full.
Should Blur Alpha be enabled?
Only when the alpha channel actually matters. On ordinary opaque footage it may be visually irrelevant; on keyed or transparent elements it affects transparency-edge processing.
Does Mosaic Blur guarantee confidentiality?
No. It is a visual effect. For highly sensitive data, opaque redaction or removing the information before publication is safer than relying on pixelation alone.
Sources and verification scope
Control meanings are anchored to Blackmagic Design documentation. The screenshots come from the supplied project archive. The interactive lab and node graph are teaching models and are explicitly not presented as Resolve renders or screenshots.
These page exercises were not live-certified by rendering inside Resolve in this container. Verify edition availability, small UI differences, and final production behavior in the installed build used for delivery.