MosaicBlur

MosaicBlur deliberately removes fine spatial detail by grouping the image into repeating cells. Unlike Gaussian or Box Blur it does not aim to make neighboring pixels smoothly softer; the visual language is a discrete geometric grid with visible topology.

The processing model is easiest to read in stages: Image Input supplies the RGBA frame, Pixel Frequency sets grid density, Cell Shape selects topology, Aliasing changes how the cell samples the image underneath, X/Y Offset and Aspect place the lattice, and Antialias Result plus Whole Cells Only handle separate aspects of the final edge/boundary behavior.

Pixel Frequency is the primary coarseness control. Blackmagic describes it as adjusting the size of each mosaic pixel and therefore the density/resolution of the resulting grid. In practice a higher frequency gives more, smaller cells and preserves more recognizable structure; a lower frequency produces larger blocks and stronger loss of detail.

Cell Shape is one authored control with three options: Square, Hexagon and Triangle. Square is conventional pixelation, Hexagon creates a honeycomb pattern, and Triangle creates a sharper angular lattice. The three options should not be counted as three additional Inspector controls.

Aliasing and Antialias Result are different operations. Blackmagic defines Aliasing in terms of how tightly each cell samples the area underneath it. Antialias Result is a separate checkbox that performs additional processing for cleaner lines between cells. Treating Aliasing as merely another edge-smoothing slider collapses two distinct stages into one.

X Offset and Y Offset move the mosaic lattice relative to the image. They do not move the source and they do not track a subject. When a face, plate or screen moves, track the Effect Mask; use the offsets for lattice phase, alignment or intentional graphic animation.

Aspect changes cell proportions. On Square it can turn a neutral square lattice into horizontal or vertical blocks; on Hexagon/Triangle it changes the rhythm of the geometry. This changes the sampling grid rather than transforming Image Input itself.

Antialias Result is best judged on diagonal Hexagon/Triangle boundaries and in playback. The checkbox does not change grid density or Cell Shape and it is not a synonym for Aliasing; it adds a result-cleanup stage for cell boundaries.

Whole Cells Only is documented in window terminology: only cells completely inside a window are shown. On this Fusion page it should be treated as a boundary rule, not as a generic full-frame crop. Its exact interaction with a particular Effect Mask is worth A/B testing in the target build, especially for privacy work.

Effect Mask is a separate spatial input. It limits where the processed MosaicBlur contributes but does not become the source image, does not define cell color and does not move the lattice with a subject. Track the mask with enough margin for motion and motion blur.

For privacy work, aesthetics are secondary. Verify that a face, plate, document or text is actually unreadable at 100%, after resize and in the final codec. A fine mosaic can look obviously pixelated while still preserving identifying structure.

There is also a product-surface boundary worth documenting: the current Resolve FX Blur manual describes Blur Alpha for Mosaic Blur, but the captured Resolve 21 Fusion Inspector used by this encyclopedia does not expose it. This page therefore records only the eight controls confirmed by the Fusion capture instead of importing a control from another UI surface without live evidence.