Block Mosaic

Rebuilds the picture as a tiled wall: small tiles mixed with larger ones, separated by grout lines.

Group: Pixel & Mosaic · How to add an effect

A detail of the harbour houses, left half as it is; right half rebuilt from small and large square tiles separated by thin dark grout lines — Left: original. Right: the default settings. A detail, enlarged.

Use it for: a tiled-wall or bathroom-mosaic look · a projection that reads as a wall of screens · a restless, flickering mosaic (with Speed).

Tile Size – the size of the small tiles, measured like Pixelate’s Pixel Size (on a full-HD picture).
Grout Width / Grout Color – the lines between the tiles; 0 leaves them out.
Speed – how many times per second the large tiles are drawn anew at random; 0 (the default) keeps them still.
Amount – mixes the tiles with the original picture.

Tip: a light Grout Color on a dark stage reads like a tiled wall; set Speed to the tempo of the music for a mosaic that changes on the beat.

Controls

Control	Range	Default
Tile Size	4 to 128	22
Grout Width	0 to 12	2
Grout Color	a colour	`#111827`
Speed	0 to 5	0
Amount	0 to 1	1

Node setup

Block Mosaic is Pixelate’s recipe with a Large Tiles folder before the grid, a Grout folder after it and Mix with Original for Amount.

Part of Block Mosaic's Large Tiles folder: Floor of the Large Grid Position gives the Large Tile Index; Random (Hash) turns it into Group Random; Shuffle Step times Shuffle Rate, then Fraction, gives the Shuffle Seed; Combine Vector and Add mix group and seed into the Shuffled Key; a second Random (Hash) turns it into a number; Greater Than compares it with Large Threshold 0.68; a Switch picks Tile (px) or Large Tile (px) — Part of the Large Tiles folder. Green cards stand for values the excerpt does not show: Tile (px) comes from Cell Size, the others sit in this folder too, beside the time and Speed nodes that count the Shuffle Step. Large Threshold (0.68) decides how many tile groups become one large tile.

Floor numbers every square group of 2 × 2 tiles, and Random (Hash) gives each group its own random number. The Shuffle Step counts up Speed times per second; Multiply and Fraction turn it into a Shuffle Seed that jumps to a new value at every step. Combine Vector and Add mix group and seed, and the second Random (Hash) turns that into a number between 0 and 1, new for every group at every step. Greater Than makes a large tile wherever it is above Large Threshold: about one group in three. Switch hands the grid the large or the small tile size.

Remix: select Large Threshold and lower it in the node inspector, for example to 0.4, so more than half of the groups become large tiles; 1 turns them off.

Technical details

Large tiles. Each 2 × 2 group is hashed, a seed of fract(step × (0.618, 0.755)) is added and the result hashed again; a group is large above 0.68. The step is floor(time × Speed) on the timeline clock, so seeking and the export repeat it.
Grout is split over both sides of every tile edge, with a one-pixel soft edge. In a small preview thin grout lines look softer than in the export.
Small sizes. A Tile Size below two rendered pixels is raised to 2 pixels, and the inspector says so.
Saved projects made with the earlier Block Mosaic open with the 1080p-based sizes, the centred grid and averaged colours, and keep a 1-pixel grout in its darker colour.

Grid, sizes and transparency: Pixel & Mosaic. Recipes: Effect system: editable mirror, split and pixel graphs. Nodes: Node Catalog.