Procreate archive and tiles

Savage Interactive does not publish the format. This page follows Silicate, an open source viewer that reads .procreate files, and marks what it does not establish.

Entry	Contents
`Document.archive`	The document: canvas, layer tree and settings, as an Apple keyed archive (below).
`QuickLook/Thumbnail.png`	A small preview.
`uuid/col~row.chunk`	One tile of a layer, a mask or the composite, LZO-compressed. The folder is the UUID of the layer.
`uuid/col~row.lz4`	The same tile, LZ4-compressed, as written by newer versions of Procreate.
`video/segments/segment-n.mp4`	The time-lapse recording, in parts.

Document.archive

A binary property list written by NSKeyedArchiver: the objects sit in a flat $objects array and refer to each other by index, and each object’s $class names its type. The root object is a SilicaDocument.

SilicaDocument

Key	Type	Meaning
`size`	size string	Canvas width and height in pixels.
`tileSize`	integer	Width and height of a tile in pixels.
`unwrappedLayers`	array	The layer tree: `SilicaLayer` and `SilicaGroup` objects.
`composite`	`SilicaLayer`	The flattened image, stored as a layer with its own tiles.
`name`	string	Document name.
`authorName`	string	Author.
`backgroundColor`	data	Four little-endian 32-bit floats: red, green, blue, alpha.
`backgroundHidden`	boolean	Whether the background colour is hidden (transparent background).
`strokeCount`	integer	Number of strokes painted.
`orientation`	integer	1 no rotation, 2 rotated 180°, 3 rotated 270° clockwise, 4 rotated 90° clockwise.
`flippedHorizontally`, `flippedVertically`	boolean	Canvas flips.

Other keys seen in the archive include layers, selectedLayer, primaryItem, mask, videoEnabled, SilicaDocumentArchiveDPIKey, SilicaDocumentArchiveUnitKey, SilicaDocumentTrackedTimeKey, SilicaDocumentVideoPurgedKey and SilicaDocumentVideoSegmentInfoKey; their values are not described.

SilicaLayer

Key	Type	Meaning
`UUID`	string	The layer’s ID, which is also the folder of its tiles.
`name`	string	Layer name.
`opacity`	float	0 to 1.
`hidden`	boolean	Hidden.
`clipped`	boolean	Clipping mask: drawn only where the layer below is.
`blend`	integer	Blend mode, below.
`extendedBlend`	integer	Blend mode in newer files; when present it overrides `blend`.
`mask`	`SilicaLayer`	A layer mask, with its own one-channel tiles.
`version`	integer	Layer version.

Other layer keys seen but not described: type, locked, preserve, private, contentsRect, contentsRectValid, transform, perspectiveAssisted, animationHeldLength, bundledImagePath, bundledMaskPath, bundledVideoPath, text and textPDF.

SilicaGroup

Key	Type	Meaning
`name`	string	Group name.
`isHidden`	boolean	Hidden.
`children`	array	The layers and groups inside.

Blend modes

Value	Mode	Value	Mode
0	Normal	14	Luminosity
1	Multiply	15	Hue
2	Screen	16	Saturation
3	Add	17	Soft light
4	Lighten	18	not known
5	Exclusion	19	Darken
6	Difference	20	Hard mix
7	Subtract	21	Vivid light
8	Linear burn	22	Linear light
9	Colour dodge	23	Pin light
10	Colour burn	24	Lighter colour
11	Overlay	25	Darker colour
12	Hard light	26	Divide
13	Colour

Tiles

The canvas is cut into tileSize squares: ceil(width / tileSize) columns and ceil(height / tileSize) rows. Tiles in the last column and row are only as wide and high as what is left of the canvas.
A tile file name gives its column and row, such as 3~1.chunk.
A colour tile decompresses to width × height × 4 bytes of 8-bit RGBA; Silicate’s documentation describes the colour as premultiplied by alpha. A mask tile decompresses to one byte per pixel.
.chunk files are raw LZO1X data. .lz4 files are LZ4 blocks in a framing of their own, with separate block types for compressed data, stored data and the end; each block may refer back to the bytes already decoded.

Unknowns

Blend mode 18, and the meaning of many archive keys listed above.
The exact magic numbers and header of the LZ4 block framing.
Whether row 0 is the top or the bottom of the canvas.
Text layers, reference layers, animation settings and brush data.

.PROCREATE File Format – Archive and tiles

Archive