File Formats

OpenGPEX supports a wide range of image formats for import and export, with special handling for the native .gpex project format.

Supported Import Formats

Format	Extension	Notes
JPEG	.jpg, .jpeg	Most common photo format
PNG	.png	Lossless with alpha support
WebP	.webp	Modern lossy/lossless format
AVIF	.avif	Next-gen compression
GIF	.gif	First frame extracted
BMP	.bmp	Uncompressed bitmap
SVG	.svg	Rasterized on import
HEIC/HEIF	.heic, .heif	Via WASM decoder (Apple photos)

Export Formats

Format	Encoder	Quality Range
JPEG	Browser native	1-100
PNG	Browser native	Lossless
WebP	Browser native	1-100
AVIF	WASM (`avif_enc.wasm`)	1-100

Native Format: .gpex

The .gpex format is a ZIP archive containing the full project state:

project.gpex (ZIP)
├── manifest.json       # Version, dimensions, metadata
├── state.json          # Serialized EditorState (frames, layers)
├── assets/             # CAS-stored image blobs
│   ├── sha256-abc123.png
│   └── sha256-def456.jpg
└── thumbnails/         # Preview images
    └── preview.webp

Key Features:

Self-contained — All assets bundled, no external dependencies
Resumable — Full undo history can optionally be included
Portable — Standard ZIP, inspectable with any archive tool

EXIF Preservation

When exporting, OpenGPEX preserves original EXIF metadata (camera model, GPS, date) from the source image, unless the user explicitly opts to strip it for privacy.

WASM Encoders

Performance-critical formats use WebAssembly encoders running inside Web Workers:

Encoder	Speed vs JS	File Size Savings
AVIF (WASM)	10-50× faster	30-50% smaller than JPEG

WASM modules are lazy-loaded — only downloaded when the user first exports in that format.

Next Steps

Engine & Workers — WASM integration details
Rendering Pipeline — Export pipeline architecture
Cloud Storage — Saving .gpex to the cloud

Last updated: 2026-06-14