What Is a .XCF File?

GIMP Image (.xcf)

Overview

XCF (eXperimental Computing Facility, named after the Berkeley lab where GIMP began) is the native project format of GIMP, the free image editor. An .xcf file keeps everything an editing session needs: every layer with its own blend mode and opacity, layer groups, masks, channels, paths, selections, guides, text layers that remain editable, and the full undo-relevant state.

It is to GIMP what .psd is to Photoshop: the working file you save while editing, not the image you send to anyone. Exporting to PNG or JPEG flattens all of that into pixels.

Technical Specifications

• MIME Type: image/x-xcf
• File Extensions: .xcf; .xcf.gz, .xcf.bz2 and .xcf.xz for compressed variants GIMP reads directly
• Category: Image
• Developer: the GIMP project
• Introduced: 1996, with GIMP 0.54
• Current version: XCF v011 and later (GIMP 2.10), v012+ (GIMP 3.0)
• Magic bytes: 67 69 6D 70 20 78 63 66 20 (gimp xcf ) followed by the version

Identification

00000000  67 69 6d 70 20 78 63 66  20 76 30 31 31 00 00 00  |gimp xcf v011...|
00000010  07 80 00 00 04 38 00 00  00 00 00 00 00 ...        |.....8..........|

The 9-byte gimp xcf signature is followed by a 4-byte version string (file for the original format, v001 to v012 and beyond) and a null byte. Then come the canvas width, height and base colour type. Compressed variants start with the gzip, bzip2 or xz magic instead and must be decompressed to reveal this.

File Structure

XCF file
├── Header             signature, version, width, height, base type, precision (v004+)
├── Image properties   compression, resolution, colour map, guides, parasites (metadata blobs)
├── Layer pointers     offsets to each layer
├── Channel pointers   offsets to each channel (alpha, masks, selection)
└── Hierarchies        per layer: tiles of 64 x 64 pixels, RLE- or zlib-compressed

Pixel data is stored in 64 x 64 tiles, which is how GIMP edits very large images without loading everything. Layers can be larger than the canvas and offset anywhere. Parasites are named binary blobs that hold things like Exif data, text-layer markup and plugin settings.

GIMP 2.10 added high bit depth (16 and 32-bit integer and float per channel) and linear-light precision, which older GIMP versions cannot read. Files saved by 2.10 or 3.0 need a matching or newer GIMP.

History and Development

XCF appeared with the first public GIMP in 1996 and has been extended rather than replaced ever since. It was never designed as an interchange format, and the GIMP developers have said so: it is a serialisation of GIMP's internal image model, which is why other applications support it only partially.

A formal specification was written and is maintained in the GIMP source tree, which allowed ImageMagick, Krita, Darktable and a few others to read at least the composited image.

Common Use Cases

• Work in progress in GIMP: anything with layers, masks or editable text
• Source files for icons, mockups, textures and photo retouching done in GIMP
• Archival of the editable version alongside an exported PNG or JPEG
• Collaboration between GIMP users, since the file carries the full edit state

How to Open an XCF File

GIMP (all platforms)

GIMP is free and the only application that opens XCF with full fidelity. Download it for Windows, macOS or Linux from gimp.org; it is in every Linux repository and in Homebrew (brew install --cask gimp). File, Open, or drag the file onto the window.

A file that opens with a warning about an unsupported version was saved by a newer GIMP; update GIMP.

Without GIMP

• Krita imports XCF with layers (reasonably well for ordinary layer stacks).
• Darktable and RawTherapee open XCF as a flattened image for editing.
• ImageMagick: magick file.xcf -flatten file.png extracts the composite.
• XnView MP and IrfanView (with plugins) display the flattened image.
• Photoshop does not open XCF. Export from GIMP to PSD first.
• Online: Photopea opens XCF with layers in a browser.

Inspecting without opening

file image.xcf
# image.xcf: GIMP XCF image data, version 011, 1920 x 1080, RGB Color

magick identify image.xcf

How to Convert an XCF File

Export a finished image from GIMP

File, Export As (Ctrl+Shift+E), choose PNG, JPEG, WebP, TIFF or any other format. Export flattens the visible layers into one image and leaves the XCF untouched. Save and Save As only ever write XCF; this split confuses newcomers but protects the editable version.

Convert to PSD for Photoshop

File, Export As, choose .psd. Layers, masks, opacity and most blend modes survive; GIMP-specific features (layer groups in older versions, some modes) may flatten or change.

Command line

# Flattened composite to PNG
magick file.xcf -flatten file.png

# Each layer as a separate PNG
magick file.xcf layer_%02d.png

# Batch export with GIMP itself, headless
gimp -i -b '(let* ((img (car (gimp-file-load RUN-NONINTERACTIVE "in.xcf" "in.xcf"))) (lay (car (gimp-image-merge-visible-layers img CLIP-TO-IMAGE)))) (gimp-file-save RUN-NONINTERACTIVE img lay "out.png" "out.png"))' -b '(gimp-quit 0)'

For large batches, a Python-Fu or GIMP 3 Python script is easier to maintain than Script-Fu one-liners.

Compressing

GIMP saves .xcf.gz or .xcf.xz if you name the file that way, and reads them back transparently. Since GIMP 2.10 the format uses zlib tile compression by default, so the external gzip adds little; xz still helps for archives.

Advantages

• Complete fidelity for GIMP projects: nothing is lost between sessions.
• Open format with a published specification and a free editor.
• High bit depth and linear light since 2.10.
• Tiled storage keeps huge images workable.

Limitations

• Effectively GIMP-only for anything beyond the flattened image.
• Large files: layers are stored in full, and compression is modest.
• Version coupling: newer GIMP files do not open in older GIMP.
• Not for delivery: browsers, phones and most software cannot display it.

Related Formats

• PSD: Photoshop's equivalent, and the format to export to for Adobe users.
• PNG: the usual lossless export.
• TIFF: for high bit depth and print.
• WEBP and JPEG: for web delivery.