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Image MIME Reference
HEIC-Sequence

HEVC Image Sequence (HEIF Container)

image/heic-sequence
VS

GIMP Image Format

image/x-xcf
XCF

A complete technical comparison of HEVC Image Sequence (HEIF Container) and GIMP Image Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

HEIC-Sequence wins on browser support

Feature Support

Feature HEIC-Sequence XCF
Transparency (Alpha) Yes Yes
Animation Support Yes Yes
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
HEVC Image Sequence (HEIF Container)
image/heic-sequence
Extension
.heics.heic
Container HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression Lossy / Lossless
Algorithm
HEVC (H.265)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit
Developed by Moving Picture Experts Group (MPEG) / Apple
Released 2017
Magic Bytes
XX XX XX XX 66 74 79 70 68 65 76 63
Full HEIC-Sequence reference →
GIMP Image Format
image/x-xcf
Extension
.xcf
Container GIMP Hierarchical Chunk Container
Compression None / RLE (Run-Length Encoding) / Zlib / Deflate (In newer GIMP versions)
Algorithm
NoneRLEZlib
Color Depth 8-bit per channel, 16-bit per channel, 32-bit floating point
Developed by Spencer Kimball, Peter Mattis, and the GIMP Development Team
Released 1995
Magic Bytes
67 69 6D 70 20 78 63 66
Full XCF reference →

Browser Support Comparison

Browser HEIC-Sequence XCF
Chrome Chrome
Firefox Firefox
Safari Safari
✓ 11+
Edge Edge
IE IE (Legacy)
HEIC-Sequence

HEIC-Sequence Strengths

  • Incredibly efficient storage for bursts and short animations compared to GIF or motion JPEG
  • Supports 16-bit color, HDR, and alpha channel transparency across all frames
  • Shares frame data blocks, meaning the base image and animation data are heavily optimized for space
Limitations
  • Zero support in web browsers outside the Apple ecosystem (Chrome, Firefox, Edge do not support it)
  • Heavily encumbered by HEVC patent pools, hindering open-source adoption
  • Complex container structure makes parsing and decoding difficult without specialized libraries
XCF

XCF Strengths

  • Preserves all non-destructive editing elements, layer hierarchies, masks, and alpha channels across GIMP sessions
  • Open and thoroughly documented specification within the open-source community, allowing third-party tools like Krita and ImageMagick to read project files
  • Reliable magic byte header prevents misidentification
Limitations
  • Massive file sizes because raw, unflattened layer bitmaps and masks are stored directly within the project archive
  • Completely proprietary to the GIMP ecosystem for deep editing; cannot be natively rendered or parsed by web browsers
  • Third-party software supporting XCF may occasionally struggle to render complex text layer adjustments or advanced layer blend modes identically to GIMP

When to choose which format

HEIC-Sequence
Use HEIC-Sequence when…
  • Apple Live Photos
  • Burst Photography
  • High-Quality Animations
  • Cinemagraphs
XCF
Use XCF when…
  • GIMP Native Project Archival
  • Layered Photo Editing and Graphic Design
  • Intermediary Asset Preparation for Export
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