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Image MIME Reference
HEIC-Sequence

HEVC Image Sequence (HEIF Container)

image/heic-sequence
VS

Kodak K25 Raw Image

image/x-kodak-k25
Kodak-K25

A complete technical comparison of HEVC Image Sequence (HEIF Container) and Kodak K25 Raw Image — 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 Kodak-K25
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes ✕ No
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 →
Kodak K25 Raw Image
image/x-kodak-k25
Extension
.k25
Container Proprietary Kodak Raw (TIFF-based variant)
Compression Uncompressed / Proprietary Lossless
Algorithm
Proprietary Kodak Compression
Color Depth 10-bit, 12-bit (Per Channel)
Developed by Eastman Kodak Company
Released 1996
Magic Bytes
Varies (Often resembles TIFF header 49 49 2A 00 or requires proprietary parsing)
Full Kodak-K25 reference →

Browser Support Comparison

Browser HEIC-Sequence Kodak-K25
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
Kodak-K25

Kodak-K25 Strengths

  • Historically significant format tied to the first digital camera to adopt CompactFlash memory
  • Preserves original raw sensor data, allowing modern demosaicing algorithms (via LibRaw) to extract much better image quality than 1996-era software could
Limitations
  • Completely obsolete and deeply proprietary, lacking modern raw format features found in DNG
  • Cannot be natively viewed in web browsers or standard operating system image viewers without specialized decoders
  • Subject to misidentification by automated MIME detection libraries due to structural similarities with standard TIFFs

When to choose which format

HEIC-Sequence
Use HEIC-Sequence when…
  • Apple Live Photos
  • Burst Photography
  • High-Quality Animations
  • Cinemagraphs
Kodak-K25
Use Kodak-K25 when…
  • Vintage Digital Photography Archival
  • Kodak DC25 Camera Restorations
  • Historical Imaging Research

More comparisons

HEIC-Sequence vs ACES → Kodak-K25 vs ACES → HEIC-Sequence vs APNG → Kodak-K25 vs APNG → HEIC-Sequence vs AVCI → Kodak-K25 vs AVCI → HEIC-Sequence vs AVCS → Kodak-K25 vs AVCS → HEIC-Sequence vs AVIF → Kodak-K25 vs AVIF → All comparisons →
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