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Image MIME Reference
HEJ2K

JPEG 2000 Image (HEIF Container)

image/hej2k
VS

JPEG 2000 Codestream

image/j2c
J2C

A complete technical comparison of JPEG 2000 Image (HEIF Container) and JPEG 2000 Codestream — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature HEJ2K J2C
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading Yes Yes
HDR Support Yes Yes
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG 2000 Image (HEIF Container)
image/hej2k
Extension
.hej2
Container HEIF / ISOBMFF (ISO/IEC 15444-16)
Compression Lossy / Lossless
Algorithm
JPEG 2000HTJ2K
Color Depth 8-bit, 10-bit, 12-bit, 16-bit
Developed by ISO/IEC JTC 1 / ITU-T
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 32 6B 69
Full HEJ2K reference →
JPEG 2000 Codestream
image/j2c
Extension
.j2c.j2k.jpc
Container None (Raw Bitstream)
Compression JPEG 2000 (Discrete Wavelet Transform) / Lossless / Lossy
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit (Per Channel)
Developed by Joint Photographic Experts Group (JPEG)
Released 2000
Magic Bytes
FF 4F FF 51
Full J2C reference →

Browser Support Comparison

Browser HEJ2K J2C
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
HEJ2K

HEJ2K Strengths

  • Brings the extensive capabilities of the HEIF container (like EXIF/XMP, thumbnails, and depth maps) to JPEG 2000
  • Supports mathematically lossless compression via wavelet transformation
  • High scalability and progressive decoding out of the box
Limitations
  • Extremely limited software support outside of niche industries
  • Zero native compatibility with web browsers
  • High computational complexity compared to simpler formats like JPEG or PNG
J2C

J2C Strengths

  • Provides state-of-the-art wavelet compression for high-end professional workflows (Digital Cinema)
  • Allows for highly efficient progressive decoding (by resolution or quality layer) natively within the stream
  • Supports lossless mathematical compression and high bit-depths (up to 16-bit per channel) natively
Limitations
  • Lacks a standard container to store color space info or metadata, requiring external systems (like MXF or DICOM) to map colors correctly
  • Extremely computationally expensive to encode and decode compared to standard DCT-based JPEG
  • Zero web browser support

When to choose which format

HEJ2K
Use HEJ2K when…
  • Medical Imaging
  • Geospatial Data
  • Scientific Archiving
J2C
Use J2C when…
  • Digital Cinema Packages (DCP)
  • Medical Imaging (DICOM Payloads)
  • Professional Broadcast and Archiving
  • Embedded Hardware Encoding

More comparisons

HEJ2K vs ACES → J2C vs ACES → HEJ2K vs APNG → J2C vs APNG → HEJ2K vs AVCI → J2C vs AVCI → HEJ2K vs AVCS → J2C vs AVCS → HEJ2K vs AVIF → J2C vs AVIF → All comparisons →
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