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Image MIME Reference
HSJ2

JPEG 2000 Image Sequence (Obsolete)

image/hsj2
VS

Panasonic RAW Image

image/x-panasonic-raw
Panasonic-RAW-(RW2)

A complete technical comparison of JPEG 2000 Image Sequence (Obsolete) and Panasonic RAW Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature HSJ2 Panasonic-RAW-(RW2)
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading Yes ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
JPEG 2000 Image Sequence (Obsolete)
image/hsj2
Extension
.hsj2
Container HEIF / ISOBMFF (ISO/IEC 15444-16 Obsolete)
Compression Lossy / Lossless
Algorithm
Motion JPEG 2000 (ISO/IEC 15444-3)
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 68 73 6A 32
Full HSJ2 reference →
Panasonic RAW Image
image/x-panasonic-raw
Extension
.raw.rw2
Container TIFF-based (Proprietary)
Compression Uncompressed / Panasonic Proprietary Lossless
Algorithm
NoneProprietary Lossless
Color Depth 12-bit (Per Channel), 14-bit (Per Channel), 16-bit (Per Channel - High-res mode)
Developed by Panasonic Corporation
Released 2004
Magic Bytes
Older RAW: 49 49 2A 00 | Newer RW2: 49 49 55 00
Full Panasonic-RAW-(RW2) reference →

Browser Support Comparison

Browser HSJ2 Panasonic-RAW-(RW2)
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
HSJ2

HSJ2 Strengths

  • Historically attempted to combine Motion JPEG 2000 sequences with the flexible metadata capabilities of the HEIF container
  • Supported mathematically lossless compression and scalable wavelet decoding
Limitations
  • Officially deprecated by the standardization body (ISO/IEC JTC 1)
  • Completely superseded by image/hej2k, rendering hsj2 files obsolete for any new development or archiving
  • Zero web browser compatibility and negligible modern software support
Panasonic-RAW-(RW2)

Panasonic-RAW-(RW2) Strengths

  • Retains maximum sensor data, allowing significant recovery of highlights and shadows compared to in-camera JPEGs
  • Modern RW2 files embed proprietary lens correction profiles (distortion, vignetting, chromatic aberration) that raw converters can automatically apply
  • The unique 'IIU' signature on RW2 files makes programmatic identification extremely reliable compared to other TIFF-spoofing raw formats
Limitations
  • Proprietary format requires continuous updates to third-party processing engines whenever Panasonic releases a new Lumix camera
  • Produces very large file sizes, particularly when using Panasonic's High-Resolution multi-shot modes
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts

When to choose which format

HSJ2
Use HSJ2 when…
  • Legacy Archival
  • Deprecated Workflows
Panasonic-RAW-(RW2)
Use Panasonic-RAW-(RW2) when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Lumix Archival

More comparisons

HSJ2 vs ACES → Panasonic-RAW-(RW2) vs ACES → HSJ2 vs APNG → Panasonic-RAW-(RW2) vs APNG → HSJ2 vs AVCI → Panasonic-RAW-(RW2) vs AVCI → HSJ2 vs AVCS → Panasonic-RAW-(RW2) vs AVCS → HSJ2 vs AVIF → Panasonic-RAW-(RW2) vs AVIF → All comparisons →
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