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Image MIME Reference
HEIF-Sequence

High Efficiency Image File Format Sequence

image/heif-sequence
VS

Panasonic RAW Image

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

A complete technical comparison of High Efficiency Image File Format Sequence and Panasonic RAW Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature HEIF-Sequence Panasonic-RAW-(RW2)
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
High Efficiency Image File Format Sequence
image/heif-sequence
Extension
.heifs.heif.hif
Container HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression Lossy / Lossless
Algorithm
Codec Agnostic (HEVC, AVC, JPEG, AV1)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit
Developed by Moving Picture Experts Group (MPEG)
Released 2015
Magic Bytes
XX XX XX XX 66 74 79 70 6D 73 66 31
Full HEIF-Sequence 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 HEIF-Sequence Panasonic-RAW-(RW2)
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
HEIF-Sequence

HEIF-Sequence Strengths

  • Codec-agnostic container allows for extreme flexibility when storing multi-frame photographic data
  • Maintains the space-saving benefits of ISOBMFF shared frame data blocks
  • Excellent for archiving computational photography workloads like exposure brackets or focal stacks
Limitations
  • Codec ambiguity means a decoder might be able to parse the container but fail to decode the underlying pixels
  • Zero native web browser support
  • Complex container structure requires specialized parsing libraries to extract individual frames
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

HEIF-Sequence
Use HEIF-Sequence when…
  • Burst Photography
  • Focal Stacking
  • Exposure Bracketing
  • Time-Lapse Data
Panasonic-RAW-(RW2)
Use Panasonic-RAW-(RW2) when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Lumix Archival

More comparisons

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