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Image MIME Reference
Panasonic-RAW-(RW2)

Panasonic RAW Image

image/x-panasonic-raw
VS

Portable Network Graphics (Legacy MIME)

image/x-png
PNG

A complete technical comparison of Panasonic RAW Image and Portable Network Graphics (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

PNG wins on browser support

Feature Support

Feature Panasonic-RAW-(RW2) PNG
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
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 →
Portable Network Graphics (Legacy MIME)
image/x-png
Extension
.png
Container PNG Chunk Structure (IHDR, IDAT, IEND)
Compression Deflate (Lossless)
Algorithm
Deflate (LZ77)
Color Depth 1-bit to 16-bit (Grayscale), 8-bit (Indexed Palette), 24-bit (True Color), 32-bit (True Color with Alpha), 48-bit (High Color), 64-bit (High Color with Alpha)
Developed by PNG Development Group
Released 1996
Magic Bytes
89 50 4E 47 0D 0A 1A 0A
Full PNG reference →

Browser Support Comparison

Browser Panasonic-RAW-(RW2) PNG
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
IE IE (Legacy)
✕
✓
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
PNG

PNG Strengths

  • The underlying format provides flawless, lossless compression and perfect 8-bit alpha channel transparency
  • Universally supported by every modern operating system, image editor, and web browser
Limitations
  • The 'image/x-png' string is an obsolete vendor quirk that forces backend developers to write redundant normalization logic in file upload scripts
  • If left unnormalized, strict MIME validators or content security policies on modern systems may incorrectly reject valid PNG files

When to choose which format

Panasonic-RAW-(RW2)
Use Panasonic-RAW-(RW2) when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Lumix Archival
PNG
Use PNG when…
  • Legacy Internet Explorer File Uploads
  • Older ASP/PHP Web Applications
  • Lossless Web Graphics

More comparisons

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