Image MIME Reference
JNG
JPEG Network Graphics
image/x-jng
VS
Panasonic RAW Image
image/x-panasonic-raw
Panasonic-RAW-(RW2)
A complete technical comparison of JPEG Network Graphics and Panasonic RAW Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | JNG | Panasonic-RAW-(RW2) |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | Yes | Yes |
| ICC Color Profile | Yes | Yes |
JPEG Network Graphics
image/x-jng
Extension
.jng
Container
PNG-style Chunk Structure (JHDR, JDAT, IDAT, IEND)
Compression
Lossy (JPEG/DCT for color) / Lossless (Deflate for alpha mask)
Algorithm
JPEG (Discrete Cosine Transform)Deflate (LZ77)
Color Depth
8-bit, 12-bit, 24-bit (RGB), 32-bit (RGBA)
Developed by
MNG Development Group (Glenn Randers-Pehrson et al.)
Released
2001
Magic Bytes
8B 4A 4E 47 0D 0A 1A 0A
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
Browser Support Comparison
| Browser | JNG | Panasonic-RAW-(RW2) |
|---|---|---|
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
JNG
JNG Strengths
- Solved a massive technical hurdle in the early 2000s by combining high-compression lossy photographic data with crisp, 8-bit alpha transparency
- Utilized the highly robust, extensible chunk-based architecture of the PNG format
- Provided an excellent, bandwidth-saving alternative to massive 32-bit transparent PNGs for web design
Limitations
- Failed to achieve critical mass; browser vendors largely abandoned the MNG/JNG standard due to implementation complexity
- Completely obsolete today, having been superseded by natively supported, superior formats like WebP, AVIF, and HEIC
- Decoding requires a hybrid engine that can parse PNG chunks while simultaneously decoding a JPEG stream and a Deflate stream, complicating 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
JNG
Use JNG when…
- Embedded frames in MNG animations
- Historical web graphics requiring lossy compression with transparency
Panasonic-RAW-(RW2)
Use Panasonic-RAW-(RW2) when…
- Professional Digital Photography
- Non-destructive Image Post-Processing
- High Dynamic Range (HDR) Lumix Archival