Image MIME Reference
DNG
Adobe Digital Negative
image/x-adobe-dng
VS
PWG Raster Format
image/pwg-raster
PWG-Raster
A complete technical comparison of Adobe Digital Negative and PWG Raster Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DNG | PWG-Raster |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
Adobe Digital Negative
image/x-adobe-dng
Extension
.dng
Container
TIFF/EP
Compression
Lossless JPEG / Deflate / Lossy JPEG (DNG 1.4+)
Algorithm
Lossless JPEG (Standard)Lossy JPEG (Compression option)Uncompressed
Color Depth
12-bit, 14-bit, 16-bit, 32-bit (Floating Point HDR)
Developed by
Adobe Systems
Released
2004
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
PWG Raster Format
image/pwg-raster
Extension
.pwg.ras
Container
CUPS Raster v2 Container
Compression
PackBits (Run-Length Encoding)
Algorithm
PackBits (Apple RLE variant)
Color Depth
1-bit (Monochrome/K), 8-bit (Grayscale), 24-bit (sRGB / Adobe RGB), 32-bit (CMYK)
Developed by
IEEE-ISTO Printer Working Group (PWG)
Released
2011
Magic Bytes
52 61 53 32
Browser Support Comparison
| Browser | DNG | PWG-Raster |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
DNG
DNG Strengths
- Openly documented specification guarantees long-term archival accessibility, freeing photographers from proprietary manufacturer lock-in
- Lossless compression algorithms often result in files 15-20% smaller than uncompressed proprietary raw formats
- Natively supported by modern smartphone operating systems (iOS and Android) for high-end mobile photography
Limitations
- Conversion from proprietary raw to DNG takes processing time and can strip specific, proprietary manufacturer metadata (like active D-Lighting or in-camera lens corrections)
- File sizes are massive compared to standard JPEGs or HEIC files
- Cannot be rendered natively in web browsers without server-side processing or WebAssembly decoders
PWG-Raster
PWG-Raster Strengths
- The undisputed global standard for modern, driverless printing environments, eliminating the nightmare of installing manufacturer-specific print drivers
- Extremely lightweight to decode on embedded hardware, requiring minimal RAM buffers on the printer side
- Strict color space and resolution rules guarantee that the printed output will successfully process without syntax errors
Limitations
- Generates massive file sizes and network payloads compared to vector-based formats like PDF or PostScript, as every page is fully rasterized at 300+ DPI before transmission
- No support for native rendering in web browsers, image viewers, or graphic design software without specialized CUPS developer tools
- Cannot store complex metadata, vector text, or layers
When to choose which format
DNG
Use DNG when…
- Digital Photography Archival
- Mobile Raw Capture (iOS ProRAW / Android Camera2 API)
- Cross-Platform Raw Editing Workflows
PWG-Raster
Use PWG-Raster when…
- Driverless Network Printing (IPP Everywhere)
- Apple AirPrint and Mopria Print Service Pipelines
- CUPS (Common UNIX Printing System) Spooling