Image MIME Reference
DNG
Adobe Digital Negative
image/x-adobe-dng
VS
PTI Image (Personal/Vanity Tree)
image/prs.pti
PTI
A complete technical comparison of Adobe Digital Negative and PTI Image (Personal/Vanity Tree) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DNG | PTI |
|---|---|---|
| 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
PTI Image (Personal/Vanity Tree)
image/prs.pti
Extension
.pti
Container
Proprietary
Compression
Unknown / Proprietary
Algorithm
Unknown
Color Depth
Unknown
Developed by
Jürn Laun
Released
1999
Magic Bytes
Unknown
Browser Support Comparison
| Browser | DNG | PTI |
|---|---|---|
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
PTI
PTI Strengths
- Provided a registered MIME type namespace for a specific application's proprietary image format without conflicting with standard web types
Limitations
- Completely undocumented and unsupported in modern ecosystems
- Zero web browser compatibility
- Falls into the 'vanity' tree, making it irrelevant for standard cross-platform data exchange
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
PTI
Use PTI when…
- Legacy Application Specific Workflows
- Proprietary Image Storage