Image MIME Reference
PNG
Portable Network Graphics (Legacy MIME)
image/x-png
VS
Sony SRF Raw Image
image/x-sony-srf
Sony-SRF
A complete technical comparison of Portable Network Graphics (Legacy MIME) and Sony SRF Raw Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
PNG wins on browser support
Feature Support
| Feature | PNG | Sony-SRF |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | Yes |
| ICC Color Profile | Yes | Yes |
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
Sony SRF Raw Image
image/x-sony-srf
Extension
.srf
Container
TIFF-based (Proprietary)
Compression
Uncompressed
Algorithm
None
Color Depth
12-bit (Per Channel)
Developed by
Sony Corporation
Released
2003
Magic Bytes
49 49 2A 00
Browser Support Comparison
| Browser | PNG | Sony-SRF |
|---|---|---|
Chrome
|
✓ 1
|
✕ |
Firefox
|
✓ 1
|
✕ |
Safari
|
✓ 1
|
✕ |
Edge
|
✓ 12
|
✕ |
IE (Legacy)
|
✓
|
✕ |
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
Sony-SRF
Sony-SRF Strengths
- Retains perfectly raw, unprocessed sensor data from legacy early-2000s cameras, allowing modern raw processors to extract much better dynamic range and color than the camera's original internal JPEG engine could
- Utilizes a standard TIFF container structure, ensuring broad compatibility with community-maintained open-source decoding libraries like LibRaw
Limitations
- Completely obsolete format that has long been abandoned in favor of ARW
- MIME detection via magic bytes is unreliable due to TIFF header spoofing, requiring deeper EXIF inspection for accurate routing
- Cannot be natively viewed in web browsers or standard operating system image viewers without specialized decoders
When to choose which format
PNG
Use PNG when…
- Legacy Internet Explorer File Uploads
- Older ASP/PHP Web Applications
- Lossless Web Graphics
Sony-SRF
Use Sony-SRF when…
- Legacy Sony Cyber-shot Photography
- Non-destructive Image Post-Processing
- Early 2000s Raw Imaging Archival