Image MIME Reference
G3-Fax
Group 3 Fax Image
image/g3fax
VS
SealedMedia SoftSeal GIF
image/vnd.sealedmedia.softseal.gif
SoftSeal-GIF
A complete technical comparison of Group 3 Fax Image and SealedMedia SoftSeal GIF — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | G3-Fax | SoftSeal-GIF |
|---|---|---|
| Transparency (Alpha) | ✕ No | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Group 3 Fax Image
image/g3fax
Extension
.g3
Container
Raw Bitstream
Compression
Lossless (CCITT Group 3)
Algorithm
CCITT Group 3 (Modified Huffman / READ)
Color Depth
1-bit (Monochrome)
Developed by
CCITT (now ITU-T) / IETF
Released
1980
Magic Bytes
None (Raw Bitstream)
SealedMedia SoftSeal GIF
image/vnd.sealedmedia.softseal.gif
Extension
.sgif.sealed-gif
Container
SealedMedia SoftSeal Wrapper
Compression
Encrypted Payload (LZW)
Algorithm
AES EncryptionLZW (Internal GIF payload)
Color Depth
Encrypted Payload (Historically up to 8-bit Indexed)
Developed by
SealedMedia (Acquired by Oracle Corporation)
Released
Late 1990s
Magic Bytes
Unknown (Proprietary SealedMedia Container)
Browser Support Comparison
| Browser | G3-Fax | SoftSeal-GIF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
G3-Fax
G3-Fax Strengths
- Extremely efficient compression for 1-bit black-and-white text and line art
- Standardized via RFC 1494 for email and internet fax transmission
- Low bandwidth requirements
Limitations
- Raw format lacks metadata (such as image width and resolution), requiring out-of-band information to decode accurately
- Strictly limited to 1-bit monochrome imagery
- Zero native web browser support
SoftSeal-GIF
SoftSeal-GIF Strengths
- Provided robust, persistent security that traveled with the file, ensuring images could not be leaked even if sent outside the corporate firewall
- Enabled dynamic revocation, meaning administrators could instantly kill access to a file globally
Limitations
- Completely proprietary and dependent on an active authentication server; if the DRM server dies, the image is permanently locked
- Zero support in modern operating systems, web browsers, or standard image editing suites without heavy enterprise client installations
- Often caused massive friction for legitimate end-users trying to view documents
When to choose which format
G3-Fax
Use G3-Fax when…
- Telefacsimile (Fax) Transmission
- Internet Fax (T.37)
- Document Archiving
- Telephony Systems
SoftSeal-GIF
Use SoftSeal-GIF when…
- Enterprise Information Rights Management (IRM)
- Secure Distribution of Corporate Assets
- Revocable Medical, Legal, or Financial Imaging