Image MIME Reference
G3-Fax
Group 3 Fax Image
image/g3fax
VS
Tencent TAP Image
image/vnd.tencent.tap
Tencent-TAP
A complete technical comparison of Group 3 Fax Image and Tencent TAP Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | G3-Fax | Tencent-TAP |
|---|---|---|
| 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)
Tencent TAP Image
image/vnd.tencent.tap
Extension
.tap
Container
Proprietary Tencent Container
Compression
Unknown (Proprietary)
Algorithm
Unknown
Color Depth
Unknown
Developed by
Tencent (Registered by Ni Hui)
Released
2014
Magic Bytes
Unknown (Proprietary)
Browser Support Comparison
| Browser | G3-Fax | Tencent-TAP |
|---|---|---|
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
Tencent-TAP
Tencent-TAP Strengths
- Officially registered with IANA, ensuring a unique MIME type identifier for internal Tencent network routing and content negotiation
Limitations
- Completely undocumented and closed-source, making it impossible to decode or parse outside of Tencent's software
- Shares its file extension (.tap) with numerous other established legacy formats, leading to frequent automated file misidentification by Node/Python libraries
When to choose which format
G3-Fax
Use G3-Fax when…
- Telefacsimile (Fax) Transmission
- Internet Fax (T.37)
- Document Archiving
- Telephony Systems
Tencent-TAP
Use Tencent-TAP when…
- Internal Tencent Ecosystem Applications
- Proprietary Mobile or Gaming Assets