Image MIME Reference
G3-Fax
Group 3 Fax Image
image/g3fax
VS
North American Presentation Level Protocol Syntax
image/naplps
NAPLPS
A complete technical comparison of Group 3 Fax Image and North American Presentation Level Protocol Syntax — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | G3-Fax | NAPLPS |
|---|---|---|
| Transparency (Alpha) | ✕ No | ✕ No |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | Yes |
| 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)
North American Presentation Level Protocol Syntax
image/naplps
Extension
.nap.naplps
Container
NAPLPS Byte Stream
Compression
Uncompressed (Tokenized ASCII Commands)
Algorithm
None (Coordinate encoding)
Color Depth
16-color palette (Indexed from larger color spaces)
Developed by
ANSI / CSA (Based on Canadian CRC's Telidon)
Released
1983
Magic Bytes
1B (Variable / ESC sequences)
Browser Support Comparison
| Browser | G3-Fax | NAPLPS |
|---|---|---|
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
NAPLPS
NAPLPS Strengths
- Extremely bandwidth-efficient, enabling colorful graphical interfaces over early 300 baud dial-up connections
- Resolution-independent vector scaling allowed the exact same file to be displayed accurately on varied early PC monitors and television sets
Limitations
- Completely obsolete and unsupported by modern web technologies
- Relies heavily on stateful parsing and terminal emulators rather than straightforward file decoding
- Easily misidentified by MIME sniffers as plain text or generic binary streams due to the lack of a standardized file header
When to choose which format
G3-Fax
Use G3-Fax when…
- Telefacsimile (Fax) Transmission
- Internet Fax (T.37)
- Document Archiving
- Telephony Systems
NAPLPS
Use NAPLPS when…
- 1980s Videotex Services
- Prodigy Online Service Graphics
- Historical BBS Terminal Graphics
- Legacy Teletext Broadcasts