Image MIME Reference
JNG
JPEG Network Graphics
image/x-jng
VS
AutoCAD Slide
image/vnd.sld
SLD
A complete technical comparison of JPEG Network Graphics and AutoCAD Slide — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | JNG | SLD |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
JPEG Network Graphics
image/x-jng
Extension
.jng
Container
PNG-style Chunk Structure (JHDR, JDAT, IDAT, IEND)
Compression
Lossy (JPEG/DCT for color) / Lossless (Deflate for alpha mask)
Algorithm
JPEG (Discrete Cosine Transform)Deflate (LZ77)
Color Depth
8-bit, 12-bit, 24-bit (RGB), 32-bit (RGBA)
Developed by
MNG Development Group (Glenn Randers-Pehrson et al.)
Released
2001
Magic Bytes
8B 4A 4E 47 0D 0A 1A 0A
AutoCAD Slide
image/vnd.sld
Extension
.sld
Container
AutoCAD Slide Container
Compression
Uncompressed (Vector Instructions)
Algorithm
None
Color Depth
8-bit (AutoCAD Indexed Color)
Developed by
Autodesk, Inc.
Released
1980s
Magic Bytes
41 75 74 6F 43 41 44 20 53 6C 69 64 65 0D 0A 1A 00
Browser Support Comparison
| Browser | JNG | SLD |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
JNG
JNG Strengths
- Solved a massive technical hurdle in the early 2000s by combining high-compression lossy photographic data with crisp, 8-bit alpha transparency
- Utilized the highly robust, extensible chunk-based architecture of the PNG format
- Provided an excellent, bandwidth-saving alternative to massive 32-bit transparent PNGs for web design
Limitations
- Failed to achieve critical mass; browser vendors largely abandoned the MNG/JNG standard due to implementation complexity
- Completely obsolete today, having been superseded by natively supported, superior formats like WebP, AVIF, and HEIC
- Decoding requires a hybrid engine that can parse PNG chunks while simultaneously decoding a JPEG stream and a Deflate stream, complicating software support
SLD
SLD Strengths
- Allowed for instantaneous loading of highly complex architectural and engineering blueprints on low-memory MS-DOS systems
- Easy-to-parse binary structure containing simple opcodes for drawing vectors and polygons
Limitations
- Completely obsolete and heavily fragmented, largely replaced by PDF and lightweight web-based DXF viewers
- Destructive 'snapshot' format irrevocably strips all useful, editable CAD geometry data from the original drawing
- Zero support in web browsers or standard image processing libraries
When to choose which format
JNG
Use JNG when…
- Embedded frames in MNG animations
- Historical web graphics requiring lossy compression with transparency
SLD
Use SLD when…
- Legacy AutoCAD Slideshows
- AutoCAD Custom Icon Menus
- Historical CAD Archival