Image MIME Reference
SLD
AutoCAD Slide
image/vnd.sld
VS
SealedMedia SoftSeal GIF
image/vnd.sealedmedia.softseal.gif
SoftSeal-GIF
A complete technical comparison of AutoCAD Slide and SealedMedia SoftSeal GIF — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | SLD | 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 |
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
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 | SLD | SoftSeal-GIF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
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
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
SLD
Use SLD when…
- Legacy AutoCAD Slideshows
- AutoCAD Custom Icon Menus
- Historical CAD Archival
SoftSeal-GIF
Use SoftSeal-GIF when…
- Enterprise Information Rights Management (IRM)
- Secure Distribution of Corporate Assets
- Revocable Medical, Legal, or Financial Imaging