Image MIME Reference
BMP
Windows Bitmap (Legacy Windows MIME Alias)
image/x-windows-bmp
VS
SealedMedia SoftSeal JPEG
image/vnd.sealedmedia.softseal.jpg
SoftSeal-JPEG
A complete technical comparison of Windows Bitmap (Legacy Windows MIME Alias) and SealedMedia SoftSeal JPEG — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
BMP wins on browser support
Feature Support
| Feature | BMP | SoftSeal-JPEG |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | Yes | ✕ No |
Windows Bitmap (Legacy Windows MIME Alias)
image/x-windows-bmp
Extension
.bmp.dib
Container
DIB (Device-Independent Bitmap)
Compression
Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneRLE4RLE8
Color Depth
1-bit (Monochrome), 4-bit (16 colors), 8-bit (256 colors), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha)
Developed by
Microsoft Corporation
Released
1985
Magic Bytes
42 4D
SealedMedia SoftSeal JPEG
image/vnd.sealedmedia.softseal.jpg
Extension
.sjpg.sealed-jpg.sealed-jpeg
Container
SealedMedia SoftSeal Wrapper
Compression
Encrypted Payload (DCT)
Algorithm
AES EncryptionDiscrete Cosine Transform (Internal JPEG payload)
Color Depth
Encrypted Payload (Historically 24-bit RGB)
Developed by
SealedMedia (Acquired by Oracle Corporation)
Released
Late 1990s
Magic Bytes
Unknown (Proprietary SealedMedia Container)
Browser Support Comparison
| Browser | BMP | SoftSeal-JPEG |
|---|---|---|
Chrome
|
✓ 1
|
✕ |
Firefox
|
✓ 1
|
✕ |
Safari
|
✓ 1
|
✕ |
Edge
|
✓ 12
|
✕ |
IE (Legacy)
|
✓
|
✕ |
BMP
BMP Strengths
- Universally supported by all major operating systems and modern web browsers
- Maintains perfect, lossless fidelity because pixel data is stored without lossy compression artifacts
Limitations
- Massive file size overhead due to a lack of modern compression algorithms
- Legacy MIME strings like 'image/x-windows-bmp' can trigger validation warnings in strict security or API environments if unhandled
SoftSeal-JPEG
SoftSeal-JPEG Strengths
- Offered persistent document security; if a sensitive photo was emailed outside the company, it remained encrypted and unviewable without server authentication
- Administrators possessed the ability to remotely revoke viewing rights to a specific image globally at any time
Limitations
- Completely proprietary and relies on a central authentication server; if the server goes offline or the product is deprecated, the image is permanently inaccessible
- Zero support in modern operating systems, web browsers, or standard image editing suites without heavy enterprise client installations
- Oracle effectively discontinued the IRM product line, stranding many legacy sealed documents
When to choose which format
BMP
Use BMP when…
- Legacy Windows Desktop Registry Associations
- Older Enterprise Intranet Applications
- Windows Graphics Archival
SoftSeal-JPEG
Use SoftSeal-JPEG when…
- Enterprise Information Rights Management (IRM)
- Secure Distribution of Sensitive Photography
- Revocable Corporate Document Access