Image MIME Reference
KTX
Khronos Texture
image/ktx
VS
SealedMedia SoftSeal JPEG
image/vnd.sealedmedia.softseal.jpg
SoftSeal-JPEG
A complete technical comparison of Khronos Texture and SealedMedia SoftSeal JPEG — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | KTX | SoftSeal-JPEG |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Khronos Texture
image/ktx
Extension
.ktx
Container
KTX (Khronos Texture 1.1)
Compression
Uncompressed / GPU Compressed (ASTC, ETC, BCn, PVRTC)
Algorithm
ASTCETC1 / ETC2BCn (DXT)PVRTCBasis Universal (in KTX2)
Color Depth
8-bit, 16-bit, 32-bit (Integer/Float)
Developed by
Khronos Group
Released
2010
Magic Bytes
AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A
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 | KTX | SoftSeal-JPEG |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
KTX
KTX Strengths
- Enables direct-to-GPU texture uploading, drastically reducing load times and CPU overhead in 3D applications
- Supports complex texture types natively (mipmaps, cubemaps, 3D volumes, texture arrays)
- Standardized across major Khronos APIs (OpenGL, Vulkan, WebGL) unlike vendor-specific formats like DDS
Limitations
- Requires custom JavaScript loaders to parse and display on the web
- Zero native support in consumer image viewers or 2D photo editing software
- Format fragmentation: a KTX file containing an ASTC payload will fail to render on hardware that only supports BCn compression (KTX2 and Basis Universal solve this)
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
KTX
Use KTX when…
- Real-time 3D Graphics
- WebGL / WebGPU Applications
- Mobile Games
- Virtual/Augmented Reality (VR/AR)
SoftSeal-JPEG
Use SoftSeal-JPEG when…
- Enterprise Information Rights Management (IRM)
- Secure Distribution of Sensitive Photography
- Revocable Corporate Document Access