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Image MIME Reference
Alias-PIX

Alias PIX Image

image/x-alias-pix
VS

SealedMedia Portable Network Graphics

image/vnd.sealed.png
Sealed-PNG

A complete technical comparison of Alias PIX Image and SealedMedia Portable Network Graphics — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Alias-PIX Sealed-PNG
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
Alias PIX Image
image/x-alias-pix
Extension
.pix.als.alias.img
Container Alias PIX Header
Compression Run-Length Encoding (RLE)
Algorithm
RLE
Color Depth 24-bit (RGB), 8-bit (Matte/Grayscale variant)
Developed by Alias Research (Later Alias|Wavefront / Autodesk)
Released Early 1990s
Magic Bytes
No explicit magic bytes (Relies on 10-byte integer header)
Full Alias-PIX reference →
SealedMedia Portable Network Graphics
image/vnd.sealed.png
Extension
.spng.sealed-png
Container SealedMedia / Oracle IRM Wrapper
Compression Encrypted Payload (Deflate)
Algorithm
AES EncryptionDeflate (Internal PNG payload)
Color Depth Encrypted Payload
Developed by SealedMedia (Acquired by Oracle Corporation)
Released Late 1990s / Early 2000s
Magic Bytes
Unknown (Proprietary SealedMedia Container)
Full Sealed-PNG reference →

Browser Support Comparison

Browser Alias-PIX Sealed-PNG
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Alias-PIX

Alias-PIX Strengths

  • The highly simplified structure made it incredibly fast to encode and decode on early 1990s SGI hardware
  • Lossless Run-Length Encoding (RLE) saved disk space without degrading the quality of final 3D renders
Limitations
  • Completely obsolete, having been replaced by more robust formats like TIFF, TGA, and EXR in modern 3D pipelines
  • The lack of a distinct magic byte signature makes reliable automated file detection almost impossible
  • Does not support integrated alpha channels, instead requiring cumbersome, separate 'Matte' files to denote transparency
Sealed-PNG

Sealed-PNG Strengths

  • Provided absolute control over intellectual property, allowing enterprise administrators to instantly revoke viewing rights of a local file globally
  • Detailed audit trails tracked exactly who opened the image, when, and from what IP address
Limitations
  • Completely proprietary and relies on a central authentication server; if the server goes offline, the image is permanently inaccessible
  • No support in modern operating systems, web browsers, or standard image editing software without installing heavy enterprise DRM clients
  • Oracle effectively deprecated the IRM product line, leaving legacy sealed documents difficult to recover

When to choose which format

Alias-PIX
Use Alias-PIX when…
  • Legacy Alias PowerAnimator Textures
  • 1990s SGI Workstation Render Outputs
  • Historical 3D Graphics Archival
Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging

More comparisons

Alias-PIX vs ACES → Sealed-PNG vs ACES → Alias-PIX vs APNG → Sealed-PNG vs APNG → Alias-PIX vs AVCI → Sealed-PNG vs AVCI → Alias-PIX vs AVCS → Sealed-PNG vs AVCS → Alias-PIX vs AVIF → Sealed-PNG vs AVIF → All comparisons →
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