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Image MIME Reference
Alias-PIX

Alias PIX Image

image/x-alias-pix
VS

Truevision TGA (Legacy MIME Alias)

image/x-tga
TGA

A complete technical comparison of Alias PIX Image and Truevision TGA (Legacy MIME Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Alias-PIX TGA
Transparency (Alpha) ✕ No Yes
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 →
Truevision TGA (Legacy MIME Alias)
image/x-tga
Extension
.tga.icb.vda.vst
Container Truevision TGA Footer/Header
Compression Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneRLE
Color Depth 8-bit (Grayscale or Indexed), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha Channel)
Developed by Truevision Inc.
Released 1984
Magic Bytes
54 52 55 45 56 49 53 49 4F 4E 2D 58 46 49 4C 45 2E 00 (At the end of the file)
Full TGA reference →

Browser Support Comparison

Browser Alias-PIX TGA
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  • Completely obsolete, having been replaced by more robust formats like TIFF, TGA, and EXR in modern 3D pipelines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
TGA

TGA Strengths

  • Incredibly simple byte layout allows developers to write custom loaders and exporters in a few dozen lines of code, bypassing the need for heavy external libraries
  • Native support for 8-bit alpha channels ensures flawless transparency masking for real-time 3D rendering
  • Fast, predictable RLE decoding requires almost no CPU overhead compared to DEFLATE (PNG) or DCT (JPEG)
Limitations
  • RLE compression is relatively weak by modern standards, resulting in large file sizes
  • Lacks a standard magic byte header at the beginning of the file, making file-sniffing unreliable for older v1.0 files
  • Zero support in web browsers; must be converted to PNG or WebP for web delivery

When to choose which format

Alias-PIX
Use Alias-PIX when…
  • Legacy Alias PowerAnimator Textures
  • 1990s SGI Workstation Render Outputs
  • Historical 3D Graphics Archival
TGA
Use TGA when…
  • Video Game 3D Textures and Materials
  • 3D Rendering and Animation Sequences
  • Legacy Video Production Workflows

More comparisons

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