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Image MIME Reference
Radiance

Radiance HDR

image/vnd.radiance
VS

Truevision TGA (Legacy MIME Alias)

image/x-tga
TGA

A complete technical comparison of Radiance HDR 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 Radiance TGA
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
Radiance HDR
image/vnd.radiance
Extension
.hdr.pic.rgbe.xyze
Container Radiance Information Header
Compression Run-Length Encoding (RLE) / Uncompressed
Algorithm
Adaptive Run-Length Encoding (RLE)
Color Depth 32-bit (8-bit per channel RGB + 8-bit shared Exponent)
Developed by Greg Ward (Lawrence Berkeley National Laboratory)
Released 1989
Magic Bytes
23 3F 52 41 44 49 41 4E 43 45
Full Radiance 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 Radiance TGA
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Radiance

Radiance Strengths

  • Universally supported by almost every 3D modeling software, renderer, and game engine in existence
  • RGBE encoding offers a brilliant balance between High Dynamic Range capability and small file size (compared to 32-bit float OpenEXR)
  • Simple, easy-to-parse ASCII header followed by straightforward RLE binary data
Limitations
  • Does not support alpha transparency (no way to store an isolated light source with a transparent background)
  • The shared exponent architecture can occasionally introduce banding or color artifacts in extreme edge cases compared to true 16-bit/32-bit floating-point formats like OpenEXR
  • Zero native browser support for 2D viewing
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

Radiance
Use Radiance when…
  • Image-Based Lighting (IBL)
  • 3D Environment Maps (HDRI Skydomes)
  • Lighting Simulation
  • VFX and CGI Rendering
TGA
Use TGA when…
  • Video Game 3D Textures and Materials
  • 3D Rendering and Animation Sequences
  • Legacy Video Production Workflows

More comparisons

Radiance vs ACES → TGA vs ACES → Radiance vs APNG → TGA vs APNG → Radiance vs AVCI → TGA vs AVCI → Radiance vs AVCS → TGA vs AVCS → Radiance vs AVIF → TGA vs AVIF → All comparisons →
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