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Image MIME Reference
AVCS

AVC Image Sequence (HEIF Container)

image/avcs
VS

Radiance HDR

image/vnd.radiance
Radiance

A complete technical comparison of AVC Image Sequence (HEIF Container) and Radiance HDR — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature AVCS Radiance
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
AVC Image Sequence (HEIF Container)
image/avcs
Extension
.avcs.heifs
Container HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression Lossy / Lossless
Algorithm
AVC (Advanced Video Coding / H.264)
Color Depth 8-bit, 10-bit, 12-bit
Developed by Moving Picture Experts Group (MPEG) / ISO/IEC JTC 1
Released 2015
Magic Bytes
XX XX XX XX 66 74 79 70 61 76 63 73
Full AVCS reference →
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 →

Browser Support Comparison

Browser AVCS Radiance
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
AVCS

AVCS Strengths

  • Efficiently stores bursts of images or animations utilizing inter-frame compression
  • Leverages the highly compatible and widely hardware-accelerated AVC (H.264) codec
  • Robust HEIF container supports extensive metadata, alpha channels, and depth maps
Limitations
  • Zero native support in web browsers
  • Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)
  • Complicated container structure requires specialized parsing libraries
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

When to choose which format

AVCS
Use AVCS when…
  • Burst Photography
  • Short Animations
  • Camera Capture
  • Archival Storage
Radiance
Use Radiance when…
  • Image-Based Lighting (IBL)
  • 3D Environment Maps (HDRI Skydomes)
  • Lighting Simulation
  • VFX and CGI Rendering

More comparisons

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