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Image MIME Reference
HTJ2K-(JPH)

High-Throughput JPEG 2000 Image

image/jph
VS

Silicon Graphics Image

image/x-rgb
SGI-RGB

A complete technical comparison of High-Throughput JPEG 2000 Image and Silicon Graphics Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature HTJ2K-(JPH) SGI-RGB
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
High-Throughput JPEG 2000 Image
image/jph
Extension
.jph
Container JPH (ISO/IEC 15444-15)
Compression Lossy / Lossless
Algorithm
High-Throughput JPEG 2000 (HTJ2K)
Color Depth 8-bit, 16-bit, 32-bit, 38-bit
Developed by Joint Photographic Experts Group (JPEG)
Released 2019
Magic Bytes
00 00 00 0C 6A 50 20 20 0D 0A 87 0A ... 66 74 79 70 6A 70 68 20
Full HTJ2K-(JPH) reference →
Silicon Graphics Image
image/x-rgb
Extension
.rgb.sgi.rgba.bw.int.inta
Container SGI Image Header (512 bytes)
Compression Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneScanline RLE
Color Depth 8-bit (Per Channel), 16-bit (Per Channel)
Developed by Silicon Graphics, Inc. (Paul Haeberli)
Released 1988
Magic Bytes
01 DA
Full SGI-RGB reference →

Browser Support Comparison

Browser HTJ2K-(JPH) SGI-RGB
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
HTJ2K-(JPH)

HTJ2K-(JPH) Strengths

  • Delivers orders of magnitude faster encoding and decoding than standard JPEG 2000 by utilizing a new, parallelizable block coder
  • Supports mathematically lossless and lossy compression within the same codestream architecture
  • Allows for resolution scalability, progressive decoding, and region-of-interest extraction without needing to decode the entire image
Limitations
  • Zero native web browser support, requiring specialized libraries, API conversions, or WebAssembly (like OpenJPH.js) for web deployment
  • Lack of broad consumer awareness, keeping it confined to professional, medical, and scientific workflows
  • Requires more advanced software ecosystems to decode than ubiquitous formats like JPEG or WebP
SGI-RGB

SGI-RGB Strengths

  • Supports 16-bit precision per channel and an embedded alpha channel, making it ideal for the demanding compositing workflows of 1990s cinema VFX
  • The scanline-based RLE compression was exceptionally fast to decode on classic MIPS-based SGI workstations
  • Features a straightforward 512-byte header, making it relatively easy to parse and write custom decoders in C or Python
Limitations
  • Completely obsolete and unsupported in modern web environments
  • Replaced entirely by TIFF, OpenEXR, and PNG in modern visual effects and 3D rendering pipelines
  • Lacks support for modern color management via ICC profiles or advanced EXIF metadata

When to choose which format

HTJ2K-(JPH)
Use HTJ2K-(JPH) when…
  • Medical Imaging (DICOM)
  • Geospatial Data
  • Digital Cinema
  • Professional Archiving
SGI-RGB
Use SGI-RGB when…
  • Legacy 3D Animation and VFX Textures
  • Silicon Graphics IRIX Workstation Archival
  • 1990s Medical Imaging

More comparisons

HTJ2K-(JPH) vs ACES → SGI-RGB vs ACES → HTJ2K-(JPH) vs APNG → SGI-RGB vs APNG → HTJ2K-(JPH) vs AVCI → SGI-RGB vs AVCI → HTJ2K-(JPH) vs AVCS → SGI-RGB vs AVCS → HTJ2K-(JPH) vs AVIF → SGI-RGB vs AVIF → All comparisons →
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