Free webp to jpg
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Image MIME Reference
HSJ2

JPEG 2000 Image Sequence (Obsolete)

image/hsj2
VS

Scalable Vector Graphics

image/svg+xml
SVG

A complete technical comparison of JPEG 2000 Image Sequence (Obsolete) and Scalable Vector Graphics — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

SVG wins on browser support

Feature Support

Feature HSJ2 SVG
Transparency (Alpha) Yes Yes
Animation Support Yes Yes
Progressive Loading Yes ✕ No
HDR Support Yes Yes
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG 2000 Image Sequence (Obsolete)
image/hsj2
Extension
.hsj2
Container HEIF / ISOBMFF (ISO/IEC 15444-16 Obsolete)
Compression Lossy / Lossless
Algorithm
Motion JPEG 2000 (ISO/IEC 15444-3)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit
Developed by ISO/IEC JTC 1 / ITU-T
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 68 73 6A 32
Full HSJ2 reference →
Scalable Vector Graphics
image/svg+xml
Extension
.svg.svgz
Container XML Document
Compression Uncompressed (Plain Text XML) / Lossless (GZIP via .svgz)
Algorithm
None (for .svg)GZIP (for .svgz)
Color Depth Vector (Independent of bit-depth), CSS Colors (HEX, RGB, HSL, Display-P3)
Developed by World Wide Web Consortium (W3C)
Released 2001
Magic Bytes
3C 73 76 67 (for <svg) / 3C 3F 78 6D 6C (for <?xml)
Full SVG reference →

Browser Support Comparison

Browser HSJ2 SVG
Chrome Chrome
✕
✓ All
Firefox Firefox
✕
✓ All
Safari Safari
✕
✓ All
Edge Edge
✕
✓ All
IE IE (Legacy)
✕
✓
HSJ2

HSJ2 Strengths

  • Historically attempted to combine Motion JPEG 2000 sequences with the flexible metadata capabilities of the HEIF container
  • Supported mathematically lossless compression and scalable wavelet decoding
Limitations
  • Officially deprecated by the standardization body (ISO/IEC JTC 1)
  • Completely superseded by image/hej2k, rendering hsj2 files obsolete for any new development or archiving
  • Zero web browser compatibility and negligible modern software support
SVG

SVG Strengths

  • Provides infinite resolution scalability, looking perfectly crisp on high-DPI (Retina) displays without increasing file size
  • Extremely lightweight compared to raster formats for flat graphics, logos, and UI elements
  • Can be manipulated dynamically via the browser's CSS and JavaScript engines (DOM integration)
Limitations
  • Unsuitable for complex photographic images or photorealistic textures
  • Poses critical security vulnerabilities (XSS and XML External Entity attacks) if user-uploaded SVGs are not heavily sanitized
  • Rendering performance degrades significantly if the SVG contains tens of thousands of complex nodes or deeply nested paths

When to choose which format

HSJ2
Use HSJ2 when…
  • Legacy Archival
  • Deprecated Workflows
SVG
Use SVG when…
  • Web Logos & UI Icons
  • Responsive Web Design Elements
  • Interactive Data Visualizations (D3.js)
  • CSS and SMIL Web Animations

More comparisons

HSJ2 vs ACES → SVG vs ACES → HSJ2 vs APNG → SVG vs APNG → HSJ2 vs AVCI → SVG vs AVCI → HSJ2 vs AVCS → SVG vs AVCS → HSJ2 vs AVIF → SVG vs AVIF → All comparisons →
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