Image MIME Reference
HTJ2K-(JPH)
High-Throughput JPEG 2000 Image
image/jph
VS
Portable Network Graphics (Legacy MIME)
image/x-png
PNG
A complete technical comparison of High-Throughput JPEG 2000 Image and Portable Network Graphics (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
PNG wins on browser support
Feature Support
| Feature | HTJ2K-(JPH) | PNG |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | Yes |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | Yes |
| ICC Color Profile | Yes | Yes |
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
Portable Network Graphics (Legacy MIME)
image/x-png
Extension
.png
Container
PNG Chunk Structure (IHDR, IDAT, IEND)
Compression
Deflate (Lossless)
Algorithm
Deflate (LZ77)
Color Depth
1-bit to 16-bit (Grayscale), 8-bit (Indexed Palette), 24-bit (True Color), 32-bit (True Color with Alpha), 48-bit (High Color), 64-bit (High Color with Alpha)
Developed by
PNG Development Group
Released
1996
Magic Bytes
89 50 4E 47 0D 0A 1A 0A
Browser Support Comparison
| Browser | HTJ2K-(JPH) | PNG |
|---|---|---|
Chrome
|
✕ |
✓ 1
|
Firefox
|
✕ |
✓ 1
|
Safari
|
✕ |
✓ 1
|
Edge
|
✕ |
✓ 12
|
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
PNG
PNG Strengths
- The underlying format provides flawless, lossless compression and perfect 8-bit alpha channel transparency
- Universally supported by every modern operating system, image editor, and web browser
Limitations
- The 'image/x-png' string is an obsolete vendor quirk that forces backend developers to write redundant normalization logic in file upload scripts
- If left unnormalized, strict MIME validators or content security policies on modern systems may incorrectly reject valid PNG files
When to choose which format
HTJ2K-(JPH)
Use HTJ2K-(JPH) when…
- Medical Imaging (DICOM)
- Geospatial Data
- Digital Cinema
- Professional Archiving
PNG
Use PNG when…
- Legacy Internet Explorer File Uploads
- Older ASP/PHP Web Applications
- Lossless Web Graphics