HTJ2K-(JPH)

High-Throughput JPEG 2000 Image

image/jph Released 2019 · by Joint Photographic Experts Group (JPEG)

The image/jph MIME type represents the JPH file format, which encapsulates High-Throughput JPEG 2000 (HTJ2K) codestreams. Standardized as ISO/IEC 15444-15 (JPEG 2000 Part 15), HTJ2K replaces the original JPEG 2000 block coder with an extremely fast, parallelizable block coder. This allows for an order of magnitude faster encoding and decoding while preserving advanced features like mathematically lossless compression and resolution scalability.

Professional & Archival Transparency Progressive ✦ HDR Production Ready

Technical Specifications

MIME Type

image/jph

Extensions

.jph

Container

JPH (ISO/IEC 15444-15)

Compression

Lossy & Lossless

Algorithms

High-Throughput JPEG 2000 (HTJ2K)

Color Depth

8-bit, 16-bit, 32-bit, 38-bit

Metadata

EXIF XMP ICC

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/x-jph

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

00 00 00 0C 6A 50 20 20 0D 0A 87 0A ... 66 74 79 70 6A 70 68 20

ASCII: ....jP ........ftypjph

HTTP Headers

Content-Type: image/jph

HTML Accept Attribute

accept="image/jph, .jph"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

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

Developer Code Snippets

import magic
print(magic.from_file('image.jph', mime=True)) # May default to generic 'image/jp2' or 'application/octet-stream' without an updated magic database

const FileType = require('file-type');
const type = await FileType.fromFile('image.jph');
console.log(type?.mime); // Standard parsers may miss the specific 'jph ' brand check

import "net/http"
// Custom ISOBMFF box parsing is required to read the 'jph ' brand inside the ftyp box.

$mime = mime_content_type('image.jph');
echo $mime; // Standard implementations often map this to application/octet-stream

File Detection Steps

How to programmatically detect a image/jph file by reading its raw bytes:

1 Check the first 12 bytes for the JPEG 2000 signature box (00 00 00 0C 6A 50 20 20 0D 0A 87 0A)
2 Check the immediately following File Type (ftyp) box to ensure the major brand string is 'jph ' (6A 70 68 20) to confirm it is an HTJ2K file rather than a standard JP2 file

Software Support

O

OpenJPH

K

Kakadu Software

G

Grok

ImageMagick

Conversion Tools

Share & Embed

Markdown Badge

[![HTJ2K-(JPH) Format](https://freewebptojpg.com/mime/image/htj2k-(jph)/badge.svg)](https://freewebptojpg.com/mime/image/htj2k-(jph))

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/htj2k-(jph)/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="HTJ2K-(JPH) Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/htj2k-(jph).json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is the difference between JP2 and JPH?

Both are container formats in the JPEG 2000 family based on the box-structured architecture. While JP2 (image/jp2) uses the original JPEG 2000 block coder (Part 1), JPH specifically encapsulates High-Throughput JPEG 2000 (HTJ2K, Part 15) codestreams designed for significantly faster, parallelized processing.

What is the magic byte for a JPH file?

A JPH file begins with the standard 12-byte JPEG 2000 signature box (00 00 00 0C 6A 50 20 20 0D 0A 87 0A). This is immediately followed by the 'ftyp' (File Type) box, which explicitly contains the major brand 'jph ' (6A 70 68 20 in hex).

Are HTJ2K / JPH images supported in web browsers?

No. Like standard JPEG 2000, there is no native support for High-Throughput JPEG 2000 in modern web browsers. It is primarily used in specialized imaging fields such as medical imaging (DICOM), geospatial analysis, digital cinema, and professional archiving.