HSJ2

JPEG 2000 Image Sequence (Obsolete)

image/hsj2 Released 2019 · by ISO/IEC JTC 1 / ITU-T

HSJ2 is an obsolete MIME type originally designed to encapsulate Motion JPEG 2000 (ISO/IEC 15444-3) image sequences within a High Efficiency Image File Format (HEIF) container. It has been officially deprecated by the JPEG committee and superseded by the newer image/hej2k format.

Legacy Transparency Animation Progressive ✦ HDR Production Ready

Technical Specifications

MIME Type

image/hsj2

Extensions

.hsj2

Container

HEIF / ISOBMFF (ISO/IEC 15444-16 Obsolete)

Compression

Lossy & Lossless

Algorithms

Motion JPEG 2000 (ISO/IEC 15444-3)

Color Depth

8-bit, 10-bit, 12-bit, 16-bit

Metadata

EXIF XMP ICC

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/hej2k

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

XX XX XX XX 66 74 79 70 68 73 6A 32

ASCII: ....ftyphsj2

HTTP Headers

Content-Type: image/hsj2

HTML Accept Attribute

accept="image/hsj2, .hsj2"

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

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Completely superseded by image/hej2k, rendering hsj2 files obsolete for any new development or archiving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

Developer Code Snippets

import magic
print(magic.from_file('sequence.hsj2', mime=True)) # May default to generic 'application/octet-stream' or 'image/heif'

const FileType = require('file-type');
const type = await FileType.fromFile('sequence.hsj2');
console.log(type?.mime); // Standard libraries will likely not detect this deprecated format natively

import "net/http"
// Custom ISOBMFF parsing is required to detect historical 'hsj2' container brands.

$mime = mime_content_type('sequence.hsj2');
echo $mime; // application/octet-stream

File Detection Steps

How to programmatically detect a image/hsj2 file by reading its raw bytes:

1 Check for ISOBMFF 'ftyp' box starting at byte offset 4
2 Verify historical 'hsj2' brand string or similar Motion JPEG 2000 signature starting at byte offset 8

Software Support

K

Kakadu Software (Legacy)

Conversion Tools

Share & Embed

Markdown Badge

[![HSJ2 Format](https://freewebptojpg.com/mime/image/hsj2/badge.svg)](https://freewebptojpg.com/mime/image/hsj2)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/hsj2/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="HSJ2 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/hsj2.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 image/hsj2 format?

It is an obsolete MIME type and encapsulation method intended to store Motion JPEG 2000 image sequences inside a HEIF (ISOBMFF) container.

Is HSJ2 still used?

No. The encapsulation of these image sequences and the image/hsj2 media type are deprecated and not recommended for new applications. They have been entirely replaced by the image/hej2k media type for JPEG 2000 image sequences.

Are HSJ2 images supported in web browsers?

No. There is zero native web browser support for this deprecated JPEG 2000 sequence format.