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JPEG-XR-(HEIF)

JPEG XR Image (HEIF Container)

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

The image/jxra MIME type (often styled as image/jxrA) represents a JPEG XR (Extended Range) single image or image collection encapsulated within the High Efficiency Image File Format (HEIF) container. Standardized in Annex F of ITU-T T.832, it combines the powerful compression and HDR capabilities of JPEG XR with the flexible metadata and box structure of the ISOBMFF-based HEIF container.

Photography & Archival Transparency Progressive ✦ HDR Production Ready

Technical Specifications

MIME Type
image/jxra
Extensions
.jxra
Container
HEIF / ISOBMFF (ISO/IEC 23008-12 / Annex F of ITU-T T.832)
Compression
Lossy & Lossless
Algorithms
JPEG XR (Lapped Biorthogonal Transform)
Color Depth
8-bit, 16-bit, 32-bit (Float)
Metadata
EXIF XMP ICC
Capabilities
Transparency
Animation
Progressive Loading
Alpha Channel
HDR Support
Official Specification
Aliases: image/jxrA

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)
XX XX XX XX 66 74 79 70 6A 78 72 41
ASCII: ....ftypjxrA
HTTP Headers
Content-Type: image/jxra
Content-Type: image/jxrA
HTML Accept Attribute
accept="image/jxra, image/jxrA, .jxra"

Browser Support Matrix

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

Advantages & Limitations

Advantages
  • Combines the deep color (32-bit float) and mathematically lossless compression of JPEG XR with the robust metadata architecture of HEIF
  • Allows grouping multiple images, exposure brackets, or focal stacks into a single file collection
Limitations
  • Practically non-existent software and operating system support compared to standard HEIC or legacy JPEG XR (.jxr)
  • Zero web browser support, rendering it entirely unsuitable for public web deployment
  • Eclipsed by modern standards like AVIF and JPEG XL which offer superior compression with much broader industry backing

Developer Code Snippets

import magic
print(magic.from_file('photo.jxra', mime=True)) # Will likely default to generic 'image/heif' or 'application/octet-stream' without manual configuration
const FileType = require('file-type');
const type = await FileType.fromFile('photo.jxra');
console.log(type?.mime); // Standard parsers may fail to recognize the specific 'jxrA' brand
import "net/http"
// The standard net/http library cannot detect specific HEIF sub-brands.
// Custom ISOBMFF box parsing is required to read the 'jxrA' string.
$mime = mime_content_type('photo.jxra');
echo $mime; // Standard server environments will often resolve this to application/octet-stream

File Detection Steps

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

  1. 1 Check for the standard ISOBMFF 'ftyp' box starting at byte offset 4
  2. 2 Verify the major brand string starting at byte offset 8 is exactly 'jxrA' (6A 78 72 41)

Software Support

ImageMagick ImageMagick

Conversion Tools

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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/jpeg-xr-(heif).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 image/jxr and image/jxra?

image/jxr refers to the original JPEG XR image format (previously Microsoft HD Photo), which utilizes a TIFF-like file structure. image/jxra represents JPEG XR compressed data housed within a modern HEIF (High Efficiency Image File Format) container.

What is the magic byte for an image/jxra file?

Because it relies on the HEIF/ISOBMFF container format, an image/jxra file begins with a 4-byte box size, followed by the 'ftyp' box identifier, and the major brand 'jxrA'. In hex, this signature is XX XX XX XX 66 74 79 70 6A 78 72 41.

Is image/jxra widely supported in web browsers or software?

No. While HEIF containers are popular for storing HEVC-encoded images (HEIC), embedding JPEG XR data inside HEIF is extremely rare. There is zero native web browser support, and it is largely confined to experimental workflows or highly specialized archival standards.

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