J2C

JPEG 2000 Codestream

image/j2c Released 2000 · by Joint Photographic Experts Group (JPEG)

The image/j2c MIME type represents a raw JPEG 2000 Codestream. Unlike the standard image/jp2 format, which encapsulates the image in a structured container alongside color profiles and metadata, an image/j2c file contains only the raw, wavelet-compressed pixel data. It is heavily used in professional broadcasting, Digital Cinema Packages (DCP), and medical imaging architectures where metadata and timing are handled externally by multiplexing formats (like MXF).

Photography & Broadcast Transparency Progressive ✦ HDR Production Ready

Technical Specifications

MIME Type

image/j2c

Extensions

.j2c.j2k.jpc

Container

None (Raw Bitstream)

Compression

JPEG 2000 (Discrete Wavelet Transform) & Lossless & Lossy

Algorithms

Discrete Wavelet Transform (DWT)

Color Depth

8-bit, 10-bit, 12-bit, 16-bit (Per Channel)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/x-jp2-codestream

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

FF 4F FF 51

ASCII: ÿOÿQ

HTTP Headers

Content-Type: image/j2c

HTML Accept Attribute

accept="image/j2c, image/x-jp2-codestream, .j2c, .j2k, .jpc"

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

Provides state-of-the-art wavelet compression for high-end professional workflows (Digital Cinema)
Allows for highly efficient progressive decoding (by resolution or quality layer) natively within the stream
Supports lossless mathematical compression and high bit-depths (up to 16-bit per channel) natively

Limitations

Lacks a standard container to store color space info or metadata, requiring external systems (like MXF or DICOM) to map colors correctly
Extremely computationally expensive to encode and decode compared to standard DCT-based JPEG
Zero web browser support

Developer Code Snippets

import magic
# Libmagic accurately detects the SOC marker for JPEG 2000 codestreams
print(magic.from_file('stream.j2c', mime=True)) # Outputs 'image/j2c'

const FileType = require('file-type');
const type = await FileType.fromFile('stream.j2c');
console.log(type.mime); // Outputs 'image/j2c'

import "net/http"
// Custom byte sniff required for raw J2C since net/http might miss it
// isJ2C := bytes.HasPrefix(buf, []byte{0xFF, 0x4F, 0xFF, 0x51})

$mime = mime_content_type('stream.j2c');
echo $mime; // Standard setups generally resolve this to 'image/j2c'

File Detection Steps

How to programmatically detect a image/j2c file by reading its raw bytes:

1 Check the first 2 bytes for the Start of Codestream (SOC) marker: FF 4F
2 Verify the following 2 bytes for the SIZ marker: FF 51
3 Unlike JP2 files which start with a standard box structure ('jP ' / 00 00 00 0C 6A 50 20 20), J2C skips the container entirely and starts directly with the SOC marker.

Software Support

F

FFmpeg

ImageMagick

O

OpenJPEG

K

Kakadu Software

Conversion Tools

Share & Embed

Markdown Badge

[![J2C Format](https://freewebptojpg.com/mime/image/j2c/badge.svg)](https://freewebptojpg.com/mime/image/j2c)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/j2c/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="J2C 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/j2c.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 J2C?

JP2 (image/jp2) is a container format that includes a JPEG 2000 codestream alongside essential metadata like ICC color profiles, resolution, and EXIF data. J2C (image/j2c) is purely the raw, compressed image data stream (the codestream) stripped of this outer container.

What are the magic bytes for a J2C codestream?

A raw JPEG 2000 codestream always begins with the Start of Codestream (SOC) marker, which is the 2-byte hex sequence FF 4F. This is immediately followed by the Image and Tile Size (SIZ) marker, FF 51. So, the first 4 bytes are typically FF 4F FF 51.

Can I display image/j2c files in a web browser?

No. While Apple's Safari browser has native support for the JP2 container format, no modern web browsers support decoding raw J2C codestreams. For web delivery, they must be converted to standard formats like WebP, AVIF, or JPEG.