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J2C (.j2c)

.j2c file signature | image/x-jp2-codestream

JPEG 2000format[18]

Safe

Magic Bytes

Offset 0
FF 4F FF 51

Sources: Apache Tika

All Known Signatures

2 signature variants are documented for .j2c files across multiple sources.

Hex Signature Offset Sources
FF 4F FF 51 0 Apache Tika
00 00 00 0C 6A 50 20 20 0D 0A 87 0A 0 Wikipedia

Extension

.j2c

MIME Type

image/x-jp2-codestream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .j2c files in Python

Python
def is_j2c(file_path: str) -> bool:
    """Check if file is a valid J2C by magic bytes."""
    signature = bytes([0xFF, 0x4F, 0xFF, 0x51])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .j2c files in Node.js

Node.js
function isJ2C(buffer: Buffer): boolean {
  const signature = Buffer.from([0xFF, 0x4F, 0xFF, 0x51]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .j2c files in Go

Go
func IsJ2C(data []byte) bool {
    signature := []byte{0xFF, 0x4F, 0xFF, 0x51}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

GET /api/v1/j2c
curl https://filesignature.org/api/v1/j2c

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .j2c file?

A .j2c file is a J2C file. JPEG 2000format[18]

What are the magic bytes for .j2c files?

The magic bytes for J2C files are FF 4F FF 51 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .j2c file?

To validate a .j2c file, read the first bytes of the file and compare them against the known magic bytes (FF 4F FF 51) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .j2c files?

The primary MIME type for .j2c files is image/x-jp2-codestream.

Is it safe to open .j2c files?

J2C (.j2c) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.