J2C (.j2c)
.j2c file signature | image/x-jp2-codestream
JPEG 2000 codestream (J2C) is the raw image data format defined by the JPEG 2000 standard, developed by the Joint Photographic Experts Group and maintained through ISO/IEC and ITU-T specifications. It is used for high-quality image storage, digital archiving, medical imaging, and broadcast workflows, especially where lossless or progressive decoding is needed. The format is generally safe; however, as with other image files, malformed codestreams can expose parser bugs in unsupported or outdated software.
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
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) == signatureHow to validate .j2c files in 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
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
/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 identified by the magic bytes FF 4F FF 51 at byte offset 0. JPEG 2000 codestream (J2C) is the raw image data format defined by the JPEG 2000 standard, developed by the Joint Photographic Experts Group and maintained through ISO/IEC and ITU-T specifications. It is used for high-quality image storage, digital archiving, medical imaging, and broadcast workflows, especially where lossless or progressive decoding is needed. The format is generally safe; however, as with other image files, malformed codestreams can expose parser bugs in unsupported or outdated software.
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.