J2C
image/x-jp2-codestream
Magic Bytes
Offset: 0
FF 4F FF 51
The J2C format is the raw codestream specification for the JPEG 2000 image compression standard, developed by the Joint Photographic Experts Group. This file type stores compressed image data without the structural headers and metadata wrapper found in standard JP2 files, serving primarily in medical imaging and geospatial applications. While generally considered safe as a raster image format, users should ensure their viewing software is updated to prevent exploitation of historical buffer overflow vulnerabilities in older processing libraries.
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) == signatureHow 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);
}
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