JPEG 2000 codestream
From Just Solve the File Format Problem
Overview
JPEG2000 codestream (also known as J2K, J2C, or JPEG 2000 Part 1, Core Coding System) is the wavelet-based compressed image format defined by Part 1 of the JPEG 2000 standard. It may appear in a file by itself, or embedded in JP2 or another file format.
It uses a variant of JPEG format, with the same system of markers and segments. Note that the container formats used by JP2 and other JPEG2000 file formats are completely different.
See JP2 and JPEG2000 for more information.
Identification
Files start with bytes ff 4f ff.
