Definition(en): JPEG 2000 codestream (also known as J2K, J2C, or JPEG 2000 Part 1, Core Coding System) is the wavelet based compressed image format defined in Part 1 of the JPEG 2000 standard. Both lossy and lossless compression as supported. A JPEG 2000 codestream uses a variant of the JPEG format, with a nearly identical system of markers and segments.