What is an Extension segment and how can it be used?
An Extension segment allows the encoder to add any type of additional information to a JBIG2 file. Two extension types are defined in the standard – ASCII and UNICODE. The ASCII Extension type consists of one or more ASCII strings separated by the NULL character. UNICODE is similar to ASCII but uses two bytes to encode each character. Extension segments may contain information about the file, author, application, addition coding techniques, etc. They provide a flexible way to add additional application information to a JBIG2 file. One use would be to add the TIFF author information to the JBIG2 output file. SOC Robotics has defined two additional extension types called BINARY and COLOR. BINARY is similar to ASCII except that binary data of any length can be added to the JBIG2 file. The source application interprets the binary data accordingly. Type COLOR indicates that the JBIG2 file contains a grey scale or color image encoded using JBIG2.
