JBIG2 Filter
From GNUpdf
There are software patents by IBM, Mitsubishi and AT&T covering an aspect of JBIG2 encoding (arithmetic encoding). The encoder released by the JBIG group uses arithmetic encoding, so we are unable to use that encoder.
Some people suggest that range checking encoding could be used in order to avoid that patent. The output of the range encoding would need to be equal as with arithmetic encoding.
