1998.11.13 15:59 "Re: Revison 7.0", by Tom Lane

In general I am a little bit confused from patents.

Some of us doubt that software patents are really legal under US law either... but unless someone with deep pockets decides to press the issue, the defacto situation is that you can patent an algorithm.

Ok JBIG uses some patents. Up to know I have thought, that JPEG uses patents ( arithmetic coding? ) too. Never heard, that someone pay license fees for JPEG.

Yup, same patents. The reason you never see an arithmetic-coded JPEG in the wild is that there are patents on the QM-coder. Fortunately Huffman-coded JPEG is patent free, so that's what everyone uses. JBIG uses the same QM-coder back end as arith-coded JPEG. The JBIG committee's mistake was not to offer a patent-free variant.

I don't know anything about the patent situation for JBIG2.

But on www.jpeg.org/public/jpegnew.htm there is a line which says that IBM will frees it QM patent. What should I think?

1. Too bad they didn't do that eight years ago when they were first asked.
2. IBM is only one company holding relevant patents. This is a nice gesture from them, but unless AT&T and Mitsubishi follow suit, A/C JPEG and JBIG are still not going to be freely usable.

Some time I have read, that a license from one patent owner is enough to use JBIG.

Where did you read that? Possibly the AT&T and Mitsubishi patents don't exist in Germany, but they exist here.

                        regards, tom lane
                        organizer, Independent JPEG Group