[ros-dev] Re: [ros-svn] [mbosma] 20952: Delete libjpeg because sedwards and greatlord thought we should wait with jpeg support until the patent expired. If someone got a different opinion please take the issue to ros-dev.

mf mf at mufunyo.net
Fri Jan 20 20:59:40 CET 2006

art yerkes wrote:
> There's a lot of FUD going on here.
I agree wholeheartedly.
> For one thing, our SEH method is not patented.
For another thing, the patent appears to be this:

The JPEG spec defines two different "back end" modules for the final 
output of compressed data: either Huffman coding or arithmetic coding is 
allowed. The choice has no impact on image quality, but arithmetic 
coding usually produces a smaller compressed file.  On typical images, 
arithmetic coding produces a file 5 to 10 percent smaller than Huffman 
coding.  (All the file-size numbers previously cited are for Huffman 

Unfortunately, the particular variant of arithmetic coding specified by 
the JPEG standard is subject to patents owned by IBM, AT&T, and 
Mitsubishi. Thus *you cannot legally use JPEG arithmetic coding* unless 
you obtain licenses from these companies.  (Patent law's "experimental 
use" exception allows people to test a patented method in the context of 
scientific research, but any commercial or routine personal use is 

I recommend that people not use JPEG arithmetic coding; the space 
savings isn't great enough to justify the potential legal hassles.  In 
particular, arithmetic coding *should not* be used for any images to be 
exchanged on the Internet.  Even if you don't care about US patent law, 
other folks do.

I believe that something like that is easily commented out, and does not 
require a removal of the entire lib. *sings the FUD song*


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