XnView Software

Main problem with using arithmetic coding (especially in a freeware prog) is that there are a lot of patents on it (similar situation to he gif format, before the gif patents ran out).
Yeah I know about the patent, but I just wanna build & keep it for my self something like testing purposes only ...

Addition to XnTriq
Xat Image Optimizer able to read/guess(?) JPEG quality

I have jpeglib with arithmetic function (taken from jpegcrop source code)
Does anybody know how to build plugin with this library?