Thread: compression

isnt the entropy the maximum compression data can be compressed to?

No, to quote http://www.debugmode.com/imagecmp/entrcode.htm,

By entropy, we mean the amount of information present in the data, and an entropy coder encodes the given set of symbols with the minimum number of bits required to represent them.

There are certainly other ways to compress then entropy coding.

also, do you know where i can find any examples of arithmetic coding

http://www.data-compression.info/Algorithms/AC/
At the bottom there are some implemntations. You might have to use a range coder because it's faster, and losses little compression. That would be up to what meets your needs for your program.

i found this example for arithmetic coding

http://pesona.mmu.edu.my/~msng/Arithmetic_Coding.html

i downloaded the source, compiled it, it compresses over 50% which is quite amazing, however it keeps crashing.. not sure why, but it seems perfect for what i was looking for

and i also found an example of a range coder, works perfectly aswell, loses just a little bit of compression compared to the above algo.. loses about 15 bytes or so..

I figured you meant Burrows Wheeler Transform. There are certain legal issues to be aware of using that particular technique. Also, as you probably well know by now, the amount you compress has more to do with what you are compressing more than what algorithm you are compressing with. Under certain conditions an RLE compressor may seem like the best thing ever invented.

There are certain legal issues to be aware of using that particular technique

Are you sure?
From what I've read the two patented algorithms you have to be careful with are LZW and ARI. My understanding was that BWT is in the public domain, and so is the range coder.