I`m I wrong here ? : ISO and BIN files contain extra data, not only files.

Filecompressors compress BIN/ISO as one file. If BIN/ISO contains WAV files, text files, images in BMP - special multimdia/text algorithms will not be used!

I think that: if we only could convert ISO/BIN to: standard files, audio data --> PCM WAV, data needed to recover files to ISO/BIN we could compress cd-images better!

Such program I need is called "converter". I need such converter

Not sure if I understand what you are saying
But;
1 - if you convert an ISO/Bin to another format you no longer have a CD image, which for most programs is not a big deal unless the program really does have to be run from a CD (ie OS, some games, etc)

2 - You are suggesting that if you can extract multimedia files from a CD and compress them with specific multimedia compression algorithms that you would save more space? That is probably true however I think the benifits would be pretty marginal compared to other methods.

Other methods I mean taking a CD image and compressing the image using WinRAR or WinZip - while it probably will take a little while I have seen some very good compression ~40% on some images. So I think that might be a better path than converting.

WinZIP is very bad compressor (low ratio). Always compressing files on CD is better than compressing whole image (higher ratio). I agree that most often files can be just copied and packed, after unpacking installation works.

Difference between dedicated multimedia compressor and e.g. Winzip is HUGE!

Still not sure what you are trying to achieve?
If you have a CD that has just multimedia files - then for sure you can take them off the CD and compress them with a multimedia compressor.
However I thought you were talking about CDs that have all different types of content.

Winzip is not a great compressor, i prefer winrar, but zips are more common so sometimes you have to use them if the person who receives a compressed file may only know about zips

I still believe that if rip a CD image and put it through winrar (which has a multimedia setting I believe but I don't think it would work for a CD image) you will still come out close to trying to dissect the CD image and compress the files based on content.

I think TwoJ would be absolutely right if you just use WinRAR (or whatever you prefer) on the files extracted from the image. But if you use specialized compressors it might be a completely different story (especially on CDs with just multimedia or with a lot of different content like games or backups of personal data).
What I don't know is how image formats like ISO and BIN are set up, if they put a lot of "packaging" around files or don't store a single file as one block, then there might be some additional gain.

But I don't know of any tool that will let you extract information about the layout of the image.

http://homepage.ntlworld.com/director/cod/christondisk.htm