Which format allows higher compression: *.IMG or *.ISO ?

[Guest Frank Callone]

I want to put (resp. wrap) a directory into a CD image.

The compressability of the directory files is high and I want to compress

all the stuff as much as possible.

 

Which format should I choose: IMG or ISO ?

 

Are there tools which allow a higher compression (without creating a *.zip or *.rar

or *.7z archive) ?

 

Frank