Oo.....i found 1 to compress my PSP ISO file into smaller 1. It compress it almost 50% smaller in size.
ISO's are already compressed. If you recompress it, with a specific ISO compressor, you might get <10% diff. Else any other compressor approximate 5%. I wouldn't recommend spending any money on it. thats what ISO's do for you already
its free ware spec for psp...not necessarily a compressor..but strips the iso diwn to wat u need...works dif than say winrar compressing a normal iso..
If you only want to reduce the file size,you have the easy way: use winrar (best compression option).Also is the hard way,but one of the best compresion results: use UHARC. I recomend you UHARC,for example you can compress 4gb to 200mb...
lol when I read compressed ISO.. I immediately thought about PSP.. xD. know formats... CSO.. pretty good compression Dax... compresses very well JSO.. bigger than CSO.. but games run smoother.