7Zip lossless or lossy?

[Martin 71]

Hey, I'm compressing some backed up images of my games, and it's taking up a little too much space for me on my backup partition. Is 7Zip's ultra compression lossless or lossy

 

[elel]

I really don't see how they could send out a general compression tool with lossy compression. I can't say for sure, but I see no way that it could be lossy. If you're worried, compress a folder, uncompress it, and compare the hashes.

 

[gtvr]

pretty darn sure it's lossless

 

[Martin 71]

quick question... how do I compare the hashes?

 

[elel]

This looks like a windows gui based program to do it - if you can run it on your version of windows. Honestly, I've never done this under windows so I don't have any guaranteed method. On the other hand, I found this quote on the 7-zip sourceforge forum:

Generic compression formats, like 7z, rar, and zip, contains file of any kind, so they must rely on lossless compression to guarantee any input bit is extracted exactly the same with no loss of information.

So I guess that that answers the question just the way I though it would be.
This is the thread that I pulled the quote from - read the OP's second paragraph; it made me :lol: :lol: :lol: :lol: :lol:

 

[Martin 71]

Best answer selected by Martin 71.

 

[Mousemonkey]

This topic has been closed by Mousemonkey