[kevs]

I just tested using the save archive/zip feature.
Made a folder of 6 jpegs 700 k from 1MB. about 30% savings. is this about right? not much more?

[Ilgaz]

JPEG can't be further compressed unless you switch them to Jpeg 2000.

I guess the 30% part you were able to compress were "resources", e.g. icons or some other compressable data.

Only Stuffit 10 propetioary sitx manages to compress JPEG with an alghorithm one intern guy invented by 30%.. Well you know the deal, some hate or some not, so I just said in case.

(don't shoot me Allume haters)

[Brass]

JPEGs are usually compressed already, so I wouldn't expect very good compression of them. You'll probably get a lot better than 30% on text files, and other non-compressed source files.

[TETENAL]

JPEG already uses compression to store the image data. The more compressed information already is, the less you will be able to further compress it. If you'd take an already efficiently compressed file (like an MPEG-4 movie for example), zipping would get you nothing. The ZIP-Archive might even be larger. If you take a file that is not compressed at all (like a pure text file) then you might save 50% or more by zipping.

[TETENAL]

Originally Posted by Ilgaz

Only Stuffit 10 propetioary sitx manages to compress JPEG with an alghorithm one intern guy invented by 30%.

An intern guy invented that??

I would have shut up and patented the algorithm myself some time after I stopped working there.

[Ilgaz]

I am sure some huge "resources" involved in this case. I would not be surprised if he/she uses Adobe Apps which uses every aspect of HFS+ resources.

[Ilgaz]

Originally Posted by TETENAL

An intern guy invented that??

I would have shut up and patented the algorithm myself some time after I stopped working there.

lol, sell where? RAR labs?

I am sure the person has patent rights for his own too. Thing is- no "other format" (read:open formats) can implement that alghorithm since they should care about backward compatability too.

For example, people using BZIP 1.1 should be able to open BZIP 2.4 archives, it is how open standards works.

On Allume especially, they don't care since their format is already propetioary. So, you compress jpegs (it is a _real_ invention,finally stuffit deserves major version upgrade) and say the recipient "get stuffit 10 expander". After you see the hassle, you send them "self extracting" risking some paranoia You know, .exe file.

Imagine doing such a thing with zip. I think after 3.x, RAR Labs (great for PC btw) stays away from making format "non backwards compatible" too.

BTW- the "Intern info" comes from Slashdot, from an insider or a guy in compression community. What do you say? "Grain of salt" or something

[tooki]

Originally Posted by kevs

I just tested using the save archive/zip feature.
Made a folder of 6 jpegs 700 k from 1MB. about 30% savings. is this about right? not much more?

As others have said, re-compressing compressed files doesn't save much -- sometimes, it can increase total size!

But even if they weren't already compressed files, the compression ratio depends entirely on the contents of the files. I've seen everything from 5% savings to >99% savings. It all depends on what the files are.

tooki

[kevs]

thanks great info!