Help with compressing files and folders..

bluefox9er · May 31, 2010

Hi..I am looking for help as to what i am doing wrong when trying to 'compress' a file or a folder. i am trying to upload stuff to my mobile me and to compress it, I am right clicking the photo or folder to 'zip' it. the computer then zips it all up...but the zip file is EXACTLY the same size as the uncompressed file!

what am I doing wrong, please? I am using mac OS X 10.6.3

thanks!

mrplow · May 31, 2010

If it's JPG format images you're ZIPing then they aren't going to get any smaller as they are already compressed. All ZIPing will do is package them into a single file.

As a test create a folder with several large text filts, html files, spreatsheets etc. Then compress that folder and you'll see a bigger difference.

Raz0rEdge · May 31, 2010

AS @mrplow said, certain files get compressed REALLY well (text usually) and others are already compressed..like MP3, JPG..and so on..

Regards

Bill McEnaney · May 31, 2010

You're right, I'm sure. But I can sometimes shrink compressed files by stacking compression. For example, I've compressed a bzipped file with gzip or the other way around. I just haven't tried to stack-compress an image file. Zip's "-9" option tells the computer to try harder than usual to compresses files. Newer versions bzip2 make the machine assume that you want the compressed file to be as small as possible. Be careful, though, because compression-stacking can enlarge the compressed file. The good news is, even if it does that, the uncompressed file will be its normal size.

See all the fun stuff you can do when you prefer a command-line to a GUI?

Raz0rEdge said:
AS @mrplow said, certain files get compressed REALLY well (text usually) and others are already compressed..like MP3, JPG..and so on..

Regards

technologist · May 31, 2010

Bill McEnaney said:
You're right, I'm sure. But I can sometimes shrink compressed files by stacking compression. For example, I've compressed a bzipped file with gzip or the other way around. I just haven't tried to stack-compress an image file. Zip's "-9" option tells the computer to try harder than usual to compresses files. Newer versions bzip2 make the machine assume that you want the compressed file to be as small as possible. Be careful, though, because compression-stacking can enlarge the compressed file. The good news is, even if it does that, the uncompressed file will be its normal size.

See all the fun stuff you can do when you prefer a command-line to a GUI?

Yeah...I'm sure you can redefine the laws of mathematics

Look, if you combine every compression scheme known to humanity, you might get your 10 MB folder full of compressed files down to 9.5 MB...and only spend about an hour doing it. Probably not worth your time.

Bill McEnaney · Jun 1, 2010

Yeah, technologist, go ahead: Gloat, gloat, gloat.

Everybody else does.

My diligent new iMac squeezed hard enough to make my favorite jpeg portrait's eyes bulge. Unfortunately, the poor machine disappointed me by shrinking the 832,029-byte file to lackluster 798,632 bytes. Can't fault the guy for tryin', though, can ya?

technologist said:
Yeah...I'm sure you can redefine the laws of mathematics

Look, if you combine every compression scheme known to humanity, you might get your 10 MB folder full of compressed files down to 9.5 MB...and only spend about an hour doing it. Probably not worth your time.

Help with compressing files and folders..

bluefox9er

mrplow

Raz0rEdge

Well-known member

Bill McEnaney

technologist

Bill McEnaney

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