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how to compress? .zip always same size???

dougens

dougens

macrumors member
Original poster
Aug 22, 2007
88
0
London
I am using stuffit (dropstuff) to compress a folder of photos (28mb) to semd via email to windows user.

I tried using the mac ctrl menu compress and it creates a zip but of the same size. I tried using dropstuff on stuffit to compress but .zip is the same size as original too!!

Please help driving me crazy - sorry so simple!!!!

I am running 10.5.8 (ignore signature below) on 15inch mbp (not the new one)

thanks
 
GGJstudios

GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
Some things don't compress as much as others. Some little or none at all. For example, text documents will compress a lot, while movies and photos, not so much.
 
MisterMe

MisterMe

macrumors G4
Jul 17, 2002
10,709
69
USA
dougens said:
...

I tried using the mac ctrl menu compress and it creates a zip but of the same size. I tried using dropstuff on stuffit to compress but .zip is the same size as original too!!

...
Click to expand...
I assume that your photographs are in JPEG (.jpg) format. This is a lossy compression format. Images compressed with this format cannot be compressed further using a lossless compression scheme like .zip.
 
J

jkane08

macrumors member
Jul 28, 2008
69
0
Philadelphia
(not trying to hijack your thread)

completely off-topic... for the most part; (but my interest has been piqued)

since movies are already compressed, how do you uncompress say an .avi or .mpg to it's original format, or is this impossible?

lossless audio and movies and lossy digital, it's all confusing to me.


not trying to hijack the thread, but quarterswede you got me interested
 
J

jackerin

macrumors 6502a
Jun 29, 2008
870
35
Finland
jkane08 said:
since movies are already compressed, how do you uncompress say an .avi or .mpg to it's original format, or is this impossible?
Click to expand...
No. Lossless can be decompressed to the same quality as the source, lossy can not. (There are lossless video codecs that you can put into AVIs, but you won't find many of those online.)
 
eXan

eXan

macrumors 601
Jan 10, 2005
4,731
63
Russia
You don't compress images with zip. What you can do is open them in any image program (even Preview) and export using lower resolution and/or quality.

Same goes with video and music.

jkane08 said:
completely off-topic... for the most part; (but my interest has been piqued)

since movies are already compressed, how do you uncompress say an .avi or .mpg to it's original format, or is this impossible?

lossless audio and movies and lossy digital, it's all confusing to me.


not trying to hijack the thread, but quarterswede you got me interested
Click to expand...

You can't. The only way to get "full" quality out of "compressed" music is to decode lossless. Some of the most popular lossless formats are .flac, .ape, .alac

EDIT: old thread... I knew something was up ;)
 
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