zip file is still too big

Question

Level 1

6 points

zip file is still too big

After I zipped a lots of photos in one file, it showed the original was 30.5 MB, the zipped file shows it at 30.4 MB.

Shouldn't the zipped file be significantly less than the original file?

iMac Intel Core 2 Duo, Mac OS X (10.5.6)

Posted on May 19, 2009 9:20 PM

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Answer 1

dbsneddon

Level 4

1,542 points

May 19, 2009 9:46 PM in response to Deakin Ng

Depending on what software creates the JPGs, you can specify
the amount of compression. The default is usually fairly high
which means that zipping them will not achieve much.
If the compression is chosen to be low then zipping the files
will result in a decrease in size when zipped.

Dave

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Answer 2

dbsneddon

Level 4

1,542 points

May 19, 2009 9:35 PM in response to Deakin Ng

As has been mentioned, JPEGs are already compressed and attempting
to compress them again will not achieve anything. I have seen cases
where attempting to compress compressed files actually creates a zip
file that is bigger than the original contents.
You are stuck with what you have. Why not copy them off to DVD if
you are trying to recover some disk space?

Dave

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Answer 3

Deakin Ng Author

Level 1

6 points

May 19, 2009 9:36 PM in response to Malcolm Rayfield

just one more thing, i use to receive a zip file that filled with jpg and it's compressed from a big file like the zip file was 10mb (good for email), but after i unzipped, it was 30mb~
or any app can do that?

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Answer 4

May 19, 2009 9:22 PM in response to Deakin Ng

If the photos were already in a compressed format, such as JPEG, ZIP won't be able to do much more compression.

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Answer 5

Deakin Ng Author

Level 1

6 points

May 19, 2009 9:30 PM in response to Malcolm Rayfield

than nothing i can do to make it any smaller?

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Answer 6

May 19, 2009 9:33 PM in response to Deakin Ng

Hi,

*"After I zipped a lots of photos in one file"*

Can you do this in several files instead of one?

Carolyn 🙂

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