compressing files

[spnewman]

I often need to e-mail power point presentations which contain numerous scientific images, which can lead to large file sizes >20MB, our e-mail limit is around 10MB. I was advised to use the create archive option from the file menu to create a smaller zip file which could then be opened by the recipient whether they be Mac or PC. However, the zipped version of the file is virtually the same size as the original so i am still unable to e-mail it, how do i get round this problem?
Cheers

Simon

 

[jmgalvin]

Compression will depend on the format of the images. Generally jpegs or tiffs with lzw are already compressed and will not further compress.

If you happen to have a copy of Stuffit on your machine (I have an older one that I run under Classic) you can see if you have Drop Zip. If so, you can set it's prefs to compress already compressed images or not to further compress.

Beware of one problem with zip files. Because so many Windows viruses were spread via attachements - often zipped - administrtators at a lot of companies have set up email to reject or strip zip archives.

If your docs don't absolutely have to be in PPT format, you might try saving as pdf and see if that doesn't reduce things. Thats how I always send image files now. I can usually get 20 megs down to about 2.5 or 3 megs.

Using OSX 10.3.8 on a G4

 

[SamBones]

If you don't mind hitting the Unix command line, see if you have the utilities [tt]gzip[/tt] and [tt]split[/tt]. I don't have a Mac available at the moment to check, but these are common Unix utilities. If you do have them, you can do the following...

To compress and split the file...

gzip -9v mypresentation.ppt
split -b 2m mypresentation.ppt.gz mypresentation.ppt.gz.

This will create 2 megabyte pieces of your file named like...

mypresentation.ppt.gz.aa
mypresentation.ppt.gz.ab
mypresentation.ppt.gz.ac
mypresentation.ppt.gz.ad
mypresentation.ppt.gz.ae
...

Mail them individually. Then, on the receiving side, to put them back together...

cat mypresentation.ppt.gz.* > mypresentation.ppt.gz
gunzip mypresentation.ppt.gz

That will result in a [tt]mypresentation.ppt[/tt] on the destination machine.

I'll confirm the commands tonight when I get home.

Hope this helps.

 

[ObviousTroll]

jmgalvin's got the main point, though - images usually aren't very compressible.

spnewman - a better bet is to find a filesharing service like .Mac's iDisk - upload your presentation to iDisk then email the URL to your recipients. They can download the presentation from Apple instead of out of the email.

 

[duncdude]

As jmgalvin states, the JPEG file format has been designed to squash pictures up as much as possible using a lossy compression method. This affords JPEG's huge compression ratios. There is very little chance that any image is going to be squashed further

SamBones is spot on. Split is available under OS X. If you segment the archive as he suggests, you should be fine. It is included in a bog standard intsall - Applications / Utilities / Terminal
1) type cd [space] then drag the folder containing the files on top of the Terminal window. This should provide the path of the folder to the command line: i.e. cd /Users/duncancarr/Desktop
2) press Return to accept this
3) type pwd and press Return to confirm you are in the correct directory
4) assuming you are now in the right place - now compress the files ...

Alternatively, Stuffit has a segmentation option also (i am pretty certain it does anyway)


Kind Regards
Duncan