ZIP files

Zipping is just one way of compressing files but it’s one of the best and its great for all file types including images. PC and MAC both have native support for 'zipping' and 'unzipping' so it couldn't be more convenient!

When transferring image files over the internet there are 2 clear reasons to use ZIP files.
  1. You can combine multiple images in one ZIP file
  2. File sizes can be much smaller so you save time and bandwidth
Zipping TIFF files will not effect your underlying data because the compression method is 'Lossless' unlike saving as JPEG which uses 'Lossy' compression - That's right - saving as JPEG losses some of the image data and the more you compress a JPEG the more data you loose. Instead Zip up a TIFF file.

Figure 1



ZIP files make image files smaller

This can range anywhere from 5% to 90%.  The reason the range is so big is that the amount of reduction depends on the complexity of your images.

Figure 1 (right) - The full size version of this image is a 50MB TIFF.

If I ZIP it up it shrinks to 46MB equating to a saving of 4MB or 8%.

Not bad......



Now for a more impressive example...



Figure 2

Figure 2 (right) - was also 50MB as an uncompressed TIFF. 

After Zipping it weighs in at just over 5MB! That’s a massive saving of 45MB or 90%!

Both results show that Zipping the file was well worth while.

The difference between the two results is due to the relative complexity of the images. The deckchair shot contains more distinct colours and tones than the illustration. While the illustration looks 'busy' to the eye it actually has a lot of areas that are just one colour and this allows for far more compression.


So -  If you are transporting more than one file over the internet, ZIP them up.  It’s neat and you'll save a fair bit of time and bandwidth.




How to ZIP - Windows Vista example

ZIP compression has been natively supported on the PC since Windows 98 so there is no need to use a separate program. 

Figure 3

  • In Windows Explorer, make a new folder
  • Copy or Move the files you want to ZIP into the new folder
  • Double Click on the new folder to reveal its contents. 
  • Press the CTRL and A keys at the same time to select all the files in the folder. 
  • With the cursor over the highlighted files, Right Click the mouse to bring up the Context Menu. Figure 3 (right) 
  • Select ‘Send To’ and then ‘Compressed (zipped) Folder’.
The ZIP file will be created.  This may take a few minutes if the files are very large.  When complete you will see the new ZIP folder in Windows Explorer.  The default name will be one of the files inside your folder but you can immediately type a more appropriate name such as ‘FamilyName_mmyy’ (the format we like for ZIP files sent to us). You can browse the files in a ZIP folder by double clicking the zip file and browsing the files as normal.

How to Unzip / extract files

How to ZIP - Mac Example Zipping

MAC Context Menu

Figure 4

ZIP compression has been natively supported on MAC since OSX 10.3 so for most of us there is no need to use a separate program The Finder will create a new file named Archive.zip, which you can rename to something more appropriate such as ‘FamilyName_mmyy’ (the format we like for ZIP files sent to us).

How to Unzip / extract files

Simply double-click the icon. The Finder will create a new folder with the same name as the archive file and decompress all the files from the archive in that folder.

Don't ZIP JPEGs

As mentioned above JPEG uses a 'lossy' form of compression so while it can make for small files you do loose data. The more you compress the JPEG the more data you loose. Further more if you try to ZIP a heavily compressed JPEG it can actually grow in size!

Heavily compressed JPEGS are fine for websites but we don't recommend making Fine Art Prints from them. If you really want to use jpegs use the minimum compression/highest quality setting  (In Photoshop this is Quality:12) and don't ZIP them.