Despite the high download speeds of modern broadband connections, upload speeds remain low.

This is why it's still much quicker to compress large image files before uploading them to the web or emailing them. However, until now, most of us have been limited to using the ZIP format, included with Windows, which doesn't compress JPEG images effectively. Blubox uses what it calls the Blu format to offer a dramatic improvement compared with ZIP. It also allows users to make conventional ZIP archives.

On starting the program, you are given the option to view a tutorial on how to compress files, which is useful if you have not done much image compression before. However, getting started is very simple. Click on 'New', browse for the images you wish to compress, give your archive a name and you're done. A Windows-style interface makes it straightforward to locate and add additional images to an archive.

You can adjust the level of compression and dimensions of the images in your archive depending on how much you want to reduce the file's size. In our test, we took three images of 1.8MB each and compressed them in both Blu and ZIP formats using medium compression and retaining their original dimensions.

The Blu archive reduced the overall file size by 2MB whereas the ZIP archive reduced it by only 29KB, practically no different to how we started. It's clear from our extended tests that Blubox offers significantly better compression of images than the ZIP format. However, compressed images are only useful if they can be de-compressed easily by the recipient.

To de-compress a Blubox archive, a free viewer program must be downloaded and installed on the recipient's PC. Therefore, if you are emailing compressed images as a Blubox archive you must be sure your recipient has the appropriate viewer.

Blubox could save a lot of time sending photographs to family or friends, providing they would be willing to install the software. It is less useful for distributing images to a variety of professional contacts, as unfortunately the format isn't widely used as yet.