With version 12.0 of its popular file compression package, Corel-owned WinZip Computing says it is targeting digital media users, and has added new compression algorithms, as well as support for new file formats.

The Pro version allows system administrators to customise the Microsoft installer so that password policy and encryption methods available for users can be defined prior to installation.

We looked at the Professional version of WinZip 12.0, installing it on Windows XP Professional and Windows Vista Ultimate. The general appearance of the interface differs little from the previous version, aside from several minor refinements.

The major addition is on the compression front, where WinZip has beefed its package up with algorithms targeted at specific file formats. The JPEG picture format now has a custom compressor, which can also be deployed to pull images straight off the camera, as well as orient them correctly.

File sizes can be drastically reduced, and WinZip claims that a 20-25 per cent reduction is possible with no loss of image quality. Users can't specify JPEG compression implicitly, they have to select 'best method for each file type' and leave WinZip to deal with the file depending on the file extension.

Also the 20-25 per cent reduction in file size figure is probably an average, since we saw file reduction percentages well in excess of 25 per cent.

Since WinZip uses only so-called 'lossless' compression to reduce JPEG file sizes, no loss of image quality can happen, since no bits or information are discarded during the compression process. This means that when the image is extracted, it should be an exact copy of the file originally compressed.

WinZip 12 also adds Lempel-Ziv-Markov chain algorithm (LZMA) compression to those already wired in. We reviewed the compression algorithms on how quick they were to archive and extract data, together with how much space they saved when compressing files.

We used two data sets containing around 1GB of data, with a mixture of file types - one with normally compressable files, the other with normally incompressible files.

WinZip 12 has seven compression methods available, with three not being compatible with earlier WinZip versions ('best method for each file type', Enhanced Deflate and PPMd) and four which give compatibility with earlier WinZip releases (bzip2, Legacy [WinZip 2.0], LZMA and SuperFast methods).

It is the 'best method for each file type' compression method which hides the actual algorithms – for example, the new JPEG algorithm, which processes files with specific extensions, such as xxx.jpg, xxx.wav, and so on.

Our test results show that the quickest methods tend to save the least amount of file space. The Legacy (WinZip 2.0) and SuperFast methods were the quickest compression algorithms, and the 'best method for each file type' and LZMA methods saved the largest amount of space, but took seven times longer.

If disk space is not a problem, then the quicker methods should be used; if time is the problem then you could use the methods which take longer. Or, you could use WinZip's 'Create Job' option to set up a task which would run in the background, providing your processors and hard disk are up to the job.

Encrypting files had little to no effect on how long WinZip needed to process the data, and no effect on how much disk space it needed.

When extracting files from WinZip archives, the compression methods which originally took longer to process the data, were also the ones which took longest to extract it.

For example, WinZip could extract files from LZMA-processed data four times faster than the time it took to create the archive.

With the 'best method for each file type' option, the extraction time was around twice as fast as the time taken to create an archive with files which were normally incompressible. With normally compressible files it was five times as fast.