Pictures - PSD (Highly Compressible)

Compression Rate

The best compressor of this fileset was WinRK again. It astounded us by reducing the fileset size to just under 90MB, even at the fastest setting! That's a space saving of over 110MB. Very impressive. Even the closest contender, 7-Zip, could only reduce the size of the archive by 95.6MB.

The worst compressor, by far, was ARJ32. It only managed to reduce the archive size by 42.2MB or 21%.

Compression Speed

When it came to compression speed though, the trio of ARJ32, gzip and WinZip were the fastest compressors. They delivered compression speeds of about 16MB/s. WinRAR also did pretty well, with a compression speed of 13.6MB/s. WinRK was, again, the slowest compressor tested. It took almost 3 minutes to complete the test.

Compression Efficiency

The compression efficiency rating is a simple way to evaluate the efficiency of each data compressor. This way, we can see which compressor can save the most space in the least time.

Please note that a higher efficiency rating does not mean the compressor is better. It just means the compressor has a better compression-to-speed ratio. A more efficient compressor is, of course, always more desirable than a less efficient one.

gzip and WinZip were the most efficient data compressors when it came to Photoshop files. Their super-fast compression speed more than made up for its average compression rate. WinRAR came in a close third place.

7-Zip, Squeez and WinAce were amongst the most inefficient compressors in this test. But the most inefficient compressor was WinRK. The really long time it took to compress the fileset completely offset the amount of space saved.