There are a couple of papers you can look at regarding this: Bell and Hopcroft 2008, Gislason and Silva, 2009, Grosjean et al., 2004, Lindgren et al., 2013.

Best regards /Fredrik

works pretty well when combined with Plankton Identifier software

thanks john & alejandro

Following Fredrik, I agree that there are some helpful ZooImage comparisons already published. For example:

Astthor Gislason and Teresa Silva

Comparison between automated analysis of zooplankton using ZooImage and traditional methodology

http://plankt.oxfordjournals.org/content/31/12/1505.full.pdf+html

Jenefer L. Bell and Russell R. Hopcroft

Assessment of ZooImage as a tool for the classification of zooplankton

http://plankt.oxfordjournals.org/content/30/12/1351.full.pdf+html