I've been using FitNesse at work. <http://www.fitnesse.org> Fitnesse captures acceptance tests as tables on wiki page. The information in the table is used to load some code and execute it against the data in the table. Matching expectations are colored green in the table and mismatched expectations are colored red. Even though the fractint code base is difficult to unit test, you could easily make a regression suite using FitNesse so that you can identify when changes to fractint cause it to render parameter sets differently. You generate a reference image using a known good implementation and store that reference image in subversion, along with the fitnesse wiki. Then you create a page in the fitnesse wiki that contains information like: parameter file, parameter set name, and matching? (true/false). Add a bunch of rows into a table for those three items and find the reference image based on the parameter file and parameter set name and you're good to go. This would let you know when fractint can't render parameter sets the same between releases. -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://www.xmission.com/~legalize/book/download/index.html> Legalize Adulthood! <http://blogs.xmission.com/legalize/>