The effectiveness of direct volume rendered images depends on finding transfer functions which emphasize structures in the underlying data. In order to support this process, we present a spreadsheet-like constructive visual component-based interface, which also allows novice users to efficiently find meaningful transfer functions. The interface uses a programming-by-example style approach and exploits the domain knowledge of the user without requiring visualization knowledge. Therefore, our application automatically analysis histograms with the Douglas-Peucker algorithm in order to identify potential structures in the data set. Sample visualizations of the resulting structures are presented to the user who can refine and combine them to more complex visualizations. Preliminary tests confirm that the interface is easy to use, and enables non-expert users to identify structures which they could not reveal with traditional transfer function editors. Short paper
