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## Data-flow environments

In our biomedical application, all the data preprocessing and segmentation is implemented in Khoros, a data-flow image processing environment. Khoros provides a network editor; the input data undergo a series of transformations each time a network node is executed by the scheduler (Figure 7). This data flow environment helps the user design an imaging application, as the output of each node can be visualized by connecting it to a visualization module (other packages such as AVS, Explorer, LabView use the same paradigm). However, dynamically setting the range of all the images in a data flow environment is next to impossible. Similarly, writing a macro or a loop in a command-line interface sometimes makes more sense than editing a network of nodes.

These two problems were solved by implementing a Khoros module that executes a VISU script. This approach results in several important benefits. First, it compensates for some of the drawbacks of VISU, e.g. by providing simple ways to extract arbitrary slices. Basically, we rely on modules provided in the Khoros distribution, or write our own modules to filter and transform the raw data. Next, the power of both command-line and data-flow environment can be combined: a command-line interface is provided by a remote controller derived from the `rmt` example of the Tk distribution, which can communicate either with a specific application or send messages to all of them. As a result, the user can rely on the power of visual programming, while being able to rely on a more traditional command-line interface. To our knowledge, this feature is not provided by any other visualization package. Finally, the embedded visualization modules can communicate with each other. For example, the same profile could be extracted in different images and displayed in the same 1D signal viewer. Let us remark that the same approach could be easily implemented in other data-flow environments such as AVS or Explorer.

Next: Volume visualization Up: Hypertools Previous: Image profiles and histograms