Pyvox is a set of software tools being developed for medical image processing with a particular emphasis on brain masking and segmentation of magnetic resonance brain images; tools to support other applications may be added later. These tools are intended to support researchers who need to prototype new image analysis algorithms or to develop automated image analysis tools for specific image analysis applications. The particular sequence of processing operations is specified through a scripting language which can be used interactively or in command files; the language used is an extension of Python.