In this section a new structure preserving noise filter, closely related to the SUSAN feature detectors, has been described. Without needing to formulate a rigid model of the image, only those sections of the local image structure which are part of the ``same region'' as each pixel are used to form an estimate of that pixel's original brightness. Quantitative and qualitative results show the SUSAN noise filter to be better at reducing noise (whilst minimizing degradation of the underlying image) than other filters tested.