Abstract: In a method of segmenting an image a first seed pixel unit is selected from a first group of pixel units in which the pixel units all have substantially the same grey-level intensity. The grey-level intensity of said first pixel unit is compared with the grey-level intensity of each of selected adjacent pixel units of said image and those pixel units with grey levels within a selected range arm assigned as a pixel unit of the same region as said first pixel unit This comparison process is repeated for each of the pixel units in the image, those already having been assigned being ignored. A further seed pixel unit is selected from a further group of pixel units in which the pixel units all have substantially the same grey-level intensity and the comparison process repeated for all of the unassigned pixel units. Further seed pixel units are selected and the comparison process repeated until all the pixel units of the image have been assigned. A watershed transform is then applied to provide the segmented image.