Interactive tools for image segmentation

Interactive tools for segmenting 2-D and 3-D images are presented. These tools allow a user to quickly revise a segmentation result obtained from an automatic method. A thresholding technique is described that finds a unique threshold value for each homogeneous region in an image. The threshold value is found such that variance in the region is minimized under change in the threshold value. Curve- and surface-fitting methods are described that can accurately represent a region boundary in 2-D or 3-D with a parametric curve or a surface, respectively. A curve or a surface is optimized to minimize the number of control points representing a region with a prescribed accuracy. The optimized curve or surface is then revised by moving its control points interactively. Once a curve or a surface is found to accurately enclose a region of interest, it is quantized to produce the final 2-D region contour or 3-D region surface. These interactive tools can be used to revise unsatisfactory results obtained from any automatic segmentation method.