A 3D intensity model based on spherical harmonics for automatic 3D segmentation of heterochromatin foci

We introduce a 3D model-based approach for automatic segmentation of 3D fluorescent heterochromatin foci from microscopy images. The approach employs a new 3D parametric intensity model based on a spherical harmonics (SH) expansion and can represent foci of regular and highly irregular shapes. By solving a least-squares minimization problem, the new model is directly fitted to the 3D image data, and the model parameters including the SH expansion coefficients are estimated. The approach has been successfully applied to real 3D microscopy image data and has been compared to previous approaches.