Resolution mosaic EM algorithm for medical image segmentation

Multiresolution analysis is an established part of the human vision system. It builds different representations of an image with a spatial resolution adapted to the size of objects of interest and to its level of relevance. Multiresolution analysis is an efficient tool for image segmentation. It allows the processing of global features as well as local features in a corresponding proper scale. Furthermore, it simplifies the segmentation process, accelerates the computation, and improves the results. In this work we propose a segmentation algorithm that is based on the multiresolution analysis for the magnetic resonance images of the human brain. It has been evaluated against known algorithm from the literature. The image subject to segmentation is preprocessed to be represented in a mosaic of different resolutions, based on the distribution of the information contained in the image. Then the conventional EM algorithm is applied for the segmentation.

1. Introduction

The human vision system segments an observed scene. One does not see a complex scene, but rather a set of objects. The importance of the process of visual segmentation by grouping is claimed by the Gestalt theory [1] as an early step in the analysis of a visual scene. The segmentation is an unconscious activeness by the human observer. However, in the computer vision system it is computationally expensive and a logically non-trivial task. In addition to the segmentation process the principle of multiresolution is an established part of the human vision system [2]. It can build different representations of an image with a spatial resolution adapted to the size of objects of interest. An observer describes many scenes in all its particulars for the objects in the foreground and in general terms for the background. If we may use the word resolution in conjunction with the word detail, the fine details are expected to be expressed by an observation with a high resolution, the global information by a low one. Thus, a scene can be said to be observed in multiresolution.