Segmentation of diseased lungs in CT images is a nontrivial problem. As Active Appearance Model (AAM) has been applied effectively in this field, we propose a new approach for the construction of traditional AAM to segment the lung fields more accurately and efficiently: Matrixes based AAM (MatAAM). MatAAM is based on two-dimensional image matrixes rather one-dimensional vectors. Its appearance matrix does not need to be transformed into a vector prior to computing the appearance parameter. Instead, a covariance matrix is constructed directly using the normalized appearance matrixes and its eigenvectors are derived for the appearance parameter. The experiment results were compared to other landmark-based methods: Snake, Active Shape Model (ASM), AAM and several modified versions of them. For segmentation of lungs especially diseased lungs, MatAAM performed a superior result in both precision and efficiency.
Self-Ensembling Co-Training Framework for Semi-supervised COVID-19 CT Segmentation