Automatic Analysis of the Log-ratio Image for the Detection of Multiple Changes in Multitemporal SAR Images

In this paper, we propose an extension of the automatic and unsupervised change-detection method presented in [1]. By analyzing a properly defined cost function, the proposed method allows the automatic detection of the number (zero, one or two) and the values of the decision thresholds associated with changes (if any) in the log-ratio image. This cost function is the minimum value of the criterion function adopted to select the decision threshold in the log-ratio image according to a modified double thresholding Kittler Illingworth (KI) algorithm (implemented under the Generalized Gaussian (GG) assumption for changed and unchanged classes). Experimental results carried out both on real and simulated multitemporal SAR images proved the effectiveness of the proposed automatic method in detecting both the number of changes (the situation of no changes is also explicitly identified) and the related threshold values.