Target detection based on synthetic aperture radar (SAR) images has been a hot topic because of its important application in maritime environment monitoring. Since the scattering fields from man-made targets, such as ships and oil platforms, are generally stronger than those from surrounding sea surface, the intensity-based constant false alarm rate (CFAR) algorithms have been widely established to distinguish targets from sea surface.1–12 However, the detection algorithms based on single-channel SAR data are sometimes ineffective due to various factors, such as speckle noise, the ambiguities of targets, and other strong noise induced by some uncertain reasons. Recently, with the availability of polarimetric SAR sensors, the polarimetric scattering behavior of targets can be described by the scattering matrix, through which features relating to both the intensity and the relative phase can be extracted. Recently, many polarimetric detection algorithms using polarimetric information provided by fully polarimetric SAR are successfully exploited for detecting targets, especially marine targets.7–12 In 12, Novak proposed the polarimetric whitening filter method for target detection. On the other hand, the coherent target decomposition (CTD) theory can also be used to observe ships because the scattering mechanisms of targets are generally different from that of surrounding sea surface. The results in 13 showed that even in low resolution, SAR imageries marine targets can also be distinguished from sea clutter by CTD theory. Generally, the backscattered field from sea surface is dominated by Bragg scattering with low entropy value. However, owing to the complex metallic structures of man-made targets, the scattering field from a man-made target always contains complex scattering mechanisms with higher entropy value. In Refs. 14 and 15, based on CTD theory, polarimetric SAR images were used to detect ships exploring entropy values. Note that the effectiveness of the entropy-based detector decreases with increasing wind speed because the scattering field from breaking waves also contains complex scattering mechanisms with higher entropy value. Although the methods mentioned above have been widely used to detect targets in SAR images, the strong noises induced by ambiguities and so on, which are often mistaken as real targets and cause false alarms, cannot be effectively removed.