An Intensity-Space Domain CFAR Method for Ship Detection in HR SAR Images

Synthetic aperture radar (SAR) is an indispensable and extensively used sensor in ship detection. As high-resolution SAR introduces more spatial details into images, this letter proposes an intensity-space (IS) domain constant false alarm rate (CFAR) ship detector to make good use of this information. The method fuses intensity of each pixel and correlations between pixels into one characteristic, i.e., IS index. All the detection procedures center on the calculation and analysis of IS index. First, a new transform maps an image into a new IS domain. Structures like ships and wakes are enhanced in IS domain. Second, a CFAR detector picks up high IS index pixels. Third, a chain of target features is checked to screen out false candidate target pixels. Also, enhanced wakes are taken to improve detection results. Experiments on real SAR images validate that the proposed transform does enhance these structures and the whole algorithm is of good performance, especially in the case of low-contrast targets.