机动目标的逆合成孔径雷达成像原理与算法

对于非合作的机动目标,由于目标相对于雷达射线的姿态和转速难以测定,而且是时变的,因而给逆合成孔径雷达(ISAR)成像造成较大困难.本文讨论了这种情况下成像的一般原理,并对机动性不太大,散射点子回波多普勒变化满足一阶近似条件时,提出了实用算法.实测数据的处理结果说明新算法是可行的.

Fractal Coding for Image Retrieval

Fractal coding has been proved useful for image compression.It is also proved effective for content based image retrieval.In the paper,we present a block constrained fractal coding scheme and a matching strategy for content based image retrieval.In this coding scheme,an image is partitioned into non overlap blocks of a size close to that of a query iconic image.Fractal codes are generated for each block independently.In the similarity measure of fractal codes,an improved nona tree decomposition scheme is adopted to avoid matching the fractal codes globally in order to reduce computational complexity.Our experimental results show that our coding scheme and the matching strategy we adopted is useful for image retrieval,and is compared favorably with other two methods tested in terms of storage usage and computing time.