SAR Image Compression Using Steganography

Steganograhy is generally used to hide important information in a visible media mostly an image or video. In this paper, a novel scheme serving the dual purpose of concealing and compressing Synthetic Aperture Radar (SAR) images using steganography technique is proposed for aerospace and satellite applications. SAR images represent an important source of information for a large variety of applications around the world especially mapping the geographic area. SAR image compression is very important in reducing the cost of data storage and transmission in relatively slow channels. The problem is that while the volume of data collected is increasing rapidly, the ability to transmit it to ground or to store it is not increasing as fast. Also, while storage densities on archiving media are improving with technology developments, the ability to generate new data is increasing even faster. Thus there is a strong interest in developing data encoding and decoding algorithms that can obtain higher compression ratios and faster transmission of data while keeping image quality to an acceptable level. The imaging radar also called as synthetic aperture radar (SAR), moving along with the path of flight is used to build radar images with the help of backscatters. The radar images built are displayed on the cockpit display and also stored in on-board storage disks. The proposed scheme conceals the confidential SAR images built during the surveillance flight and also enables satisfactory compression of both visible and concealed SAR images. Further compression is achieved by using Lempel-Ziv-Welch (LZW) algorithm. Experimental results show that the stegano-image and the reconstructed images are visually indistinguishable from the original image. This scheme is very simple and can be easily adapted for various image processing applications.