Advanced On-board Image Compression in Conjunction with Cloud Detection for Micro-satellite Optical Imaging

In this paper we propose two improvements to standard JPEG (Joint Picture Expert Group) coding that can improve the compression ratio achieved for compressing remote sensing images obtained by sensors on-board micro-satellites by more than 39-60%. The first improvement consists in using a quantisation table that has been shown experimentally to be more appropriate for remote sensing images. The second and more significant improvement comes from the use of a novel region growing algorithm that can identify the outer border of a cloud region. The blocks that correspond to cloud regions are subsequently smoothed, as they represent unwanted information for the applications we are interested in, and encoded. The results are demonstrated with the help of several real images obtained by the Surrey University satellites.