Scanning paths for lossless compression of pseudo-color images

Pseudo-color images are widely used on World-Wide-Web (WWW) to reduce file storage, RAM, video memory buffer space, and to speed up data transfers. A pseudo-color image consists of indices and indices are stored in a file with raster scan order. The investigations on different scanning patterns in filing of indices showed that further improvements on compression are possible. In this paper, we propose a lossless compression technique based on various scan patterns along with Burrows-Wheeler transformation and inversion rank. We show that proposed technique yields better compression gain than well-known techniques such as GIF, PNG and others on pseudo-color images.