An efficient image data format for lossless compression and its application to interactive viewing

The purpose of this paper is to present a new data structure for viewing large size medical images. The data structure is specifically designed suitable for lossless compression and viewing images interactively even when the channel bandwidth is limited as low as those of modems. Our data structure has been tested on several 2 K/spl times/2 K images by using various baud rates from 9600 to 28800. The thrust of this paper is two fold. First, browsing large image data files through limited bandwidth channels requires progressive transmission. Using conventional data structures, 1/3 more memory space is required to build the hierarchical structure. Our data structure utilizing two-dimensional DPCM embedded with hierarchy does not require extra memory space to build the structure for progressive transmission. The second important aspect of the data structure is the local zooming capability of the data for interactive viewing. This is achieved by rearranging the transmission order of image data so that the data in the region of interest can be transmitted first with the rest of the information on hold to be sent later.