Abstract: In this paper, first, a linear quadtree representation——GD (standing for)representation is given. And its space requirement is the same as CD's. Then, the relations between GD and CD, GD and QC are discussed, and several conversion algorithms, such as matrix to GD, GD to matrix, raster to GD are given. Finally, for 256-level picture, the GD13 method—the voriant of GD is obtained. It's worth mentioning that the space requirement of GD13 method is not more than that of matrix method.