Image compression method and apparatus using a related group Four tree partitioning system

Image compression procedure based on a conditional tree Four group dividing method comprising the steps of: (A) inputting image data of a frame unit or a field unit by the main block units of a predetermined size, (B) generating a characteristic value for each block and of selective division data, which depend on whether sequential four-cluster dividing operations for the main block in a selected one of a plurality of sub-block types in accordance with an image type of the main block type to be carried out or not, as a four-group tree data, and (C) outputting a four-group tree map that are designed according to the selective division data group of the four-tree data and the characteristic value for each block as a bit stream.