PROBLEM TO BE SOLVED: To realize, in real time, an image split processing for a natural image.
SOLUTION: After a cell i corresponding to each pixel is temporarily initialized to a non-igniting state, a joint weight Wik for eight cells k adjacent to the cell i is calculated, and based on the results of the calculation, a cell pi=1 allowing a self-ignition is determined (a). Next, one self-ignitable cell not yet ignited is selected to prepare a leader cell (b). Then, the leader cell selected by a self-igniting processing is brought in an igniting state (c), an ignitable cell is selected based on the joint weight between the adjacent cells by an ignitable cell detection processing (d), and the cell selected by an ignition processing is brought into an ignition state (e). The operations above are performed repeatedly until any ignitable cell is not selected. When the ignitable cell is not present, an extinguishing processing is performed (f), and an image splitting for one area is completed. These operations are performed until the leader cell becomes absent.