PURPOSE:To track the contour of a complex image element by one time of tracking by tracking the endpoint of each run in an upper and a lower directions after converting image data to a runlength code. CONSTITUTION:The image data inputted from an input means 1, after being converted to the runlength code by an encoder 2, is stored in a memory 3. A control means 7 controls a tracking means 5, and executes a tracking processing by reading out data stored in the memory 3. In the tracking processing, a prescribed remark point is selected first, and the tracking of the start point of a neighboring run is performed under the run including the remark point. When such tracking is impossible, the start point of the run neighboring on the run including the remark point at the next stage sequentially, and when the tracking of all neighboring runs are completed, the tracking processing is finished. A chain code corresponding to a tracking direction is generated by a generation circuit 5, and it is stored in a memory 6.
展开▼
