An object-based coding apparatus and method for image signals, wherein upon scanning shape-adaptive transform coefficients of an input image signal transformed in accordance with a shape-adaptive transform, only segments containing such shape-adaptive transform coefficients are scanned. In the scanning operation, segments containing no transform coefficient are skipped, thereby reducing the quantity of data being encoded. An apparatus for and a method of object-based decoding of image signals are also disclosed which can decode bit streams generated using the coding method, thereby reproducing image signals.