A fast scanline algorithm for a raster-scan graphics display is proposed based on an observation that a sequence of successive image frames in animation mostly consists of still objects with relatively few moving objects. In the proposed algorithm, successive images within a given time interval are generated using an interpolation of two images generated at the start and end time of the given time interval. Experimental results have shown that a speedup factor of 3.2-12.9, depending on the percentage of the moving objects among all objects, is obtained using the algorithm, compared to the conventional scheme that does not use the frame-to-frame image coherence.