A method of coding is provided. The method includes comparing a cost between a bilateral reference block and each of a plurality of first and second reference block candidates in the first and second reference pictures to determine first and second refined motion vectors. The first and second reference block candidates are determined based on a step size selected from a plurality of available step sizes. The method also includes selecting a first refined reference block in the first reference picture based on the first refined motion vector and a second refined reference block in the second reference picture based on the second refined motion vector, determining a prediction block based on the first refined reference block and the second refined reference block, and displaying an image generated using the prediction block.