Image decoding/decoding method and device

According to the present invention, an image decoding method comprises the steps of: receiving a bit stream; generating a prediction block and a residual block for a current picture on the basis of the bit stream; performing up-sampling on the residual block on the basis of reduced resolution update (RRU)-type information derived from the bit stream; generating a restoration block on the basis of the prediction block and the up-sampled residual block; and performing filtering on the restoration block on the basis of the RRU-type information. According to the present invention, image encoding efficiency is improved and complexity is reduced.