Provided are a bS derivation process and a deblocking filtering method and apparatus using illumination compensation and/or chrominance compensation, such as a multi-view video coding, in a picture coding/decoding process in which a prediction coding is performed. If neither of the two blocks are intra-coded, neither of the two blocks do contain a none-zero transformed coefficient, and motion compensation for the two blocks is performed based on the identical reference frame and the absolute difference between the horizontal or vertical components of the two motion vectors of the two blocks is less than 1, the bS of the two blocks is derived by considering whether the two blocks are coded by illumination compensation (IC) according to an embodiment of the present invention. Specifically, if both of the two blocks are coded by IC mode or neither of the two blocks are coded by IC mode, bS is set as such a value that filtering is unnecessary. On the other hand, if both of the two blocks are coded by IC mode and the blocks have different illumination change values, or only one of the blocks is coded by IC mode, the bS is derived using difference of illumination change values or the illumination change value.