In a signal processing apparatus for an imaging apparatus, a motion vector generator divides a frame of interest of frames of time-series RAW data that constitute video into macroblocks and generates motion vector information between a macroblock of the frame of interest and a macroblock of a reference frame that corresponds to the macroblock of the frame of interest, the reference frame being a frame preceding the frame of interest. A determination unit determines whether the macroblock of the frame of interest is a target of development, based on the motion vector information. A development unit develops a macroblock that is determined as being the target of development, to generate a frame of interest. A composition unit copies and composites the developed macroblock of the reference frame based on the motion vector information to a position of a macroblock of the frame of interest that is determined as not being the target of development.