A memory device, a signal processing apparatus, and an image signal processing apparatus and signal processing methods configured to perform matching processing with a small amount of calculation and accurately detecting motion vectors, provided with a memory for converting by using a feature including a pixel value in a certain block range having a focused pixel at its center as an address based on information of a reference frame stored in a second frame memory; and a matching portion for reading storage information of the ME memory by using a feature of a focused pixel included in information of a current frame supplied from a first frame memory as a feature address, calculating a distance between the focused pixel in the current frame and a feature address (position coordinates) read from the ME memory, and detecting differential coordinates based on position information having the minimum distance from a plurality of candidates as motion vectors of the focused pixel.