a digital video zoom system includes circuitry for writing image samples into a memory at a standard rate and for reading samples from the memory at a reduced rate . samples are read from the memory under control of a digital accumulator which repeatedly adds a value n to a stored value , modulo m , to obtain a new stored value . samples are read from the memory only when an overflow condition is detected in the accumulator . the four most significant bits of the value held by the accumulator are also used to develop interpolation factors which are used to combine successive sample values provided by the memory to develop interpolated sample values which are used to produce the enlarged image . the image is increased in size by a factor of m / n relative to an unmagnified image .