The present invention realizes a function equivalent to an optical half-ND filter electrically and incorporates this function in an image-signal processing system, thereby to compress the dynamic range of images, both effectively and flexibly. The present invention provides an imaging apparatus including an imaging unit that photographs an object, thereby to generate a video signal, a pattern-generating unit that generates a two-dimensional gradation pattern, and a multiplying unit that multiplies the video signal by a gain that corresponds to the two-dimensional gradation pattern.