1. An image processing apparatus comprising: a superimposition processing unit configured to perform a blending process for a plurality of continuously captured images, wherein the superimposition processing unit is configured to selectively input luminance signal information of a RAW image or a full color image as a processing target image and perform a superimposition process, and performs a process for sequentially updating data that is stored in a memory for storing two image frames so as to enable superimposition of any desired number of images.