1. An image processing apparatus for correcting a positional deviation between a plurality of images obtained in time series and performing synthesis processing on the plurality of corrected images, comprising: a motion vector determination unit that determines a motion vector between the plurality of images; an image synthesis unit that corrects the positional deviation between the plurality of images on the basis of the detei mined motion vector and generates a synthesized image by synthesizing the plurality of images subjected to the positional deviation correction; a filter area extraction unit that extracts a filter area in which filter processing is to be performed on the basis of a degree of inconsistency occurring when the positional deviation between the plurality of images is corrected; a filter kernel determination unit that determines a filter kernel on the basis of an imaging condition; and a filter processing unit that performs filter processing based on the filter kernel on the extracted filter area of the synthesized image.