1. An image processing apparatus comprising: an imaging operation state acquiring unit that acquires imaging operation state information representing imaging operation states at the time of an imaging operation for a plurality of images that are consecutively generated in a time series; an image processing unit that performs image processing, which is used for generating a synthesized image representing transition in a specific operation of an observed subject included in the plurality of images, based on the acquired imaging operation state information for the plurality of images; and an image synthesis unit that generates the synthesized image by synthesizing the plurality of images for which the image processing has been performed, wherein the imaging operation state acquiring unit acquires a rotation angle with an imaging direction at the time of the imaging operation being used as an axis as the imaging operation state information, wherein the image processing unit performs a rotation process for each of the plurality of images in accordance with the rotation angle that is specified by the imaging operation state information, wherein, in a case where the rotation angle specified by the imaging operation state information is a predetermined angle, the image processing unit performs the rotation process for each of the plurality of images, and wherein, in a case where the rotation angle specified by the imaging operation state information is not the predetermined angle, the image processing unit does not perform the rotation process for the plurality of images.