1. An image processing apparatus characterized by comprising: moving-image input means for receiving a captured moving image captured by an image capturing apparatus; transformation-information calculating means for calculating, on the basis of a first captured image included in the captured moving image and a second captured image positioned subsequent to the first captured image along a time axis of the captured moving image, transformation information relating to the first captured image and the second captured image; image holding means for holding, as a history image, individual images including the first captured image and being positioned prior to the second captured image along the time axis of the captured moving image; image transforming means for transforming at least one of the history image and the second captured image on the basis of the calculated transformation information; operation accepting means for accepting a selecting operation of selecting an image to be transformed by the image transforming means; image combining means for combining the history image and the second captured image, at least one of which has been transformed by the image transforming means in response to the accepted selecting operation, to generate a composite image; output means for outputting the composite image; and control means for causing the output means to sequentially output the composite image.