1. An image capturing apparatus for generating a synthesized image from a first image and a second image obtained by continuous image-capturing, the image capturing apparatus comprising: a displacement detection unit configured to detect a positional displacement between the first image and the second image; an image-capturing mode determination unit configured to determine whether the first image and the second image were captured in a still image mode; a control unit configured: to direct the displacement detection unit to detect the positional displacement between the first image and the second image using a first displacement detection method in response to a determination by the image-capturing mode determination unit that the first image and the second image were captured in the still image mode; and to direct the displacement detection unit to detect the positional displacement between the first image and the second image using a second displacement detection method in response to a determination by the image-capturing mode determination unit that the first image and the second image were not captured in the still image mode, wherein the second displacement detection method is different from the first displacement detection method, the first displacement method includes the use of local motion vectors to detect the positional displacement between the first image and the second image and the second displacement detection method includes the use of a frame motion vector to detect the positional displacement between the first image and the second image; and a synthesis unit configured to generate the synthesized image by synthesizing the first image and the second image based on the detected positional displacement.