1. An information processing device that is connected to a projecting device that projects an annotation image input from an external terminal onto a projection area in which an object and a background are situated, and is connected to an image capture device that captures a first image of the projection area including the object and the background, the information processing device comprising: a detecting unit that detects a first position of the object in the first image captured by the image capture device and a second position of the object in a second image including the object and the background captured by the image capture device subsequent to the first image, and determines, based on the detected first position of the object and the detected second position of the object, a first changed region of the second image at the first position in the second image that is different than a first corresponding region of the first image at the first position in the first image and a second changed region of the second image at the second position in the second image that is different than a second corresponding region of the first image at the second position in the first image; an extracting unit that extracts the first changed region and the second changed region of the second image; and a processing unit that determines whether the annotation image exists in at least one of the first changed region and the second changed region of the second image, and performs processing on the annotation image existing in the at least one of the first changed region and the second changed region of the second image.