An information processing apparatus includes an image acquisition unit, a correspondence relation acquisition unit, an image transformation unit, a change calculation unit, and a statistics amount calculation unit. The image acquisition unit acquires a first image and a second image. The correspondence relation acquisition unit acquires a spatial correspondence relation between the first and the second images. The image transformation unit acquires a transformed image by transforming the second image to substantially coincide with the first image based on the spatial correspondence relation. The change calculation unit calculates a volume or area change between the transformed image and the second image based on the spatial correspondence relation. The statistics amount calculation unit calculates a statistics amount for pixel values of the transformed image based on the volume or area change.
