1. An image processing apparatus for exchanging image data, comprising: a feature value extraction unit configured to extract a first feature value included in image data of a first captured image captured by the image processing apparatus; a feature value reception unit configured to receive a second feature value from an other image processing apparatus and to receive identification information of the other image processing apparatus from the other image processing apparatus; a first determination unit configured to determine whether the received second feature value matches the first feature value included in the image data of the first captured image and to determine when the image processing apparatus captures the first captured image; and an image data transfer unit configured to transfer the image data of the first captured image and the identification information of the other image processing apparatus to the other image processing apparatus in response to a determination by the first determination unit that the image processing apparatus has captured the first captured image and there being a match between the first feature value extracted by the feature value extraction unit and the second feature value.