The present disclosure provides a technique to obtain a tilt state occurring between an image capturing unit and a print image having additional information embedded in it without using the visible image. In the technique, an image of a print image in which additional information having a specified frequency characteristic is embedded is captured using an image capturing unit to obtain captured image data. A frequency analysis is performed on partial image data corresponding to a specified area in the obtained captured image data, to obtain distance information on a distance between the specified area and the image capturing unit. Inclination information indicating a state of a relative inclination between the image capturing unit and the print image is obtained based on this distance.