Patent ID: 7609955
Filing Date: 2009-10-27
Classification: G02B,G03B,H04N

Abstract:
1. An image taking device which adjusts a taken image according to a positional relationship with a subject, said image taking device comprising: an image taking unit operable to take an image of the subject by using a multifocal lens; a distance computation unit operable to (i) compute a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point that belongs to the object, the object being contained in the image taken by said image taking unit, and (ii) compute an amount of change of a distance from said image taking device to the subject based on the computed difference between the sizes of the object; a focal length computation unit operable to compute a focal length of the multifocal lens based on the amount of the change of the distance to the subject; and a focal length control unit operable to control a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed by the focal length computation unit, wherein said distance computation unit is operable to (i) judge which state among states including divergent, steady and convergent represents each optical flow of a plurality of optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object; (ii) extract, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determine, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) compute an average value of the determined differences as the amount of the change.