Patent ID: 8548254

Claim:
An image direction determining device for determining an up-and-down direction of an input image, comprising: an object candidate detecting means for detecting an object having a fixed shape or arrangement, of which a definite slant angle with respect to the up-and-down direction can be detected, and of which a definite angle can be detected from its shape or arrangement, as an object candidate from the input image; a similarity degree calculating means for calculating a degree of similarity between the object candidate detected by the object candidate detecting means and a pre-stored registration object; and an up-and-down direction determining means for performing weighted averaging of the slant angles with respect to the up-and-down direction in input images of the object candidates detected by the object candidate detecting means with the similarity calculated by the similarity degree calculating means assumed to be a weight, and outputting its weighted average as a slant degree with respect to the up-and-down direction of the input image.