1. An image processing method for performing image processing by an image processing apparatus using a first pyramid including a plurality of template images having different first resolutions and hierarchized in layers according to the first resolutions, a second pyramid including a plurality of target object images having different second resolutions from each other but equal to the respective first resolutions of the template images in the first pyramid and hierarchized in layers according to the second resolutions such that an image similar to a feature image included in one of the template images in the first pyramid is searched for from one of the target object images in the second pyramid by evaluating a degree of layer-to-layer similarity between the first and second pyramids in an order of resolution from the lowest to highest, the method comprising: calculating a degree of local similarity between a point in the feature image and a corresponding point in the target object on a point-by-point basis for each of all points in the feature image; and calculating the degree of the similarity between the feature image and the target object image by determining the sum of the calculated degrees of local similarity and normalizing the sum, the calculating the degree of local similarity including calculating a tentative degree of local similarity between a point in the feature image and a point in the target object image at a position corresponding to the point in the feature image, determining whether the tentative degree of local similarity is smaller than a predetermined value, in a case where the tentative degree of local similarity greater than or equal to the predetermined value, employing the tentative degree of local similarity as the degree of local similarity, and in a case where the tentative degree of local similarity is smaller than the predetermined value, changing the tentative degree of local similarity so as to reduce the absolute value of the tentative degree of local similarity and employing the changed tentative degree of local similarity as the degree of local similarity.