1. An image processing method for performing a projection transformation on a captured image, comprising: a region setting step for setting first regions by partitioning an image obtained subsequent to transformation of the captured image by lines parallel to a horizontal axis and a vertical axis passing through an origin; and a transformation step for transforming second regions prior to the transformation of the image, which correspond to the first regions set by the processing of the region setting step, into the first regions by a projection transformation, characterized in that the first regions are set by the processing of the region setting step so that the first regions do not contain the horizontal axis or vertical axis.