1. An image processing apparatus, comprising: an input port for receiving a three-dimensional image of an object acquired at a field of view by an imager, the image recording a pose of the object corresponding to the imager's field of view; a classifier module configured to determine, from a collection of pre-defined poses, an estimated pose of the object recorded in the image using a three-dimensional geometric model of the object, wherein the classifier module uses a generalized Hough transform (GHT) to determine the estimated pose, each of the pre-defined poses is associated with a point in a Hough parameter space of the GHT, and wherein the GHT comprises a plurality of separate Hough accumulators, each Hough accumulator is dedicated to a different one of the pre-defined poses, wherein each pre-defined pose of the object comprises a pre-defined position and a pre-defined orientation of the object; and an output port configured to output a pose parameter descriptive of the estimated pose.