Features invariant to affine distortions from the trace transform

We propose functionals which can be computed from the image function, and which can be used to derive features that are invariant to the group of affine transforms. The first step of this computation is the computation of the trace transform of the image. The trace transform is a generalisation of the Radon transform, which computes a functional, not necessarily the integral, along lines tracing the image. Two further functionals computed from the trace transform result in an image feature. The choice of these functionals determines the type of invariance of this feature