Moment invariants to affine transformation of colours

• A type of color descriptor (called CAMI) to characterize (planar) colour patterns is proposed.
• The CAMIs are invariant to full affine photometric transformations of the 3 colour bands.
• A constructive method is provided to generate CAMIs involving colour moments of arbitrary order and degree.
• The CAMIs can better cope with changing illuminations and white balance changes than most other descriptors.
• The CAMIs are moderately robust against (small) changes in viewpoint of 3D objects.

Most colour descriptors are not robust because they are constructed for simple colour transformations, such as a diagonal-offset transformation. In this paper, a type of colour descriptor is proposed which is composed of rational expression of moments that are invariant to full affine photometric transformations of the 3 colour bands, called a colour affine moment invariant (CAMI). The construction method, based on multiple integrations of colour cores, is intuitive, and it is generic because it can recover existing CAMIs and generate infinitely many new CAMIs as well. Through comprehensive experiments, the effectiveness of one set of newly generated CAMIs is validated. It is shown that CAMIs can better cope with changing illuminations and white balance changes than some typical colour descriptors and are moderately robust against small changes in viewpoint of 3D objects.