Color-based moment invariants for viewpoint and illumination independent recognition of planar color patterns

This paper contributes to the viewpoint and illumination independent recognition of planar color patterns such as labels, logos, signs, pictograms, etc. by means of moment invariants. It introduces the idea of using powers of the intensities in the different color bands of a color image and combinations thereof for the construction of the moments. First, a complete classification is made of all functions of such moments which are invariant under both affine deformations of the pattern (thus achieving viewpoint invariance) as well as linear changes of the intensity values in the individual color bands (hence, coping with changes in the irradiance pattern due to different lighting conditions and/or viewpoints). The discriminant power and classification performance of these new invariants for color pattern recognition has been tested on a data set consisting of images of real outdoors advertising panels. Furthermore, a comparison to moment invariants presented in literature ([1] and [2]) that come closest to the aimed type of invariants is made and new approaches to improve their performance are presented.