—We present a novel and effective algorithm for affinely skewed rotation symmetry group detection from real-world images. We define a complete skewed rotation symmetry detection problem as discovering five independent properties of a skewed rotation symmetry group: (1) the center of rotation; (2) the affine deformation; (3) the type of the symmetry group; (4) the cardinality of the symmetry group; and (5) the supporting region of the symmetry group in the image. We propose a frieze-expansion (FE) method that transforms rotation symmetry group detection into a simple, one dimensional translation symmetry detection problem. We define and construct a pair of rotational symmetry saliency maps, complemented by a local feature method. Frequency analysis, using Discrete Fourier Transform (DFT), is applied to the Frieze-expansion patterns (FEPs) to uncover the types (cyclic, dihedral and O(2)), the cardinalities and the corresponding supporting regions, concentric or otherwise, of multi...