A new shape descriptor invariant to geometric transformation based on the Radon, Fourier, and Mellin transforms is proposed. The Radon transform converts the geometric transformation applied on a shape image into transformation in the columns and rows of the Radon image. Invariances to translation, rotation, and scaling are obtained by applying 1D Fourier-Mellin and Fourier transforms on the columns and rows of the shape's Radon image respectively. Experimental results on different datasets show the usefulness of the proposed shape descriptor.