A novel algorithm that permits the fast and accurate computation of geometric moments on gray-scale images is presented in this paper. The proposed algorithm constitutes an extension of the IBR algorithm, introduced in the past, which was applicable only for binary images. A new image representation scheme, the ISR (intensity slice representation), which represents a gray-scale image as an expansion of several two-level images of different intensity values, enables the partially application of the IBR algorithm to each image component. Moreover, using the resulted set of image blocks, the geometric moments’ computation can be accelerated through appropriate computation schemes.