Although characterized by different mathematical definitions, both the Radon and the Hough transforms ultimately take an image as input and provide, as output, functions defined on a preassigned parameter space, i.e., the so-called either Radon or Hough sinograms. The parameters in these two spaces describe a family of curves, which represent either the integration domains considered in the Radon transform, or the kind of curves to be detected by the Hough transform.It is heuristically known that the Hough sinogram converges to the corresponding Radon sinogram when the discretization step in the parameter space tends to zero. By considering generalized functions in multi-dimensional setting, in this paper we give an analytical proof of this heuristic rationale when the input grayscale digital image is described as a set of grayscale points, that is, as a sum of weighted Dirac delta functions. On these grounds, we also show that this asymptotic equivalence may have a valuable impact on the image reconstruction problem of inverting the Radon sinogram recorded by a medical imaging scanner.1. Introduction. The Radon transform (RT) [1] is an important tool in harmonic analysis and inverse problems theory with significant impacts on both group theory and applied mathematics. The classical definition of this transform considers integrals over hyperplanes with specific orientation and distance from a reference hyperplane. In this case, many functional properties of the RT have been investigated, including the characterization of its kernel and range, the ill-posedness of the inverse problem, as well as several inversion formulas and algorithms. The RT has also been extended to integration on manifolds [2], although here important functional and computational problems are still open. In biomedical imaging, RT is the well-established mathematical model for data formation in X-ray Computerized Tomography (CT) and in Positron Emission Tomography (PET) [3,4] and all software tools for image visualization implemented in current industrial CT and PET scanners must realize, at same stage, the numerical inversion of RT.While RT plays a crucial role in image reconstruction, the Hough transform (HT) [5,6,7] provides an important computational technique in pattern recognition. Indeed, HT is widely used in image-processing to detect specific algebraic plane