Several sophisticated imaging methods are based on measurements that lead to accessing a finite volume of the 3-D Fourier domain of an interrogated object and subsequent retrieval of 3-D image detail by 3-D Fourier inversion. Examples are found in inverse scattering, integral holography, x-ray and radio emission imaging, crystalography, and electron microscopy.This paper examines a unified approach to all these methods, namely through reduction of dimensionality based on the pprojection-slice property of the multidimensional Fourier transform. We describe two hybrid (opto-digital) computing schemes, one employing coherent light and the other incoherent light, that can be used with these techniques to reconstruct and display true 3-D image detail tomographically. Reduction of dimensionality is shown to provide flexibility in hybrid (opto-electronic) computing by permitting trade-off between the degree of parallel and serial processing employed. It leads to new architectures capable of enhanced throughput and dynamic range and extends the domain of optical computing beyond one and two dimensional signals.