Tomographic reconstruction is performed of cross-sectional images of downhole or surface multiphase flows containing water (brine), oil, and gas phases. Measures are obtained of digital transmission (or analog attenuation) and also of analog transit time to form two views of the same cross sectional flow in a location of interest in a flow conduit. The measures are then merged by synthesizing a composite image of the multiphase flows. Rather than performing a complex tomographic reconstruction requiring a large number of calculations, measures are also obtained directly from the tomographic pattern which can be used to reconstruct an approximation of the cross sectional flow by the superposition of circles of variable position, radius and density representing flow patterns.