The amount and spatial distribution of impurity radiation in the divertor of a tokamak is of fundamental importance for the behaviour of power exhaust, detachment, recombination, recycling and erosion/redeposition properties. Carbon impurity radiation in the divertor is indispensable to reduce the peak heat flux to the strike zones but carbon erosion also limits the lifetime of the target and leads to large tritium retention via co-deposition. In addition to line-integrated spectroscopic measurements, spatially resolved radiation of the various species obtained from tomographic inversion of 2D-CCD camera data is an important tool for diagnosing the role of impurity and hydrogen radiation in the divertor physics.