Two independent techniques, X ray absorption and light transmission, are developed and demonstrated for imaging transient saturation fields in thin-slab porous systems. The techniques yield full two-dimensional saturation fields with high spatial and temporal resolution. In the time required to make a single measurement by one of the traditional methods (e.g., gravimetric or gamma densitometry) and entire image consisting of hundreds of thousands of points is acquired by either the X ray or light technique. These methods are also very sensitive, capable of resolving a hundred or more levels of saturation at each of these points. Evaluation of these techniques is accomplished by direct comparison of X ray and light data as well as comparison with gravimetric and gamma densitometry data. Results of the comparison show very close agreement between the four techniques (on average within 5% saturation). These techniques represent useful tools for investigating processes governing unsaturated flow and transport through porous media.