A borehole electromagnetic wave tomographic imagery method suitable for on-the-spot immediate processing is presented in this paper. This method has some unique characteristics; (1) with the row-action (row operation) technique, the tomographic processing can be performed smoothly in the DOS environment with the capacity of merely 640 K; (2) in the process of inversion, the histogram enhancement technique is employed to make postprocessing of gray-scale map, thus raising the signal-to-noise ratio and resolution ratio and improving quality of maps. The software package designed for toinographic processing proves to be quite satisfactory in model inversion and field data-processing.