Transient radiative heat transfer in a two-dimensional inhomogeneous rectangular medium is considered. The medium is gray, absorbing, emitting and strongly scattering, and bounded by cold, black walls. Inhomogeneous zones of various sizes are placed at different locations within the medium. The incident radiant energy due to a short laser pulse produces a highly transient and unique transmittance, which is investigated. The discrete wavelets method is used to solve the corresponding equation of transient radiative transfer. The time dependent transmittance for various inhomogeneous areas and the significance of the size and location of the inhomogeneous zones are computed.