Poser can read tiffs, and has long (perhaps always) been able to. However, before Poser 7 it couldn't read 16-bit per channel tiffs as used for the M4 displacement maps (in orer to avoid visible stair-stepping on large displacements), There was a trick in Poser 6 to combine two 8-bit per channel tiffs in the material room (since Poser could handle 16-bit per channel images internally) to achieve the same result, but that of course requires a completely separate set of files.