Amplification of nonclassical light in phase space

The scale transformation acting on P-functions associated with density operators of light is introduced as an amplification process for single-mode radiation fields. The P-amplification does not always yield a physical state out of the given nonclassical state; in particular, there are some restrictions on the degree of amplification that depend on how nonclassical the initial state is. The exact constructions of P-amplified density operators for two- and three-dimensional Hilbert spaces are carried out explicitly.