  We show that a suitable deformation of the algebra $h_k(1)$ of the creation
and annihilation operators for a complex scalar field, initially quantized in
Minkowski space--time, induces the canonical quantization of the same field in
a generic gravitational background. This discloses the physical meaning of the
deformation parameter $q$ which turns out to be related to the gravitational
field. The thermal properties are re-obtained in this formalism, and the
application to Schwarzschild and Rindler space-times are carried out.
