In this paper the most general fractal nature preserving linear transf
ormation is derived starting from the most general linear lossless inh
omogeneous transformation, that is the Special Affine Fourier Transfor
m, (SAFT). It is known that the SAFT is simply related to paraxial opt
ical signal processing operations. The transformation's properties are
discussed in relation to recent optics literature regarding linear tr
ansformations, fractal functions and self-reciprocal functions. It is
indicated how these results further generalise results previously pres
ented in the literature regarding some non-linear transforms of fracta
ls and prefractals.