> It's a sophisticated interpolation, not so different from linear interpolation: a*x + (1-a)*y

These algorithms are specifically non-linear a far cry from ‘linear interpolation’ unless you want to water down the meaning of interpolation to be so generic it loses its meaning.

Having said all that - the sophistication of the algorithm is beyond the point here as long as what they are generating is substantially transformative (which >99% of the possible outputs are legally speaking).