Transformed? Possible depending on one's definition. The pulsating DC output of rectifier diodes can be 'transformed' by way of additional capacitors to form voltage doubler/tripler/etc. circuits.
Technically correct, if the pulsating DC has a way of returning the current on the downward swing. Although the doubler, etc. doesn't care about the DC operating point, current must flow in both directions from the source.
Technically correct, if the pulsating DC has a way of returning the current on the downward swing. Although the doubler, etc. doesn't care about the DC operating point, current must flow in both directions from the source.
A doubler requires current flow in both directions. A pulsing DC from a rectifier can only supply current in one direction (usually positive). The diodes block the current flowing the other way. As you say, the center voltage doesn't matter. To drive the doubler's rectifiers, you need current flow in both directions.