Dynamically changing the resolution in print processor

I am trying to implement dynamical changing of printer driver resolution in
printing into print processor. So I had changed dmPrintQuality and
dmYResolution, and I could get the near result, but it was not what I wanted,
because the looks had much shaggy as if it were just made by changing scale
of the bitmap of original resolution without interpolating.

Of course if the driver resolution was set to its desired value at first,
the looks of printing is normal and doesn't have any shaggy.

I want to get the same result with print processor dynamically changing the
driver resolution, but could I do this kind of things in print processor?

Thanks