Well... according to Roman. He was nice enough to share his technique on the dpreview discussion board:
1. Process in ACR at the largest MP size allowed for your camera. 360PPI.
2. Enhance contrast (USM 20/30/0), increase saturation (if needed), sharpen (USM 300/0.3/0) and add noise to reduce the 'watercolor effect' of the next step (0.8% Gaussian monochromatic).3. Interpolate to 60”x40” at 240 ppi using the Fred Miranda SI Pro 2 plug-in.
4. Down sample it to your desired size (I recommend maximum size of 20”x30” for 6mp….and 30”x45” for 10/12+MP) @ 150 ppi using bicubic sharper.
5. For shots with smoother detail…add noise (3% Gaussian monochromatic) for yet more natural lookif you have a lot of smooth surfaces (No problem with detailed landscapes)
there might be slight variations in the 'usm' and 'add noise' settings …adjust these to taste.I use smart sharpen for the second piece, but USM works fine.
Now....my stronger reccomendation is to just to PP up to the point just before uprezing.....and send it to a shop that has a LightJet or a quality RIP on a printer like an Epson 9800....they will uprez better than you can even with these technique....(its a small diffrence but it is better)Roman
His album's here: