Sony On the Streets of New York with the RX!

[Country Parson]

I don't have an RX1 (and have never handled one), but with the RX100, this effect can be applied in-camera, to a file on the SD card. In other words, it doesn't have to be used at the time at which the shot is taken, so you can apply it retrospectively to an image. It works on Raw files too.

It might be worth checking to see whether the RX1 has the same capability.

Yes, the RX1 will do this in camera after the shot is taken. It only offers watercolor or illustration as options.