Chris mentioned using Tilt Shift which is a live effect and I read his post to mean he had increased the resolution of that effect, having applied the effect to the mould

if you increase the resolution of the effect that is applied to the mould, you indirectly increase the resolution applied to the mould; there is no such feature for the mould tool itself

worth pointing out it will not increase the resolution beyond that of the source image - the issue is that there is some degredation of the source image when the mould tool is applied, this has always been the case with bitmaps; this appears to get round it

@Chris - I checked this out and it seems to work I have my effects set at 300 dpi by default