Thanks for the quick reply, Redrobes. I downloaded and installed the latest version. However, I'm still having issues with the colour file. It occurs to me that perhaps I have misinterpreted what the colour file is. I was assuming it is just a coloured version of the bump map, whose colours at each point are used to shade that point, but judging by your reply that's not the case. Sorry if this topic has come up before - I can't seem to find any explanation elsewhere. Can you let me know what the colour file should be like?