When I had painter 6 and I had a black and white picture and I wanted to make the white bits perminantly transparent on the layer( so I could just have the black bits)
I used to be able to click on the mask layer then go into the mask section and select ; automask ; then image luminance and it would turn the white bits clear. (although the black was washed out but I got round that by sellecting reserve transparency and filling it with black to bring it back)

Now with painter 9 the mwthods have changed. I've been searching for hours to find how to do it. There is thing called shadow map which makes the white transparent but its not perminant.

can anyone help me?