thank you now work. I have changed aa.max from 2 to 4 as value and I see that the rendering time is very high on a little image. in the test image I see that when aa.max=4 there is a little black point. now I go for render a more complex image. I think this evening (or tomorrow....) I'll have something for to compare the images. if the result will be good probably I'll go to study the code(but I haven't many time for the next couple of months..) for insert a customizable aa.max in the photo window.