Waldo, I just use the magic wand tool and set the tolerance so that what I want to mask is selected in conjunction with the invert selection and fill tools - this might take a little fiddling around and it doesn't always work as well as you'd like. You just make your object black and your mask white and that's it. if you need to invert the mask colors use the invert option. If you are working with multible layers flatten the image first and remember to work with a duplicate file so if you mess up nothing's lost. - TJ