One cost-free method I discovered – which produces excellent results – is to open a blank word-processing document (which produces an excellent white backdrop), rest the glass slide on the lip of the monitor, and then take a digital photo and then invert the colors with Picasa. You can flip the image (ctrl+shift+h) if you know it is backwards. This works for all but the darkest glass slides and is satisfactory for those who can’t afford professional processing.
