Scanning Color Foregrounds (Overlays)
In animation a color foreground is usually called an Overlay. The scanner doesn’t know that you want the white part of the image to be transparent so it’s going to make it opaque. The best way to get to see through the part of the image that you want to be transparent is to create an alpha channel for the image using a program like Photoshop.
The easy way is to check the Overlay checkbox in FlipBook’s scanner dialog and set a keying value to determine how white something has to be in order to be made transparent. Pure white is 255. The lower you set the number the more the almost white parts of the image will disappear.
We recommend that you add a very slight blur to your overlays to soften the edges where the white disappears.