In one concept for a webshop I designed a tool where the user could fit clothes on her own image. One problem – images are not transparent, there was always a background, but usually a solid color. Well, the magic wand in Photoshop would be useful, but too many images to go through then and everytime new items are added. So I studied if Flash could be used and voilá: the MagicWand.as was created.
At the moment there is not threshold setting, but that could be added. Click the part of the image you want to change transparent.