When you use Fireworks to edit images, the images in your web pages are normally exported by Fireworks from a source PNG file. When you open an image file in Dreamweaver to edit it, Fireworks automatically opens the source PNG file, prompting you to locate the PNG file if it cannot be found. If you prefer, you can set preferences in Fireworks to have Dreamweaver open the inserted image, or you can have Fireworks give you the option of using the inserted image file or the Fireworks source file every time you open an image in Dreamweaver.