Lesson 11. Alpha Channels and Masks

In previous lessons, you worked with some of Director's sprite inks. Background Transparent, which you used as far back as in Lesson 1, is a particularly useful ink. A sprite's ink property establishes how Director will display that sprite's image against that of other sprites below it. If you use Copy ink, the default, the image is copied completely. Background Transparent makes a sprite's background color invisible by allowing the sprites on the stage beneath it to show through the background area. Other inks may give you special color effects or, like Blend, blend the whole image with the images below.

Figure . For this project, you'll use inks and alpha masks to blend a text object with an image object in a dramatic animation sequence featuring the Taj Mahal.

Blend is a useful ink. You can set the blend for the whole sprite with values ranging from 0% (no blend) to 100% (blend completely). Sometimes, however, you may need even finer control. For instance, you may want different sections of the image to have different blend values. You may not want the image's center to blend at all, and you may want its edges to fully blend in. You can create such an effect in either of two ways: you can create a second cast member to use as a mask and use a special ink called Mask ink, or you can include the mask as part of the image itself as an alpha channel. You can create masks totally within Director, but you need another paint program to work with alpha channels (Fireworks or Photoshop, for example). In this lesson, you will take a look at both methods.