DVD Demystified

Essentials of DVD Production
509
rather than one-color subpicture highlights. You can even do fancy motion
highlighting such as flaming or spinning buttons, but it’s much slower on
many players. It will also cause problems on PCs, since moving a mouse
over the button will usually not cause the action highlight effect. If you use
action buttons, be sure to test them on more than one computer.
Do you want to idle out? That is, do you want the menu to automatically
jump somewhere else after a particular amount of time? If so, choose a long
timeout period. Make sure the menu doesn’t time out while the viewer is
still reading it.
Menu Creation Menus are produced with a still or motion video background
and a subpicture highlight overlay. The actual “art” of the buttons
is usually in the video background, while the highlights are used to color or
surround the currently selected button (see Figure 12.2). One of the tricky
parts of menu creation is implementing the subpicture highlights. There are
essentially three ways to create highlights: as a separate color-coded
graphic, as layers in a Photoshop file, or directly in the authoring system.
Four highlight pixel types exist (see Chapter 6 for details). The background
pixel type is always transparent for the video to show through the
pixel. When using separate graphics, the background pixels are usually
mapped to white by the authoring system. The other three pixel types can
be used for highlight effects. These are usually mapped to blue, red, and
black in separate graphics. The four pixels types have one set of colors and
transparencies when the button is highlighted, and a separate set of colors
and transparencies when the button is activated. This means you can use
the same shape for highlighting and activating, but with different colors, or
you can use different shapes by having the activation pixels be transparent
when the button is highlighted, and the highlight pixels be transparent
when the button is activated. Since activation lasts less than a second, you
may decide it’s not worth creating separate graphic designs.
The upshot is that you can use three colors (with three transparency levels)
for button highlighting. Unless you do some clever antialiasing or you stick
with rectangular designs, your highlight graphics will look rough and jaggy.
If you use the auto action feature of DVD to create “action buttons” or
“24-bit rollover buttons,” you must make a separate graphic for each highlighted
button. That is, if the menu has 6 buttons, then you have to make 6
graphics, each one with a different button in its highlight state. Each version
is actually a different menu page that is automatically jumped to when
the user changes the button selection.
When you lay out a menu, consider interbutton navigation. The user has
four directional arrow keys to use in jumping from button to button. Try to