Apple DVD Studio Pro 4 - Manual (Page 112)

While the rescaling makes the graphic look correct in the Menu Editor, the shape’s
dimensions look incorrect as shown in the Button Inspector or Drop Zone Inspector. For
example, if you create a square shape that is 200 pixels wide by 200 pixels high, its size
will appear as either 200 pixels wide by 180 high (if applied to an NTSC menu) or 187
pixels wide by 200 pixels high (if applied to a PAL menu), when added to a menu as a
button or drop zone.
Creating Graphics for Drop Zones and Buttons
Assets used in drop zones and buttons do not need to conform to video aspect ratios
because drop zones and buttons can be resized independently in the horizontal and
vertical directions. Additionally, drop zones and buttons support a graphic’s transparency.
This means you can create a graphic with irregular edges, such as a logo, and when it is
assigned as the asset for a drop zone or button, the transparency will control how the
graphic appears.
Similar to graphics used for shapes, drop zone and button graphics are automatically
scaled to maintain their aspect ratio. If you create a square graphic and import it as an
asset for a drop zone or button, it is scaled so that it remains a square graphic in
DVD Studio Pro. See
Shape Aspect Ratios for more information.
Note: To force the drop zone or button active area to match the graphic’s aspect ratio,
press Shift while dragging one of its corners.
Getting Good Results Using Assets That Include an Alpha Channel
A video asset, either still or with motion, that includes an alpha channel can be very
effective when assigned as a drop zone’s asset. DVD Studio Pro composites the asset
over the menu background using the alpha channel to control the compositing.
For best results, be sure the video is premultiplied (also known as shaped). Premultiplied
video will have correct soft and anti-aliased edges when used in the Menu Editor. A
video channel that is straight (also known as unshaped) will have incorrect edges when
composited in the Menu Editor.
If the application you are using to create your assets provides a choice, it is best to
choose premultiplied video.
112 Chapter 6 Preparing Menu Assets