User`s guide

Chapter 3 Starting Your Project
156
Alpha Channel
Controls how Avid FX interprets alpha information for movie files
exported or rendered from your Avid editor. You can override this
setting for a specific composition when exporting or adding to the
Render Queue.
• Straight Alpha for movies with alpha channels that are not
premultiplied. Straight Alpha displays the area of the image defined
by the alpha channel. The area where the alpha is black (a value of
0) is transparent. The area where the alpha is white (a value of 255)
is opaque. Areas with alpha levels between white and black (gray)
display intermediate levels of transparency. This is the fastest and
best choice for a movie that may be used in additional compositing.
• Premultiplied Black or Premultiplied White for movies whose
alpha channels are premultiplied with solid black or white,
respectively. Some hardware devices may not composite the color
channels correctly if you choose Straight Alpha, resulting in
problems such as aliased text. This corrects that problem. The level
of black or white used depends on whether the
Generate Safe Levels
checkbox is selected.
• Choose Composite over Black or Composite over White to remove
the alpha channels and composite the image over solid black or
white. The level of black or white used depends on whether the
Generate Safe Levels checkbox is selected.
Color Depth Options are 8 or 16 bit. The Color Depth button sets the color depth for
your project. 16-bit-per-channel mode makes a larger range of colors
available. When you work with gradients for film effects or HDTV output,
16-bit-per-channel mode means that transitions between colors display less
banding, and more detail is preserved. Using an 8-bit effect in a 16-bit
project will result in a loss of detail.
To optimize performance, create your effect in 8-bit, save a preset and then
render a 16-bit file for maximum quality. However, you should preview the
final effect to make sure that it appears correct. Even if you work with 8-bit
media, in some instances your images may look better in 16 bit,
particularlywhen you use multiple filters or a complex filter with multiple
inputs.
Checkboxes
Display Project
Settings Window
When selected, this window is displayed each time that you launch FX.
Option Description