PRG Mbox Designer Manual 3.9 - Manual (Page 173)

MBOX ® MEDIA SERVER USER MANUAL 165
+ Use PMA: This setting is only used when converting Animation movies. If left unchecked, the application will not
pre-multiply each pixel’s color values by its alpha value. If checked, each pixel’s color will be pre-multiplied by its
alpha value.
+ Delete Gamma: This setting will cause the Gamma information saved with the file to be removed. In many cases,
this will result in a movie that does not have the same colors as the original, and should therefore be used with
caution.
+ Copy Audio. This setting will cause embedded audio to be retained (copied) when a file is converted. The default
action is to strip the audio.
Pre-Multiplying Alpha
When you "pre-multiply alpha," it multiplies the color (red, green, and blue) values for each pixel by that same pixel’s
alpha value. Each of these values range between 0.0 and 1.0 - 0.0 is none, 1.0 is full. Therefore, when using pre-
multiplied alpha, a pixel with an alpha value < 1.0 (i.e. it has some amount of transparency) will be rendered with the
intensity of its color values reduced. This is very useful for reducing the white or grey fringe seen around some objects
in content that uses an alpha channel.
The Mbox File Converter has one additional function: it can apply pre-multiplied alpha to a TIFF or PNG file that was
created using straight alpha. As noted above, this can help to reduce fringing around the edges of these files if they
were created improperly. When pre-multiplying alpha in still image files, there is no conversion of file-type or quality
adjustment.
File Conversion Procedure
Step 1. Locate MbE File Converter application in the MboxExtreme/Utilities folder. Double-click icon to open Mbox
File Convertor window... or, simply drag the movie file onto the Mbox File Convertor icon. If files are
"dropped" directly onto the application’s icon, then they will be processed with the most recently used
settings (if applicable).
Step 2. If the window is opened first, the settings can be adjusted. Adjust as required. Refer to "File Conversion
Settings" on the next page.
Step 3. Once the settings are adjusted, drag one or more movie files onto the application window.
Step 4. After conversion, manually remove the old files from the folder, so there are not two files with the same
index value.