Adobe Extending Flash Professional CS5 - Manual (Page 63)

41 EXTENDING FLASH PROFESSIONAL
BitmapItem object
Last updated 5/2/2011
Description
Property; a Boolean value that specifies whether to use the default imported JPEG quality (
true ) or not ( false ).
Available only for JPEG compression.
Example
The following code sets the
useImportedJPEGQuality property of the first item in the library of the current
document to true :
fl.getDocumentDOM().library.items[0].useImportedJPEGQuality = true;
alert(fl.getDocumentDOM().library.items[0].useImportedJPEGQuality);